Unit weight of steel bars – How to calculate?

Calculating the unit weight of steel bars with various diameters is crucial when creating a schedule for bar bending. The total weight of steel bars/TMT bars weight required for the project’s construction can be calculated once we know the unit weight of steel.

Steel is the most commonly used structural material. Steel’s basic components include metallic iron, non-metallic carbon, and minor amounts of nickel, silicon, manganese, chromium, and copper, among others. High tensile strength makes it a popular construction material for civil engineering projects. Steel reinforcement bars, often known as rebar, are placed in concrete members to enhance their tensile strength. As we all know, steel is utilised to construct structural members such as columns, beamsfootingsfoundations, and building slabs. Steel bars of various sizes are supplied by the manufacturer, with lengths of 12 metres or 40 feet.

  1. Why Unit Weight of steel bars Calculation is Important?
  2. How to calculate the steel bar weight/ TMT bars weight?
  3. Calculation of weight of steel bars per Running Meter
    1. Weight of steel per Meter
    2. Weight of steel per foot
    3. Weight of steel bars/TMT bars weight per meter

Why Unit Weight of steel bars Calculation is Important?

It is essential to comprehend the weight of steel bars since we estimate them as 100 metres 20 mm bar, 100 feet 16mm bar, and so on (is the sign for diameter). Steel bar manufacturers, on the other hand, will not interpret this notation and will measure the steel bars in weight. So we have to order them in kilogrammes, quintals, or tonnes. This article will go through how to use the steel weight formula to determine the steel bar’s weight.

How to calculate the steel bar weight/ TMT bars weight?

Steel bar unit weight is the weight of steel per unit volume. Its SI unit is kg/m3. The unit weight of steel is typically measured as follows

  • Kilogrammes per cubic metre (7850 kg/m3),
  • Kilo Newton per cubic metre (78.5 kN/m3),
  • Grams per cubic centimetre (7.85 g/cm3).
Unit weight of steel
Unit weight of steel bars

Calculation of weight of steel bars per Running Meter

Let’s start with a 12 mm diameter.

The length of the rod L = 1 meter.

Steel has a density of 7850 kg/m3.

Let us see how the formula calculates the weight of steel bars.

Area of steel rod (Circular shape) = πror πD2/4

Hence the wt of steel bar formula

= Area of steel x Density of steel x Length of steel

Where

Area of steel = πD2/4

The density of steel = 7850 kg / m3

Length of steel = 1 mtr

Diameter of steel = D mm

Weight of steel per Meter

= πD2/4 x 7850 x 1m = 3.14 x (D2 / 4) x 7850 x 1m

In this equation,

the Diameter is in mm and the Density (Unit Weight) is in m3

Let us convert the Diameter in mm2 to m as below

1 mm = 1/1000 m , 1 mm2 = 1/(1000)2 mm2

= 3.14 x (D2 /4 ) X 1/(1000) 2 X 7850 X 1

Weight of steel bars formula= D2 x 6162.5 x 1/(1000)2

= D2 x 1/(0.006162)-1

= D2 / 162.28

For calculation purposes, we used to take D2/162

Weight of steel rod per Running meter = D2/162 where D is the diameter of steel rod in mm

For a 12 mm dia rod,

D = 12 mm

Weight per meter = 12 x 12 /162 = 0.889 kg per rmt or meter length or unit length

If you want to know the steel weight per foot. 1 metre = 3.281 ft. Just multiply the same.

Weight of steel per foot

1 metre = 3.281 ft. Just multiply the same.

= D2/162 x 3.281 = D2 / 533

Weight of steel bars/TMT bars weight per meter

Let us have an idea about the unit weight of common diameters of reinforcement steel used in civil engineering construction.

Weight of steel bars/TMT bars weight per meter

Difference between Built up Area, Carpet area, Plinth Area

You may run into terminology like “carpet area,” “built-up area,” and “super built-up area” if you’re considering purchasing a home. There are various types of areas in a building’s floor plan. Reading a floor plan is an important skill for a civil engineer to have. These are various methods of describing a property’s area. In this article, we will see about the different types of areas.

  1. Types of areas in Building Construction
    1. Real Estate Regulation and Development Act, 2016, (RERA)
    2. Plot area (Areas of building)
    3. Carpet area (Areas of building)
    4. Plinth area
    5. Super built-up area
    6. Set back area

Types of areas in Building Construction

We should be informed with the following building construction practises before making home buying plans. Following are the terminologies usually followed in dealing with building construction.

  • Plot area
  • Built-up area or Plinth area
  • Carpet area
  • Setback area
  • Super built-up area

Before getting into these terms first we have to know what is RERA 

Real Estate Regulation and Development Act, 2016, (RERA)

The Real Estate Regulation and Development Act, 2016, (RERA) is an act established by the Indian parliament. The main objective of RERA is to give prompt information between the buyers and sellers. This increases transparency and reduces the chance of cheating.

There are three different ways to calculate the area of the property. 

  • In terms of the Carpet area
  • In terms of Built-up area
  • In terms of Super built-up area

While buying a property buyer should pay for the area which is usable. RERA provides safety of money, buyer protection and balanced agreement.

Areas of Building
Areas of Building

Plot area (Areas of building)

The plot area includes the complete area which you own. This area comes under the fencing.

Plot area
Plot area

Carpet area (Areas of building)

Carpet area is a term which the real estate agent uses the most. It is the area of the building which can be covered by using carpet. It is also called a net usable floor area. 

Carpet Area = Total floor area – Area of internal/external walls

But as per RERA Carpet area = Total Floor area – Area of external walls

According to RERA flats should be sold on the basis of carpet area. The carpet area as per RERA is the area of usable spaces such as bedrooms, kitchen, bathroom, toilet etc. It also includes an area covered by internal partition walls. It excludes areas such as Balcony, utility areas, external walls area, open terrace area, lift, lobby, staircase etc. Mostly carpet area is 70% of its built-up area. 

Carpet area
Carpet area

Plinth area

The plinth area is also known as the Built-up area. It is the total area of the building within the plot area. It is mostly 30% of the total plot area. 

Built-up Area = carpet area + Area of walls

It includes living room, bedrooms, utility, bathroom, wall thickness, kitchen, balcony closed staircases etc. and excludes open terrace area, lift, open staircase, swimming pool etc. It is 10 to 15 % more than the carpet area.

Plinth area
Plinth area

Super built-up area

Super built-up area was used to measure the area of property before the RERA act came into existence. Because the super built-up area lowers the rate per square foot. Saleable area is another name of super built-up area.

Super Built-Up Area = Setback area+Built-up Area+20% of common area 

Super built-up area includes common areas like swimming pool, clubhouses, lobby, staircase, Lift, etc. and the built-up area of the flat. 

Set back area

Set back area is the space between the boundary and the building. It is the minimum open space necessary around the building. As per the municipal regulation a specific margin should be provided between building and road. 

Setback area = Built-up Area – Plot area

Setback area
Setback area

This provides sufficient ventilation, ease in vehicle movement and protection from other entities

Types of doors – Top 7 door types explained

Types of doors commonly used in residential, commercial, and industrial construction depend on the application area, durability required, the purpose of the door, etc.

What is a door?

A door is a movable barrier or mechanism for opening and closing an entranceway or a building/room. The purpose of the door in this urban environment is security and privacy. Apart from security, safety, and privacy, an aspect of art, beauty, and elegance is associated with it. The entrance door acts as a warm welcome to the areas inside.

This article is about the types of doors popularly used in civil construction.

  1. Classification of doors in Civil Engineering
    1. Types of doors in civil engineering– location based
      1. Exterior door
      2. Interior door
    2. Types of Doors – Based on Materials
      1. Wooden Door/Timber Door
        1. Demerits of wooden doors
      2. Glass Doors
      3. Metal Doors
      4. Types of Doors – Flush Doors
      5. PVC Doors
      6. Types of Doors – UPVC Doors
      7. Types of Door – Aluminium doors
  2. Conclusion

Classification of doors in Civil Engineering

Doors come in a number of types. The selection of a door type, on the other hand, is determined by the location, purpose, aesthetic needs, material availability, security, and privacy. Doors types are typically classified as follows.

  • Location based
  • Based on material
  • Based on operation mechanism

Types of doors in civil engineering– location based

The doors types are classified as follows

  • Exterior Doors
  • Interior Doors

Exterior door

An outside door is one that allows entry to a building/house. An outside door’s main function is to safeguard the building as well as the security and privacy of the occupants of the building. While selecting an exterior door, style, colours, finishes, and aesthetic looks to match the architectural theme must be considered.

Interior door

Interior doors provide access to interior spaces like bed, kitchen, special functional rooms, toilets, etc. However, choice of material and type depends on the nature of privacy, security, and purpose of the room. Interior doors used to be lighter than exterior doors.

Types of Doors – Based on Materials

The door choice is confirmed based on the material to be used. For that, we should have a better idea of the readily available, durable, and aesthetically matching materials. Following are the popular choices of doors based on materials used in construction nowadays.

  • Wooden Doors
  • Glass Door
  • Metal Door
  • Flush Door
  • PVC door
  • Aluminium Door
  • UPVC door

Wooden Door/Timber Door

Wooden doors types are the most common and premium choice for both external and internal doors. They are the preferred choice due to their classy and elegant looks, high durability, and ability to match any architecture theme. Moreover, they are aesthetically pleasing and are widely available on a reasonable budget. Wooden doors can be custom-made for any functional requirements and design. They are the oldest material used and never lose their sheen even after long years.

wooden door
wooden door
  • Easily available
  • Easy working
  • Best material for front doors due to its high durability.
  • Used for any functional requirement.
  • Wooden doors are mostly polished rather than painted for exposing the natural grain looks.
  • Simple and easy installation.
  • Carving works are easily done on wooden doors.
  • Wooden doors are soundproof, got high thermal insulation capabilities and are strong.
Demerits of wooden doors

Even though wooden doors are superior materials they have their demerits also. However, needs periodic maintenance to retain the sheen and looks.

  • Needs periodic maintenance to retain the sheen and looks.
  • Wooden doors on long exposure to moisture may deteriorate.
  • Prone to termite attacks.
  • May sags

Glass Doors

Glass doors are for areas where the availability of natural light and open feeling is the main functional requirement. They are mainly used in areas where privacy is not a prime factor-like back yard, balcony doors, cabin doors, etc.

Glass doors are elegant and give an enhanced look to the house. However, the main problem with glass doors is the safety and privacy factor and the possibility of glass breaking. The glass breaking problem is managed by using small glass pieces for front doors. The glass should be safety glass or toughened glass.

Metal Doors

Steel is one of the preferred and favorite alternatives to wood for both external and internal doors. Mild steel or Galvanized steel is used for the manufacturing of doors. These doors are manufactured in solid and hollow types and are a safer, durable, and stronger option when compared to wooden doors.

metal door
metal door

Steel door frames are usually combined with wooden, PVC, steel, and flush door shutters. Steel door frames are manufactured by pressing steel sheets, angles, channels, etc. Holdfasts and hinges are welded to the steel frames.
Steel frames are popular and are used for residences, factories, industrial buildings, etc. They are economical than conventional wooden frames.

Metal door shutters are manufactured from high-quality cold-rolled Mild Steel (MS) sheets, with a steel face and rock wool or foam insulation. Steel is a more economical and stronger option compared to other materials even though steel may not look as attractive as wooden or glass doors.
Metal doors are available in different tones and shades. They are durable, have minimal maintenance, and provide excellent security.

Types of Doors – Flush Doors

The flush door is made of a timber frame covered with plywood from both sides. However, the hollow core is filled with rectangular blocks of softwood just like block boards. Flush door surface finished with decorative finish by fixing veneers. The flush door is usually laminated or veneered to match the architectural themes. These doors are usually hinged type and have one side opening only. The frame can be of wooden, PVC, or steel.
Flush doors got a seamless look and are economical, look elegant, and are easily available in the market.

flush door
flush door

While providing these doors for toilets, baths; the inner face of the door should be covered with aluminum sheets to protect against water.

PVC Doors

PVC or polyvinyl chloride doors are a very popular choice for doors. They are available in a range of colors and styles. Furthermore these doors have high resilience, are anti-destructive, termite-proof, moisture-resistant, lightweight, etc. As a result they are best suited for areas with moisture chances like bathroom areas.
Polyvinyl doors come in a variety of designs types. colors, style and looks beautiful. Similarly these doors do not corrode like steel or disintegrate like wood and do not need much maintenance.
They are very simple and easy to install and are scratch-proof. These doors are not preferred for front doors due to their lightweight characters and inability to resist environmental conditions. These doors are cost-effective when compared to wooden and metal doors.

Types of Doors – UPVC Doors

uPVC stands for Unplasticised Polyvinyl Chloride. It is a form of plastic that is hard and inflexible, also known as rigid PVC. UPVC doors are a preferred choice of architects and home owners due to the superior qualities they offer when compared to other door materials like wood, metal , PVC etc

  • Easy to clean and maintain – UPVC doors can be cleaned by simply wiping with a soft cloth soaked with mild detergents even though they may not peel or cracks after years of usage.
  • UPVC Profiles are manufactured to accommodate double glass units (DGU) in fact provides excellent thermal and acoustic insulations. Furthermore glass panes can be substituted with reflective glass to reflect sunlight and keep the rooms cooler in summers.
  • Durability – UPVC is a highly durable material, in addition to that allows for the construction of doors and windows that are long-lasting. In addition to all above they are dust-proof, termite-proof, moisture, and weather-resistant.
  • Ease of installation – Similarly UPVC doors are very fast and easy to install.
UPVC doors
UPVC doors

Types of Door – Aluminium doors

Aluminium doors due to their excellent and durable qualities are the most preferred option for designers and architects. They are durable, strong and maintenance free material. The fabrication and installation is very easy and got the choice of using as member for DGU units for thermal insulation applications. Aluminium is expensive, however considering the superior qualities aluminium is preferred in most of the areas.

Conclusion

Apart from the types described above there are a lot of doors varieties available in the market to cater each and every situation and applications. However, these door type selection has to be in line with the requirements.

Ultrasonic pulse velocity test || UPV Test – Types and Methodology

The ultrasonic pulse velocity test, or UPV test, is an example of a non-destructive concrete test. Generally, hardened concrete is subjected to non-destructive testing (NDT) and destructive tests (DT). Concrete is the world’s oldest and most significant construction material. Therefore, concrete testing is crucial for assessing the stability, strength, durability, and condition of structures.

Non-destructive testing of concrete is a way of analysing concrete structures without causing damage. This aids in ensuring the structural quality and condition. The strength of the concrete is also influenced by various characteristics, including hardness, density, curing circumstances, ingredient quality, workability and water-to-cement ratio, etc.

This article discusses the UPV test, which is one of the most well-liked and reliable non-destructive tests carried out on concrete structures.

  1. Ultra sonic Pulse Velocity test (UPV Test)
  2. Relevant IS code for Ultrasonic Pulse Velocity Test (UPV Test)
  3. Ultrasonic Pulse Velocity tester
  4. Principles of Ultrasonic Pulse Velocity test
  5. Objective of UPV tests
  6. Factors affecting Ultrasonic pulse velocity test
  7. Methodology of Ultrasonic Pulse velocity tests
    1. Direct method
    2. Indirect method
  8. Result interpretation of UPV testing
  9. Conclusion

Also read : Bitumen tests – 9 tests for flexible pavements

Ultra sonic Pulse Velocity test (UPV Test)

The most efficient and fast method of testing concrete is through ultrasonic pulse velocity tests, or UPV tests. The quality of concrete is assessed using the results of UPV tests, which evaluate the period of travel of ultrasonic pulse waves. A 50–55 kHz range must be maintained for the ultrasonic pulse wave’s frequency. The pulses are generated by the UPV tester’s pulse generator and are allowed to travel through the concrete. By monitoring the traversing distance and the duration, the pulse velocity can be determined. Higher velocity indicates that the density and elastic modulus of the concrete are higher.

Cracks and defects in the structure are detected using UPV tests. Significant variations in pulse velocity values are indicative of broken and degraded concrete. The concrete’s density and wave velocity are related. Therefore, this test has a tremendous potential for evaluating the quality of concrete.

Relevant IS code for Ultrasonic Pulse Velocity Test (UPV Test)

IS-13311 (Part 1):1992 (Reaffirmed- May 2013) “Non-Destructive Testing of Concrete- Methods of Test (Ultrasonic Pulse Velocity)”

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Ultrasonic Pulse Velocity tester

The UPV tester is the name of the type of equipment used to measure ultrasonic pulse velocity. The following accessories are included in ultrasonic pulse velocity tester.

  • Electrical Pulse generator
  • Pair of Transducers (probes)
  • Amplifier
  • Electronic timing device
Ultrasonic Pulse Velocity Tester
Ultrasonic Pulse Velocity Tester

Principles of Ultrasonic Pulse Velocity test

The electrical pulse generator generates pulses that are sent through the UPV tester’s transducer. Through the concrete surfaces, the pulse generates many reflections. Using the formula shown below, the pulse velocity is calculated.

Pulse velocity, V = L/T

where L is the traverse distance, T is the time for the receiver to receive the pulse

The geometry of the material is unrelated to the UPV test. Better concrete strength is associated with higher velocity and vice versa. One of the dynamic tests for concrete is the ultrasonic pulse velocity test.

Objective of UPV tests

The main objectives of the ultrasonic pulse velocity test or UPV tests are

  • To learn the homogeneity of the concrete.
  • Determines the presence of cracks, voids and imperfections. 
  • To calculate the elastic modulus of concrete. 
  • Finds the quality of concrete relative to the standard requirements. 
  • To determine the age of concrete. 

Factors affecting Ultrasonic pulse velocity test

The UPV test detects cracks and assists in structure development. However, a number of factors influence how pulse velocity is measured. As a result, compressive strength cannot generally be approximated from the pulse velocity. The following are the elements that impact the UPV test.

  • Presence of reinforcement
  • Water content
  • Mix proportion
  • Temperature of concrete
  • Concrete age
  • Stress level of concrete

Methodology of Ultrasonic Pulse velocity tests

Piezoelectric and magneto strictive types of transducers are suitable for use with the UPV test. Additionally, its frequency range should be between 20 and 150 kHz. The electronic timing device monitors time with an accuracy of 0.1 microseconds.

The transducer transmits the waves that travel through the concrete surface. The receiver transducer detects the electric signals that are generated once the pulse waves are transformed to them. The traversal length will be displayed as ( L). The electronic timing device calculates how long it takes for signals to arrive. Time is shown as (T).


The Electronic timing device measures the receiving time of the signals. The time is denoted as (T).

Pulse velocity (v) = L/T

There are three common methods for doing UPV tests. They are direct method and indirect method.

  • Direct Method of UPV Testing
  • Indirect Method of UPV Testing
Methodology of UPV test
Methodology of UPV test

Direct method

The maximum energy is transmitted at right angles to the face of the transmitter. As a result, to achieve the greatest results, the receiving transducer must be placed on the side of the transmitting transducer. This is referred to as the direct approach or cross probing.

Ultrasonic pulse velocity test
Ultrasonic Pulse velocity test -Types

Indirect method

In some circumstances, the opposite side of the structure may be inaccessible. The receiving and transmitting transducers are installed on the same face of the concrete members in this scenario. This is known as the indirect method or surface probing. This approach is less effective than the direct approach. The test findings are mostly influenced by the surface concrete, which has different properties from the structural components’ core concrete.

Result interpretation of UPV testing

The density and elastic modulus of concrete are correlated with the ultrasonic pulse velocity. This in turn depends on the components, mixing processes, placement techniques, concrete compaction and curing, casting temperature, etc.

The main causes of internal cracks and pockets in concrete are lack of compaction and concrete segregation. Lower pulse velocity values are a result of these concrete defects. However, the laboratory tests might have confirmed a well-designed concrete.

The range of pulse velocity in the direct method is as shown below.

  1. Above 4.5 Excellent
  2. 3.5 to 4.5 Good
  3. 3.0 to 3.5 Medium
  4. Below 3.0 Doubtful

Conclusion

The final assessment of compressive strength from UPV is not the sole criterion used to determine concrete strength. The strength is confirmed by comparing it to a compressive strength estimate derived from the same ingredient mix and conditions. The results of the UPV test and site tests conducted using similar ingredients may be correlated. When compared to actual UPV intensities, the numbers may change by about 20%.

Bitumen types for road Layers – Bitumen Emulsion types

Bitumen types for road layers are a vital topic to comprehend when it comes to road construction. Bitumen is preferred for flexible pavements in road construction because it has many advantages over other pavement construction materials. This article will demonstrate the importance of bitumen in road construction and the types of bitumen for road construction. Furthermore, bitumen emulsion types for road layers, different bituminous materials, cutback bitumen, bitumen grade, and bitumen attributes will be highlighted in this article.

  1. Bitumen types for Road layers /Flexible pavements 
    1. Tack Coat – Bitumen types for road layers
    2. Binder Course – Bitumen types for road layers
    3. Prime Coat – Bitumen types for road layers
    4. Base Course
    5. Sub Base Course
    6. Sub Grade
  2. Protective Asphalt
    1. Seal coat
    2. Slurry Seal
    3. Chip Seal
    4. Micro Surfacing
    5. Fog Seal

Bitumen types for Road layers /Flexible pavements 

The   flexible  pavement  structure   consists  of  the  following  layers: 

  • Tack   Coat  
  • Binder   Course 
  • Prime  Coat  
  • Base   Course  
  • Subbase Course
  • Subgrade Course
Bitumen types for road layers

Keep in mind that the primary component of the road is not protective asphalt. Protective asphalt is deployed to safeguard the road’s surface. Every layer mentioned above uses a different type of bitumen. We will illustrate what types of bitumen are used in each of these layers.

Tack Coat – Bitumen types for road layers

The application of coatings is a critical phase in the construction of asphalt roadways. Generally, a tack coat is a thin layer of asphalt emulsion or liquid bitumen used in between layers of hot mix asphalt to prevent slippage. Mostly, MC30 cutback bitumen, CRS-1, and CRS-2 emulsion bitumen are utilised in a tack coat layer of bitumen. The lower layer is sealed by the presence of a tack coat, which also increases the strength of both asphalt layers.

Bitumen types for road Layers

MC-30 is a medium-curing cutback bitumen that is ideal for cold climates. Basically, asphalt emulsions are the most often used tack coat materials. However, the most widely used slow-setting emulsions are SS-1, SS-1h, CSS-1, and CSS-1h (1). The usage of rapid-setting asphalt emulsions like RS-1, RS-2, CRS-1, and CRS-2 for tack coats is also on the rise.

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Binder Course – Bitumen types for road layers

The base course and the surface course are separated by the binder course. Generally, a binder course is used to keep the road surface from moving. Because the binder course is made out of coarse aggregates, less bitumen is utilised in the manufacture of this asphalt. In the hot asphalt of the binder course, various grades of pure bitumen can be utilised. The various grades of pure bitumen used in binder courses are listed in the table below.

Penetration Grade Viscosity Grade
30/40VG 10
40/50VG 20
60/70VG 30
80/100VG 40 
120/150
Bitumen types for road layers

Prime Coat – Bitumen types for road layers

A prime coat is a coating that is applied directly to the base layer. The primary objective of utilising the prime coat is to improve the bond between the base layer and the asphalt mix layer. It also fills in the voids. A priming coat might aid in sealing the base layer. The bitumen in prime coatings is either CSS or CMS.

Prime coats aid in reducing dust while protecting the granular base’s integrity throughout construction. In the event of a foundation that will be covered with a thin hot mix layer or a chip seal for a low-volume roadway, priming enables a good bond between the seal and the underlying surface, which might otherwise delaminate.

A primary coat is primarily responsible for safeguarding the substrate of a construction project before applying additional layers. They can also function as a binder with secondary and tertiary compounds in the preparation of asphalt, improving the adherence of the layers. Following the prime coat, a tack coat is applied to provide an adhesive bond between the tack coat and the subsequent layer of coating. For asphalt prime coat systems, the tack coat is one of the most vital parts of the process, as it connects the subsequent layers and forms the base of those layers’ strength.

Base Course

The base course is placed directly on top of the subbase course. This layer has a higher permeability than the sub-base layer because it is composed primarily of coarse aggregates. Basically, the base course, which is the first layer in direct contact with traffic, moves the weights from the upper layers to the sub-base course. Different base courses used in pavement include sand or stone base, macadam base, and bitumen base.

road-layers-of-flexible-pavement
road-layers-of-flexible-pavement

Sub Base Course

The first layer of flexible pavement constructed on the ground is the sub-base course. This layer is typically composed of river sand, an alluvial cone, and broken rock. Bitumen and cement can be used to stabilise the sub-base soil.

Sub Grade

It is the surface upon which further pavement layers such as the sub-base course, base course, and asphalt layers are placed. The subgrade absorbs any load tension or weight that is transferred from the top levels. A good subgrade should be able to support weights for a considerable amount of time without deforming.

Protective Asphalt

Generally, Protective asphalts are used to seal the road surface and improve the asphalt temporarily. However, It should be noted that asphalt sealing can cause the asphalt to become more slippery. Pure bitumen with low humidity and soluble bitumen are both utilised in protective asphalt. Because of its quickness and ease of installation, protective asphalt is more cost-effective than hot asphalt. There are various varieties of protective asphalts, some of which are listed below:

  • Seal coat
  • Slurry seal
  • Chip seal
  • Micro-surfacing
  • Fog seal

Seal coat

A seal coat is used to provide a long-lasting surface texture and to keep the surface waterproof. However, this kind of protective asphalt can be made using a variety of emulsion bitumen types, including CSS-1, SS-1h, SS-l, and CSS-1h.

Bitumen types for road layers

Slurry Seal

Generally, a slurry seal is used to lessen the harm done by bitumen oxidation. In the slurry seal, emulsion bitumens SS-1, SS-h1, CSS-1h, and CQS-1h are used. A slurry seal is appropriate for pavements with little to moderate damage, such as narrow cracks. However, it is not appropriate for severe damage such as holes.

Chip Seal

A chip seal is a thin protective surface that is applied to a pavement or subgrade. Water cannot easily seep through the base layer due to the chip seal. This layer also prevents freezing in areas where the temperature is below zero. Adding this layer improves the road’s reflectiveness for nighttime driving. A rapid-setting emulsion containing a CRS-2, RS-2, HFRS-2, and PMB is the best type of bitumen for chip sealing.

Micro Surfacing

Micro-surfacing aids in the sealing of cracks and the protection of existing bituminous layers against surface voids and minor ruts. Among the benefits of adopting this layer are environmental compatibility, cost-effectiveness, and fast construction time. PMB bitumens such as PMCQS-1h, PMQS-1h, and CQS-1P are suited for it.

Fog Seal

A fog seal is intended to neutralise the oxidation process that occurs over time. This layer protects the pavement surface by leaving a hard layer. This layer employs emulsion bitumen such as SS-1, SS-1h, CSS-1, or CSS-1h.

Bitumen for roads – Bitumen Uses, Grades and Types

Bitumen for roads is an important topic to understand when it comes to road construction. Bitumen is used in road construction because of the wide range of features and advantages it possesses over other pavement construction materials. The significance of bitumen in the construction of roads will be demonstrated in this article. In addition, we shall see bitumen road layers, various bituminous materials, cutback bitumen, bitumen grade, and bitumen properties.

  1. Bitumen for roads – Bituminous binder types
    1. Bitumen vs Tar – Comparison
    2. Tar manufacturing
  2. Desirable properties of bitumen- an important topic in bitumen for roads
  3. Bitumen for roads – Types of Bituminous materials
    1. Cutback bitumen
    2. Bituminous emulsion
  4. Grade of bitumen for roads – Types and Uses
  5. Bitumen road layers

Bitumen for roads – Bituminous binder types

There are two types of bituminous binder for road construction.

  • Bitumen (by distillation of crude oil)
  • Tar (Produced from coal)

So, what are the difference between them?

Bitumen vs Tar – Comparison

The table below shows a comparison between tar and bitumen.

BitumenTar
Petrolium productDistillation of coal or wood
Soluble in carbon disulphide and carbon tetrachlorideSoluble in toluene only
Temperature succeptibility is lowTemperature succeptibility is higher than bitumen
Free carbon content is lessFree carbon content is more
Comparison between tar and bitumen

Now, let’s sneak into the manufacturing of tar, being one of the important bituminous materials

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Tar manufacturing

Bitumen for roads - Construction in progress
Bitumen for roads – Construction in progress

Generally, tar is made by heating coal inside a chemical apparatus. Most tar is produced from coal as a byproduct of coke production, but it can also be produced from petroleum, peat or wood.

The major steps in tar manufacturing are,

  • Coal undergoes carbonation and produces crude tar
  • Crude tar undergoes distillation/ refining and produces a residue
  • The residue blends with distilled oil fraction and produces tar

I am going to tell more about the properties of bitumen now.

Also read: Classification of roads-5 types of roads full details

Desirable properties of bitumen- an important topic in bitumen for roads

Bitumen for roads - Properties
Bitumen for roads – Properties

The desirable properties of bitumen are,

  1. Viscosity of bitumen during mixing and compaction is adequate
  2. Bituminous material should not highly temperature and susceptible
  3. In presence of water the bitumen should not strip off from aggregate
  4. The adhesive property of bitumen binds together all the components without bringing about any positive or negative changes in their properties
  5. Bitumen is insoluble in water and can serve as an effective sealant
  6. Due to versatility property of Bitumen it is relatively easy to use it in many applications because of its thermoplastic property
  7. Bitumen play a vital role in distributing the traffic loads on the pavement to the layers beneath

Bitumen for roads – Types of Bituminous materials

Okay. So, what are the types of bituminous materials that are used in flexible pavement construction? Below is the list for you.

  1. Paving grade material
  2. Modified bituminous binder
  3. Cutback bitumen
  4. Bitumen emulsion

Among the list, cutback bitumen is the major. Let me tell you more details about cutback bitumen.

Cutback bitumen

Cutback bitumen is the bitumen the viscosity of which is reduced by a volatile diluent. It is used in low-temperature mixing.

Three types of cutback bitumen are available

  1. Rapid curing
  2. Medium curing
  3. Slow curing

The diluent while mixing varies with the type of cutback bitumen.

Type of cutback bitumenDiluent
Rapid curingNafthal, gasoline
Medium curingCarosine or diesel oil
Slow curingHigh boiling point gas oil
Type of cutback bitumen and suitable diluent

Bituminous emulsion

bitumen emulsion
Bitumen emulsion

A bitumen emulsion is a liquid product in which a substantial amount of bitumen suspended in a  finely divided condition in an aqueous medium and stabilized by means of one or more suitable material

Three types of bitumen emulsions are available

  1. Rapid setting
  2. Medium setting
  3. Slow setting

Also read: Alignment of road: Factors affecting- obligatory points with figures

Grade of bitumen for roads – Types and Uses

To determine the grade of bitumen, penetration test is conducted. The results are expressed in 1/10 mm. When penetration value is represented as 80/1000, it is called grading of bitumen.

The old method of grading is viscosity test. Two viscosities kinematic and absolute and penetration value by penetration test results are collected. Based on this, bitumen is graded. The tables shows the grade of bitumen and values of viscosity in accordance with penetration.

Grade of bitumenAbsolute viscosityKinematic viscosityPenetration
VG 1080025080- 100
VG 20100030060- 80
VG 30240035050- 70
VG 40320040040- 60
Grade of bitumen and viscosity

Let me tell you the application of each of the grade of bitumen now.

VG- 10- Used in spray application since viscosity is very less

VG- 20- Used in cold area

VG- 30- Commonly used in India

VG- 40- High grade bitumen used in high traffic areas

Okay. So, lets’ learn about the bituminous layers.

Bitumen road layers

Let’s first look into the road layers to understand bitumen road layers.

 bitumen road layers
bitumen road layers

The bitumen road layers come in the surface layer shown in the figure above. The figure below shows that. Bituminous mix consists of aggregate and binder. Aggregate consists of coarse aggregate, fine aggregate and filler less than 0.075mm.

Bitumen road layers
Bitumen road layers
  • Bituminous concrete consists of aggregate and bitumen.
  • Thickness of base course depends on grading of aggregate
  • Dense graded aggregates are provided in base course. That is the permeability will be very less
  • Number of voids should be very less
  • Dense bituminous macadam should be given as a binder course

So, the trip is over. Hope the time you spend for reading about the bitumen for road was worth it.

MUST READ: Road margins- 6 types of road margin in highway

Happy learning!

Aluminium Composite Panel || ACP sheets design

Aluminium composite panel, also known as an ACP sheet, is a modern panelling material used for building exteriors (facades), interiors, kitchen cabinets, and signage applications.

Aluminium composite panels are flat panels having a non-aluminium core sandwiched between two thin coil-coated aluminium sheets. Aluminium Composite Panel is the most durable and flexible decorative surface material available, with enhanced performance attributes. This article discusses the production process, ACP sheet types, advantages, and applications.

  1. What is an Aluminium Composite panel or ACP sheets ?
  2. Types of Aluminium Composite Panels (ACP)
    1. Non fire rated Aluminium Composite Panel (ACP)
  3. Fire rated Aluminium Composite Panels
  4. Advantages of Aluminium Composite Panels
    1. Light weight
    2. Flexible
    3. Availability and colour choices
    4. Environmental friendly
    5. Dimensional stability
    6. Smooth and elegant
    7. Cost
    8. Weather resistant and Durable
  5. Applications of Aluminium Composite Panels
    1. External and internal architectural cladding/partitions
    2. Internal partitions
    3. Signage
    4. Interior work
  6. Conclusion

What is an Aluminium Composite panel or ACP sheets ?

Aluminum composite panels are made up of two thin layers of aluminium sheets sandwiched by a polymer core. ACP sheet’s polymer core is made of Low-Density Polyethylene (LDPE) or Polyurethane. These polymer cores are made of components that are flammable and not fire-resistant. Because aluminium has a low melting point, the Aluminium composite panel is more flammable when the combustible polymer core is present. The presence of a combustible polymer core limits the use of Aluminium composite panel in fire-prone areas.

To improve fire resistance, polymer cores should be specially treated or over 90% (Non-Combustible Mineral Fiber FR core) sandwiched between two layers of aluminium skins should be used. To preserve the ACP sheets, polyvinylidene fluoride (PVDF), fluoropolymer resin (FEVE), polyester coating, and other materials are applied. The typical thicknesses of aluminium composite panel are 2 mm, 3 mm, 4 mm, and 6 mm.

Aluminium Composite Panels
Aluminium Composite Panels – Façade

Types of Aluminium Composite Panels (ACP)

Depending on the usage and fire rating standards ACP sheets are classified into two categories

  • Non fire rated grade
  • Fire rated grade

Non fire rated Aluminium Composite Panel (ACP)

Two thin layers of aluminium sheets plus a sandwiched polymer core make up aluminium composite panels. Aluminium Composite Panel’s polymer core is made of polyurethane or low-density polyethylene (LDPE). These Aluminium Composite Panels are not fire-rated since they are flammable and could catch fire. The use of these sheets is restricted based on the fire rating. The image below depicts a typical cross-section of an ACP sheet that is not fire-rated.

Non Fire rated or Standard Aluminium Composite Panel - Typical section
Non Fire rated or Standard Aluminium Composite Panel – Typical section

Fire rated Aluminium Composite Panels

Depending on the core composition, fire-rated Aluminium Composite panel can withstand fire for up to 2 hours. The core materials are the fundamental distinction between ACP sheets that are fire-rated and those that are standard. While the fire-rated ACP has a specially formulated fire-resistant mineral core, the standard ACP uses LDPE/HDPE as its core material. Fire resistant mineral core uses Magnesium hydroxide as core for enhanced fire retardant qualities. As the name suggests, Fire Grade Aluminium Composite Panels have the unique capability to withstand extreme temperatures. The highest grade ACP is fire retardant ACP (A2 GRADE), which contains over 90% inorganic material content.

Aluminium Composite Panel - Fire retardant grade
Aluminium Composite Panel – Fire retardant grade (Credits – Alstrong )

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Advantages of Aluminium Composite Panels

Aluminium Composite Panels are widely used nowadays because of their countless unique properties. Let’s highlight a few of its unique features that set it apart from other panelling materials.

Light weight

When compared to other building materials like steel, Aluminium Composite Panel is lightweight. This significantly reduces the design loads on the structure with big spans and vast areas involved. Lifting and erecting ACP sheets is simple. This, in turn, minimises labour and construction costs while maintaining the schedule.

Flexible

The ACP sheet is flexible and very simple to use. The installation process is quick and simple, and the fixing framework construction is uncomplicated.

Availability and colour choices

This composite panel has exceptional flexibility because to the vast range of finishes it supports. Aluminium composite board can be textured, solid, mirror, or wood type to meet any architectural concept. The colour and feel of real stone and wood are effectively replicated on aluminium.

Environmental friendly

ACP is an environmentally friendly material that is composed of 85% recycled aluminium. ACP’s cover sheets and core material are both recyclable.

Dimensional stability

Aluminium composite panels got high dimensional stability and the material can remain stable for a long period without changing the dimensions.

Smooth and elegant

The exteriors of buildings can have a pleasant and attractive appearance because to the smooth, elegant ACP surface.

Cost

ACP sheet is the most economical panelling option when compared with other panelling materials. The cost depends on the core materials. The fire grade materials are costlier than standard non fire rated ACP.

Weather resistant and Durable

ACP panels are UV resistant and chemical resistant. They are unbreakable stain-resistant, weather-resistant, termite resistant, moisture resistant, and anti-fungal.

Applications of Aluminium Composite Panels

ACP sheet is mainly used for a wide range of applications due to its extraordinary qualities. Major uses of the ACP sheet are as follows.

  • External and internal architectural cladding 
  • Internal partition
  • False ceilings
  • Signage
  • Machine coverings
  • Container construction

External and internal architectural cladding/partitions

For exterior cladding/façade applications, ACP sheets are used, thanks to their versatile qualities like UV resistance, fire resistance, and durability. ACP sheets come in a wide range of colours to match any architectural style. ACP sheet is the material of choice for facades and partitions because of its lightweight characteristics, simple fixing procedures, and quick construction.

Internal partitions

Aluminium Composite Panels in combination with aluminium, UPVC etc are used for office cabins and internal partitions. Partitions can be done with minimal space wastage.

Signage

ACP is used to render a wide variety of flexible exterior signs, as signage and hoardings are being used for exterior applications and must survive changes in temperature or weather

Interior work

ACP sheets are used for interior applications such as wall coverings, false ceilings, cupboards, portable kitchen cabinets, tabletops, column covers, and more.

Conclusion

ACP sheets are Green and environmentally friendly, easy to clean, and can shorten the construction period. ACP panels are resistant to corrosion, prevents acid and alkali, and other types of corrosion. Due to these versatile properties, ACP sheets are one of the popular choices in the construction sector.

Formwork in construction – Top 5 Formwork types

Formwork in construction refers to a mould used to shape concrete into structural shapes (beams, columns, slabs, shells) for buildings and other structures. Concrete is one of the most popular building materials due to its exceptional properties and advantages. However, in order to create construction components, concrete must be poured into a specific mould. In order to achieve the desired shape precisely, concrete is occasionally poured into formwork, a type of temporary mould. Formwork types in construction can also be categorised based on the type of structural member they are used in, such as slab formwork for use in slabs, beam formwork for use in beams and columns, and so forth. The formwork and any accompanying falsework must be sturdy enough to support the weight of the wet concrete without experiencing significant distortion.

Timber formwork is the most prevalent type of formwork used for minor buildings. This article explores the various forms of formwork used in construction as well as their characteristics.

  1. Significance of formwork in construction
  2. Quality of good formwork in construction
    1. Easy removal
    2. Economy
    3. Rigidity and strength
    4. Less Leakage
    5. Supports
  3. De-shuttering Period as per IS 456 – 2000 for formwork in construction
  4. Advantages of formwork in construction
  5. Types of formwork in construction
    1. Timber formwork in construction
    2. Plywood formwork
    3. Metal formwork
      1. Advantages of metal/steel formwork
    4. Aluminium formwork
      1. Advantages of Aluminium Formwork:
      2. Disadvantages of Aluminium Formwork
    5. Plastic formwork

Significance of formwork in construction

Formwork is frequently used in a range of shapes and sizes in buildingroadsbridgestunnels, corridor linings, hydroelectric power dams, agriculture headwork, sewage pipeline works, and other applications based on our design materials in the form of PCC and RCC. Falsework is the term for the structures that are needed for formwork in order to prevent movement during construction procedures. Formwork in construction requires a qualified crew and appropriate supervision to ensure high quality. Poor accuracy and expertise during the creation of the formwork lead to subpar work, which wastes time and money.

Form work in construction
Formwork

25 to 30 per cent of the total price of concrete construction is made up of the cost of the formwork. For bridges, this cost proportion could be higher. However, depending on the complexity of the structure, this may exceed 60%.

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Quality of good formwork in construction

Although there are numerous formwork materials, the following are general performance characteristics to satisfy the objectives of concrete construction is as follows.

  • Easy removal
  • Economy
  • Rigidity and strength
  • Less leakage
  • Supports

Easy removal

The design of the formwork should be such that it may be quickly removed with minimal pounding, resulting in less damage to the concrete.

Economy

Formwork serves no purpose in ensuring the stability of completed concrete. So, keeping safety in mind, its cost might be reduced. The formwork should be constructed with reasonably priced, lightweight, readily available materials that are both recyclable and reusable.

Rigidity and strength

Good formwork should be capable to withstand any form of live or dead load. Formwork must be properly aligned to the target line, and levels must have a plane and solid surface. When exposed to weather, the formwork’s material shouldn’t swell or warp. When choosing the formwork, take into account the temperature of the pour as well as the type of concrete being used because both affect the pressure that is applied. Furthermore, the formwork must be sturdy enough to bear the weight of both wet and dry concrete.

Less Leakage

Joints must not leak at any point.

Supports

Formwork needs falsework, which consists of stabilisers and poles, in order to stop moving while construction is being done. Formwork needs to be supported by sturdy, rigid, and rigid supports.

De-shuttering Period as per IS 456 – 2000 for formwork in construction

Let us have a look into the de-shuttering period of various structural components as per IS 456-2000

Sr. No.Type of FormworkMinimum Period Before Striking Formwork
1.Vertical formwork to columns, walls, beams16-24 hours
2.Slab ( props left under )3 days
3.Beam soffits ( props left under )7 days
4.Props for Slab
(a).Spanning up to 4.5m7days
(b).Spanning over 4.5m14days
5.Props to Beam and Arches
(a).Spanning up to 6m14days
(b).Spanning over 6m21days

De-shuttering period as per IS 456

Advantages of formwork in construction

Formwork is unquestionably necessary for all construction projects; its fundamental benefit is that no other technique can take its place.

  • Concrete structures can be swiftly and affordably built by using formwork.
  • A formwork provides suitable access and working platforms throughout the whole construction process, thereby, enhancing worker scaffold safety.
  • Formwork helps to reduce project timelines and costs by shortening the floor-to-floor building cycle time, which implies that more projects can meet their budgetary requirements. This, in turn, enables construction managers to provide precise on-time shuttering and de-shuttering of formwork resources, which improves project effectiveness and resource utilisation.
  • Formwork assists in creating a smooth concrete finish surface.

Types of formwork in construction

The following are the major types of formworks commonly used in construction.

Timber formwork in construction

One of the first types of formwork utilised in the construction industry was timber formwork. Basically, timber formwork is the most versatile form, is built on-site, and has numerous advantages. In comparison to metallic formwork, they are incredibly lightweight and easy to install and remove. Timber formwork is versatile and can be built to any shape, size, or height. However, for minor projects where the use of local wood is permitted, these kinds of formworks are cost-effective. Prior to usage, the lumber must, however, undergo a thorough inspection to make sure it is termite-free. Timber formwork also has two disadvantages that should be considered: it has a short lifespan and takes a long time on large projects. Timber formwork is frequently recommended when labour costs are low or when flexible formwork is required for complex concrete components.

Timber formwork
Timber formwork in construction

The timber formwork should be well-seasoned, small in size, easy to nail without breaking, and free of slack knots. During shuttering, every face of timber that will make contact with the exposed concrete work must be even and smooth.

Plywood formwork

Generally, for plywood shuttering, sheets of waterproof, boiling-level plywood that are suited for shuttering are commonly used. These plywood sheets are attached to wooden frames to form the desired-size panels. Typically, plywood formwork is used in the sheathing, decking, and form-lining applications. Hence, Plywood formwork is the modern-day alternative to wooden formwork in construction. To support the concrete work, this formwork incorporates plywood. Plywood formwork results in a smooth concrete surface, which eliminates the need for concrete refinishing. Accordingly, with the use of large-size panels, a wider area can be covered. Basically, for jobs like fixing and disassembling, this might result in labour savings. The number of reuses is higher as compared to wooden shuttering. The number of reuses might be approximated to be between 10 and 15 times.

Plywood formwork
Plywood formwork in construction

Many of the same characteristics of timber formwork, such as strength, durability, and lightweight, also apply to plywood formwork. The ability of plywood shuttering to withstand moderate weather conditions is one of its key benefits. The surface of plywood seems to be sturdy, and it is robust enough to support the weight of concrete.

Metal formwork

Steel shuttering is composed of panels with thin steel plates that are connected at the edges by small steel angles. Suitable clamps or bolts and nuts can be used to secure the panel units together, Likewise, this type of formwork is used in the majority of bridge construction projects. Because of their long lifespan and adaptability, steel hardware and formwork are becoming more popular. Despite its potential cost, steel shuttering is beneficial for a wide range of applications and constructions. Basically, steel shuttering gives the concrete surface an extremely flat and smooth finish. It is ideally suited for circular or curved structures such as tanks, columns, chimneys, sewers, tunnels, and retaining walls.

Metal formwork
metal formwork

Advantages of metal/steel formwork

  • It gives the surface of the member a highly smooth and levelled finish.
  • Steel shuttering has a long lifespan and is effective and strong.
  • The honeycombing effect is reduced and it is waterproof.
  • It can be used more than 100 times.
  • The concrete surface does not collect moisture through the steel shuttering. Likewise, it is simple to assemble and de-shuttering.

Aluminium formwork

Aluminium shuttering resembles steel shuttering. The main difference is that aluminium has a lower density than steel, which makes formwork lighter. There are a few things to consider before using aluminium in a construction project. Compared to steel, aluminium is less strong. Aluminium shuttering is cost-efficient when deployed in several construction projects engineered for repeated use. The major disadvantage is that once the shuttering is constructed, it cannot be changed.

Aluminium shuttering

Advantages of Aluminium Formwork:

  • A smoother, cleaner surface finish is produced.
  • Generally, Up to 250 re-uses were intended for aluminium formwork.
  • It’s also cost-effective if numerous symmetrical structures need to be constructed.

Disadvantages of Aluminium Formwork

  • The initial cost is higher since aluminium formwork is now more expensive. Such formwork is cost-effective when used in symmetrical building designs.
  • Setting up initially takes some time.
  • Professional services are necessary in order to align and maintain this kind of formwork.
  • In order to prevent future leaks, the formwork holes made by wall ties should be correctly blocked.

Plastic formwork

Interlocking panels or modular systems, which are both light and strong, are used to construct plastic shutters. Generally, small, repeatable initiatives like low-cost housing complexes are where it works best.

Plastic formwork
Picture courtesy: Newstrail.com

Basically, plastic formwork is appropriate for plain concrete structures. Due to its lightweight and water-cleanability, plastic shuttering is ideal for large segments and multiple reuses. Its primary drawback is that it is less flexible than timber because many of its components are prefabricated. However, large housing projects and structures with similar shapes are increasingly using these shuttering techniques.

 

UltraTech Cement commissions 1.9 mtpa cement capacity in Pali – Rajasthan

On Tuesday, the Aditya Birla Group company announced that the 1.9 mtpa greenfield clinker-backed grinding capacity at Pali Cement Works in Rajasthan had been put into operation.

According to the corporation, this is a part of the first phase of capacity increase that was announced in December 2020.

With 5 different plant locations, the firm and its subsidiary can now produce 16.25 mtpa of cement in Rajasthan.

The total capacity of UltraTech Cement for the production of cement in India is currently 121.35 mtpa. Outside of China, UltraTech Cement is the third-largest cement manufacturer in the world, with a combined Grey Cement capacity of 121.25 MTPA.

Despite a rise in net sales of 15.78% to Rs 13,596, the cement manufacturer’s consolidated net profit fell 42.47% to Rs 756 crore.

Types of bonds in brick masonry walls – Advantages and features

Types of bonds in brick masonry commonly used in construction are detailed in this article. The process of bonding bricks with mortar in between them is known as brick masonry. Bricks are arranged in a pattern to maintain their aesthetic appearance and strength. This article is about the various types of bonds in brick masonry walls.

Bricks are rectangular construction materials. Bricks are commonly used in the construction of walls, paving, and other structures. They are also inexpensive and simple to work with.

  1. Types of Brick masonry bonds – Features
  2. Types of Bonds in brick masonry
    1. Stretcher bond – Types of Bonds in brick masonry
      1. Limitations of Stretcher bonds
      2. Applications of stretcher bonds
    2. Header bond – Type of Bonds in brick masonry
    3. English Bond – Types of bonds in brick masonry
    4. Flemish Bond
    5. Double flemish bond
    6. Single Flemish Bond
    7. Raking bond
    8. Zigzag Bond
    9. Facing Brick Bonds
    10. Dutch Bond
    11. Rat trap bond

Types of Brick masonry bonds – Features

For all types of brick masonry bonds to be stable and of high quality, the following characteristics must be followed.

  • Bricks should be uniform in size.
  • The lap should be a minimum of 1/4 brick along the length of the wall and 1/2 brick across the thickness of the wall.
  • Uniform lapping is to be maintained.
  • Avoid using too many brickbats.
  • For getting a uniform lap Length of the brick should be twice its width plus one joint.
  • The centre line of the header and stretcher in the alternate courses should coincide with each other for the stable wall.
  • Stretchers should be used in facing and a header should be used in hearing.

Types of Bonds in brick masonry

There are different types of brick masonry bonds. They are

  • Stretcher Bond
  • Header Bond
  • English Bond
  • Flemish Bond
  • Raking bond
  • Zigzag Bond
  • Herring-Bone Bond
  • Facing Bond
  • Dutch Bond
  • Diagonal Bond
  • Rattrap bond

Let us have a look at the most commonly used types of bonds in brick masonry.

Stretcher bond – Types of Bonds in brick masonry

The stretcher is the brick’s lengthwise face or otherwise known as the brick’s longer, narrower face, as shown in the elevation below. Bricks are laid so that only their stretchers are visible, and they overlap halfway with the courses of bricks above and below. Accordingly, In this type of brick bond, we lay the bricks parallel to the longitudinal direction of the wall. In other words, bricks are laid as stretchers in this manner. It is also referred to as a walking bond or a running bond. Additionally, it is among the simplest and easiest brick bonds.

Stretcher Bond - Types of bonds in brick masonry
Stretcher-Bond

Limitations of Stretcher bonds

  • Stretcher bonds with adjacent bricks, but they cannot be used to effectively bond with them in full-width thick brick walls.
  • They are only suitable for one-half brick-thick walls, such as the construction of a half-brick-thick partition wall.
  • Stretcher bond walls are not stable enough to stand alone over longer spans and heights.
  • Stretcher bonds require supporting structures such as brick masonry columns at regular intervals.

Applications of stretcher bonds

Stretcher bonds are commonly used as the outer facing in steel or reinforced concrete-framed structures. These are also used as the outer facing of cavity walls. Other common applications for such walls include boundary walls and garden walls

Header bond – Type of Bonds in brick masonry

Generally for header bond, the header is the brick’s widthwise face. In brick masonry, a header bond is a type of bond in which bricks are laid as headers on the faces. It’s also referred to as the Heading bond. The header is the brick’s shorter square face, measuring 9cm x 9cm. As a result, no skilled labour is required for the header bond’s construction. While stretcher bond is used for half brick thickness walls, header bond is used for full brick thickness walls that measure 18cm. Generally, in the case of header bonds, the overlap is kept equal to half the width of the brick. To achieve this, three-quarter brickbats are used in alternate courses as quoins.

header bond - Types of bonds in brick masonry
header bond

English Bond – Types of bonds in brick masonry

English bond uses alternative courses of stretcher and headers and is the most commonly used and the strongest bond in brick masonry. However, a quoin closer is used at the beginning and end of a wall after the first header to break the continuity of vertical joints. Mostly, a quoin close is a brick that has been cut lengthwise into two halves and is used at corners in brick walls. Similarly, each alternate header is centrally supported over a stretcher.

Types of bonds in brick masonry - English bond

Flemish Bond

In Flemish bond, each course is a combination of header and stretcher. Accordingly, the header is supported centrally over the stretcher below it. Generally,closers are placed in alternate courses next to the quoin header to break vertical joints in successive layers. Flemish bond, also known as Dutch bond, is made by laying alternate headers and stretchers in a single course. The thickness of Flemish bond is minimum one full brick.The drawback of using Flemish bond is that it requires more skill to properly lay because all vertical mortar joints must be aligned vertically for best results. Closers are placed in alternate courses next to the quoin header to break vertical joints in successive There are two types of Flemish bond

  • Double Flemish bond
  • Single Flemish bond

Double flemish bond

The double flemish bond has the same appearance on both the front and back faces. As a result, this feature gives a better appearance than the English bond for all wall thicknesses.

Single Flemish Bond

The English bond serves as the backing for a single flemish bond, which also includes a double flemish bond on its facing. As a result, both the English and Flemish bonds’ strengths are utilised by the bond. Similarly ,this bond can be used to build walls up to one and a half brick thick. Howerver,high-quality, expensive bricks are used for the double-flemish bond facing. Cheap bricks in turn may be used for backing and hearting.

The appearance of the Flemish bond is good compared to the English bond.  Hencer, flemish bond can be used for a more aesthetically pleasing appearance. However, If the walls must be plastered, English bond is the best choice.

Flemish bond

Raking bond

Raking bond is a type of brick bond in which the bricks are laid at angles. In this case, bricks are placed at an inclination to the direction of walls. Generally, it is commonly applicable for thick walls. Normally laid between two stretcher courses. There are two types of Raking bonds

raking bond
  • Diagonal bonds
  • Herringbone bonds

Diagonal bonds

In diagonal bonds, bricks are laid inclined, the angle of inclination should be in such a way that there is a minimum breaking of bricks. These dioganal bonds are mostly applicable for walls of two to four brick thickness. Similarly, the triangular-shaped bricks are used at the corners. 

Herringbone bonds

This type of bond is applicable in thick walls. The bricks are laid at an angle of 45 degrees from the centre in two directions. Mostly used in paving. 

Zigzag Bond

In this type of bond, bricks are laid in a zig-zag manner. It is similar to the herringbone bond. Since Zig zag bond has an aesthetic appearance it is used in ornamental panels in brick flooring. 

zig zag bond
zig zag bond

Facing Brick Bonds

In facing bond bricks are used of different thicknesses. It has an alternative course of stretcher and header. The load distribution is not uniform in this type of bonding. So it is not suitable for the construction of masonry walls.

facing bond
facing bond

Dutch Bond

It is a type of English bond. The specific pattern of laying bricks for building a wall is known as English and Dutch bonds. The primary distinction is that English Bond is a bond used in brickwork that consists of alternate courses of stretchers and headers. Dutch bond – made by alternating headers and stretchers in a single course.

Rat trap bond

rat trap bond
rat trap bond

Another name of the rat trap bond is the Chinese bond. In this type of bond, the bricks are placed in such a way that a void is formed between them. These voids act as thermal insulators. Thus provides good thermal efficiency. It also reduces the number of bricks and the amount of mortar. Construction of rat trap bonds requires skilled labours.

Concrete Mixing || Mixing concrete – Objectives and types

Concrete Mixing or Mixing of concrete is the complete blending of the ingredients necessary for the production of a homogeneous concrete. In the previous blogs, we saw different types of concrete and their quality tests. Today, let me walk you through the details of it.

To begin with, let’s try to understand the objectives of mixing concrete and concrete mixing types

  1. Objectives of Concrete Mixing
  2. Concrete Mixing Types
    1. Hand Mixing of concrete
      1. Process – Hand Mixing of concrete
    2. Machine Mixing of Concrete
      1. Concrete Mixing Machine
      2. Machine Mixing Process
    3. Ready Mix Concrete
    4. Mixing Ratios
  3. Conclusion

Objectives of Concrete Mixing

How many of you have wondered why we mix concrete? Read on to find the answers.

  • To manufacture high-quality fresh concrete, proper mixing of materials is critical. 
  • The surface of all aggregate particles is coated with cement paste during the mixing phase.
  • For the desired workability and performance of concrete in both the fresh and hardened states.
  • To avoid segregation and bleeding.

In the next section, we will learn the types of concrete mixing

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Concrete Mixing Types

There are three methods to produce efficient and high-quality concrete.

  • Hand Mixing – Mixing concrete manually without a mixer machine.
  • Machine Mixing – Mixing using a mixer machine.
  • Ready Mix Concrete – Mixing is done in an automatic or semi-automatic batch plant.

Let’s dig deeper into each of them.

Hand Mixing of concrete

  • Method of manually mixing the concrete materials without the use of a mixer machine. 
  • Hand mixing is done only for small jobs where the concrete demand is low and quality control is not critical. 
  • Uniformity of mixing is difficult to achieve by hand mixing. It necessitates extra caution and effort. 
  • In the case of hand mixing, 10% more cement should be applied to the nominal mix concrete proportion.
Hand mixing of concrete
Hand mixing of concrete

Process – Hand Mixing of concrete

  • Hand mixing is done on a flat iron sheet plate base that is hard, clean, and non-porous.
  • On the platform, a measured amount of sand is placed.
  • Then the cement is poured over the sand.
  • In a dry state, the sand and cement are thoroughly combined with shovels several times until the mixture achieves an even colour.
  • The coarse aggregates are then spread out on top of the above mixture and thoroughly mixed. 
  • The whole mixture is properly mixed by twisting it from centre to side, back to centre, and then to the sides several times.
  • After that, depression is rendered in the mixed materials’ nucleus.
  • 75 per cent of the necessary amount of water is then poured into the depression and mixed with shovels.
  • Finally, the remaining water is applied, and the mixing process is repeated until the concrete has a uniform colour and consistency. 

The total time for concrete mixing does not exceed 3 minutes.

Let’s move on to the next method ie mechanised concrete mixing.

Machine Mixing of Concrete

  • The method of combining concrete materials with a concrete mixer system is known as machine mixing. 
  • It meets the demands of fast mixing times, optimal consistency, and homogeneous concrete efficiency. 
  • Since it ensures uniform homogeneity, machine mixing of concrete is best suited for large projects requiring large quantities. 

Concrete Mixing Machine

It is also known as a concrete mixer is a machine that mixes cement, aggregate (such as sand or gravel), and water in a uniform manner to shape concrete. A rotating drum is used to combine the components in a traditional concrete mixer. Concrete mixers powered by gasoline, diesel, or electricity are now widely available. The mixer machine is mostly used for mixing ingredients by volume. They are also used for mixing ingredients by weight by providing weigh batcher.

Mixer machine in action
Mixer machine in action

Machine Mixing Process

  • Wet the inner surfaces of the concrete mixer drum first.
  • The coarse aggregates are added first, followed by sand, and finally cement, in the mixer.
  • In a mixing machine, combine the products in a dry state. In most cases, 1.5 to 3 minutes should suffice.
  • While the machine is running, slowly add the appropriate amount of water after the dry materials have been thoroughly mixed. 
  • Don’t use any extra water.
  • Concrete must be mixed in the drum for at least two minutes after adding water.

We have seen the details of machine mixing. How about getting an idea about ready-mix concrete?

Ready Mix Concrete

  • Ready Mix Concrete (RMC) is a specialised material in which the cement, aggregates, and other materials are weighed and batched at a central location, then mixed either in a central mixer or in truck mixers. Then it is shipped to construction sites.
  • The consistency of the resulting concrete is much superior to that of site-mixed concrete.
  • Useful on congested sites or in road construction where space for a mixing plant or aggregate storage is limited or nonexistent. 
  • Quality control of concrete is simple in this process.

So far, I have showed you the types of concrete mixing and its procedures. Now its time to throw some light on concrete mixing ratios.

Ready Mix concrete plant
Ready Mix concrete plant

Mixing Ratios

The proportions of concrete components such as cement, sand, aggregates, and water are known as concrete mix ratios. The method of building and mix designs are used to determine these ratios. In comparison to other mixing processes, the water/cement ratio in RMC can be easily managed.

Conclusion

To summarise,

  • Hand blending of concrete is the cheapest method.
  • It is only recommended for very limited projects requiring a small amount of concrete since consistent concrete consistency is difficult to achieve with this method. 
  • It ensures proper material mixing.
  • When compared to site mixing (both hand and machine mixing), RMC takes less time and produces a higher quality product.
  • It’s also very handy when you need a large amount of concrete per day.

Test of cement on site – Field tests of Cement

Test of cement on site or field tests of cement is one of the most crucial things to be performed to assure the quality of the construction. Every structure is made up of hundreds of different building materials, such as sand, cement, aggregates, bricks, tiles, marble, and so on. However, the quality of the building materials is crucial for producing a high-quality structure and should be regularly evaluated at various phases of construction. Cement is the most important material used in construction and is responsible for the overall strength of the structure. In order to guarantee excellence in building, cement quality must be properly.

This article is about the various test of cement on-site or field tests of cement to ensure quality.

  1. Test of cement on site – Significance
  2. How to check cement quality?
  3. Test of cement on site / Field tests of cement
    1. Checking the manufacturing date of cement
    2. Visual checking for Lumps for the test of cement on site.
    3. Feel test of cement on site
    4. Heat of cement
    5. Colour
    6. Water float test
    7. Setting test
    8. Conclusion

Test of cement on site – Significance

Cement plants are generally found in isolated areas near limestone mines. Generally, clinker is produced by cement companies at a centralised clinkerization plant. Clinkers are either ground at the clinkerization facility or transported to strategically placed grinding units for grinding and cement bag packing. The manufactured and packed cement is transported and delivered to the prescribed destinations by road or rail. Even with the finest protection, the cement still has the potential of absorbing moisture while being transported. After absorbing moisture, the cement tends to harden, deteriorating its quality. Because of these unforeseen concerns, cement must be tested for quality before being used in construction. Basically, cement testing is carried out in accredited laboratories.

How to check cement quality?

The characteristics of cement are often determined by laboratory tests. Lab tests need time, specialised equipment, and expertise to evaluate and interpret the data. All of the cement’s qualities might not be able to be tested on-site. To address this issue, cement tests are divided into two types.

  • Field Tests of Cement

This article is about the field tests of cement.

test of cement on site
FIELD TEST OF CEMENT

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Test of cement on site / Field tests of cement

Some simple field tests can be used to confirm the quality of cement. Generally, these tests do not require the use of costly equipment or professional skills, and the results are obtained quickly. We can determine whether to accept or reject the cement by doing these quick tests, analysing the findings, and drawing conclusions about its quality. These are preliminary evaluations, and the cement’s quality is confirmed by factors such as how smooth it feels to the touch and its colour etc.

  • Checking the manufacturing date of cement
  • Visual checking for lumps
  • Feel test of cement
  • The heat of cement test
  • Colour test of cement
  • Water float tests
  • Setting tests
Test of cement on site
Field tests of cement

Checking the manufacturing date of cement

When stored under perfect conditions, the cement must be utilised within 90 days of manufacture. The manufacturing date and batch number are imprinted on each cement bag. By verifying the manufacturing date, we can get a good indication of how old the cement is and decide whether to use it. In addition, every batch of cement is accompanied by a Manufacturers Test Certificate, which can be requested and examined to verify the dates of manufacture.

Visual checking for Lumps for the test of cement on site.

Cement can be inspected for visible lumps. To establish the potential existence of lumps, you can press the cement bag’s corners. This test determines if the cement has hardened or not.

Feel test of cement on site

Feel a pinch of cement between the figures. Cement has to feel smooth and not grainy. By this test, we can rule out the presence of any adulterated material like sand mixed with cement.

Heat of cement

Put your hand inside a bag of cement that is open. If the cement is of good quality and has not yet begun to hydrate, the hand feels cool.

Colour

Cement is usually greenish-grey in colour. We can verify and confirm the colour of the cement on-site. However, the type and source of the ingredients can affect the colour of the cement.

Water float test

This test is performed to find out whether there are impurities in cement. A cement hand is thrown into a bucket of water. The cement floats for a while before settling down if it is good cement free of impurities or other foreign objects. Impurities in the water can cause the cement to settle instantly.

Setting test

A thick paste of cement is applied to a glass piece and slowly immersed in water for 24 hours. The cement piece won’t break or alter shape while it sets and maintains its original shape. This cement is regarded as excellent.

Conclusion

We have the opportunity to contact cement manufacturers through their customer services if we have any questions about the product’s quality and they will be happy to help. It is possible to confirm field observations with laboratory tests. Cement quality should never be compromised during construction. Because the most crucial component that affects the durability and quality of a structure is cement.

ALSO READ : WHAT ARE THE PROPERTIES OF CEMENT?

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Cofferdams-Types of Cofferdam and construction

Cofferdams are enclosures built inside bodies of water such as lakes and rivers to provide a dry working environment throughout the construction period. Cofferdams are temporary dykes that are built across a body of water. They allow the water to be pumped outside, ensuring a clean and dry construction site.

This article is about the significance and definition of Cofferdam and about the different types of cofferdams preferred in construction works.

  1. Significance of cofferdams
  2. What is a Cofferdam?
  3. Types of cofferdams
    1. Earthen cofferdam
    2. Rock-fill cofferdams
    3. Single walled cofferdams
    4. Double walled cofferdams

Significance of cofferdams

Construction in water is the most challenging task in civil engineering. A safe and dry working environment is necessary to preserve the project’s safety and construction quality. However, various strategies are used to construct structures in the water and maintain the area’s dryness. One of the most popular and widely utilised ways is the use of cofferdam.

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What is a Cofferdam?

Making cofferdam involves building watertight barriers all around the construction site, pumping the water out to expose the water, and then erecting the cofferdams. For bridge piers, marine jetties, ports, etc. cofferdams are preferred. Size, water depth, water flow velocity, and other factors affect the design and types of cofferdam. Let us have a look into the types of cofferdams popularly used in construction.

Types of cofferdams

Depending on the design requirements, water depth, soil conditions, type of material used, etc., coffer dams are classified into many types.

  • Earth cofferdam
  • Rock fill cofferdam
  • Single sheet pile cofferdam
  • Double-wall sheet piling cofferdam
  • Braced cofferdam
  • Cellular cofferdam

Earthen cofferdam

Earthen cofferdam is the most common and simplest type of cofferdam. They are appropriate for locations with minimal water depth and water current. Sand, soil, clay, and boulders that are readily available locally are used to construct earthen cofferdam. The earthen cofferdam must be at least one metre above the maximum water level.

When an area of excavation is quite extensive, earthen cofferdam is used and require a sizable base area. To withstand water pressure and seepage, impervious clay core or sheet piles are driven in the centre. In order to prevent scouring and possible dam failures, the upstream side is stone-pitched. These technologies do not, however, completely provide waterproof zones. Generally, to remove the water, pumps and waterproofing systems must be installed.

Earthen Cofferdams
Earthen Cofferdams

Rock-fill cofferdams

When compared to earthen cofferdams, rockfill cofferdams are superior. The choice of rockfill dams is influenced by the cost and availability of rocks in the area. Generally, the rockfill dam’s maximum height should be limited to under 10 feet. The rockfill area is pervious and will be lined with an impervious clay layer to prevent seepage and dam failure.

Rock filled Cofferdams
Rock filled cofferdam

Single walled cofferdams

When the depth of the water is less than 6 metres and the area of work is localised, such as on a bridge pier, single-walled cofferdams are preferred. Basically, single-walled coffer dams are primarily built by driving steel sheets into the inside as a support layer after driving timber sheets into the exterior as guide piles. In situations where the water is deep, guide piles may be steel sections.

After the guide piles have been driven, wales or runners made of wood logs are bolted to the guide piles at appropriate vertical intervals. Wales are used to position the inside sheets’ distance from the wooden planks at a specific distance as shown in the figure. Mostly, these wales are fastened to the sheets using bolts from both sides.

Single walled Cofferdams
Single walled cofferdam

The inside sheet piles have strong bracing. Sandbags are positioned on both sides of the walls to increase stability even more. For clay, the penetration depth should be approximately 1 metre, 0.5-0.75 metres for sand, and 0.25-0.5 metres for gravel, etc. Construction can begin when the interior water has been pumped out.

Also Read : Reservoirs vs Dams – Reservoir – types and functions

Double walled cofferdams

Double-walled cofferdams are preferred when the construction area is large, the water depth is higher than 6 metres, and single-walled cofferdams appear to be uneconomical. Double-walled cofferdams Consist of two straight, parallel vertical walls of sheet piling coupled together, with the space between them filled with soil. If the height is greater than 3 mtr, double wall sheet piles must be strutted as illustrated in the figure.

Double walled cofferdams
Double walled cofferdams

In order to give stability to the cofferdam, the filling materials must be carefully chosen while taking the coefficient of friction into account. The sheet piles are driven into the bed in the upstream area to a good depth to avoid leaking from the ground below.

Waffle Slab or Ribbed slab details and Construction, Advantages

Waffle slabs are ribbed reinforced concrete slabs. A waffle slab often referred to as a ribbed slab, is a structural component that is plain on top and has a grid pattern on the bottom. A waffle slab also called a two-way joist slab got ribs running perpendicular to each other in two directions on the underside. This slab resembles pockets of waffles because of its grid pattern. Hence they are named Waffle slab systems.

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For spans longer than 40 feet (12 metres), waffle slabs are chosen because they are stronger than flat slabs, flat slabs with drop panels, two-way slabs, one-way slabs, and one-way joist slabs. These are more expensive than other slabs but in turn, are more rigid and stable. Waffle slabs are apt for both ceiling and floor slabs. Slabs are one of the important structural components of a building. They provide a flat surface and help in transferring load. This article is about what is waffle slabs, the Construction process, Advantages and Disadvantages. 

  1. What is a waffle slab – Details and construction
  2. Waffle slab construction details
    1. In situ construction
    2. Precast
    3. Prefabricated
  3. Advantages of Waffle slab 
  4. Disadvantages of Waffle slab

What is a waffle slab – Details and construction

A waffle slab is a type of slab that is appropriate for industrial and commercial buildings. Waffle slabs are also referred to as two-way joist slabs or ribbed slabs. They have a flat top and grids on the underside. It has greater strength than flat slabs and hence is suited for longer spans. It enables both distributed and point vertical actions. The bottom layer of concrete reinforcement in waffle slabs is replaced by concrete ribs running in two orthogonal directions. Additionally, the rib depth should range from 135mm to 235mm. Because the overall depth of the floor increases as the depth of the ribs does. The structure’s lateral loading is impacted by this.

Waffle slab - supports and pods

Waffle slab construction details

The waffle slabs need only 70% of concrete and 80% of steel from the concrete and steel used for the construction of the raft slab. The construction stages of the waffle slab include the following

  • The first step is to create the forms
  • Place the formwork components in place.
  • Position your waffle pods or moulds on the shuttering. Generally, the pods are typically constructed of plastic, and they come in a variety of sizes and shapes. The size of the pod is determined by the requirements and span length. A significant number of pods are necessary for greater spans. Accordingly, the same size pods should be used for the entire slab.
waffle pods and beam supports
  • Place the support components horizontally and vertically according to the connectors.
  • Lay out the waffle pods and spacer within the formwork in a grid pattern beginning at one corner, following the instructions in the design.
  • Fix the pod corners to the framework using cube joints.
  • Position reinforcement bars on the spacers between the waffle Pods.
  • Reinforcement is added in the two directions after the formwork has been fixed.
  • Lay the top mesh out according to the design specifications, then secure it where necessary.
  • Making sure connecting ribs are filled, pour the concrete and give it a good vibrating.
  • After the setting of the concrete, remove the frames into which the waffles are embedded. Then slowly remove the waffle forms. 

The construction of a waffle slab can be done in three ways

In situ construction

This process entails placing formwork and pouring concrete over it. A slab is cast on-site in the desired size and according to the design.

Precast

Using this technique, the casting of the slab panel is done elsewhere, and it is then placed, connected, and reinforced with concrete.

Prefabricated

In this procedure, reinforcement is built into the slab panels using prefabricated steel bars. Slabs are manufactured elsewhere and brought to the location to be erected.

Advantages of Waffle slab 

  • It is suitable for large-span structures and can be achieved with less concrete and rebar than similar conventional slabs
  • They require only a fewer number of columns.
  • It possesses a higher load-carrying capacity
  • It has higher structural stability
  • They have a good aesthetic appearance. 
  • Waffle slabs are suitable for roof slabs and floor slabs.
  • Waffle slabs have high vibration control capacity
  • The construction of this slab can be done faster and easier.
  • They are light weighted 
  • They require low construction costs, Hence they are economical when compared to other conventional slabs of the same span
  • It requires only less amount concrete and can be reinforced with mesh or rebars.

Disadvantages of Waffle slab

  • Requires Expensive formwork
  • Requires skilled workmen and supervision for the construction of waffle slabs. 
  • Higher maintenance cost
  • The increase in the depth of ribs leads to an increase in the floor height.
  • This type of slab is not suitable for windy and slope areas.

Curing of Concrete – Concrete Curing Methods explained

Curing concrete is the process of preserving the requisite moisture and temperature in hardened concrete for continued hydration. Concrete’s curing is crucial for sustaining the material’s longevity and design strength. This article discusses the importance of curing and the various concrete curing methods prevailing on construction sites.

  1. Curing of concrete methods
  2. Why Curing of concrete is important?
  3. Concrete Curing time as per IS 456-2000
  4. Concrete curing methods
    1. Water Curing method
    2. Membrane Curing method
    3. Steam curing method
  5. Conclusion

Curing of concrete methods

Curing is the process of retaining moisture to allow fresh concrete to reach its intended strength in a predetermined manner through a hydration reaction. Concrete is a mixture of cementaggregates, and water in fixed designed proportions calculated based on specific strength requirements. The water to cement ratio is the most important factor in these proportions (Water cement ratio). In order to facilitate the hydration reaction, the water-cement ratio must be maintained. If the water evaporates quickly, there will not be enough water available for the hydration process. Because of this curing of concrete is required.

Curing assists in the retention of moisture until the hydration process is complete and it reaches the required strength. The American Concrete Institute (ACI) Committee 301 recommends a minimum cure duration equal to 70% of the required compressive strength. According to IS 456-2000 standards and construction norms, the curing period of 7 days/10 days is the time required to achieve at least 70% of the intended compressive strength. That is why concrete is cured for 7-10 days.

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Why Curing of concrete is important?

Perfect curing is necessary for the following reasons in order to achieve good strength and serviceability:

  • Curing prevents concrete from drying and maintains the acceptable temperature range by preventing moisture loss.
  • Curing increases the strength and decreases the permeability of hardened concrete.
  • Curing prevents the formation of cracks caused by thermal and plastic shrinkage.
  • Concrete curing maintains a strong link between the components and the reinforcement.
  • Curing can provide the desired strength and a durable concrete free of cracks.
  • Concrete curing assists in achieving high serviceability performance by improving abrasion resistance.

Also Read : Concrete Pumps Types – Application and advantages

Concrete Curing time as per IS 456-2000

According to the Indian Standard IS 456 – 2000, concrete should be allowed to cure for a minimum of seven days while using ordinary Portland cement and for a minimum of ten days while using blended cement or concrete with mineral admixtures. Additionally, it suggests that the curing time should not be less than 10 days for structures exposed to hot, dry weather and 14 days in case for or blended cement or cement with mineral admixtures.

OPC cement = 7 Days (Normal conditions) and 14 Days ( Hot and dry weather)

Concrete with mineral admixture or blended cement (PPC cement) = 7 Days (Normal conditions) and 14 Days ( Hot and dry weather)

Concrete curing methods

The curing method and time primarily depend on structure type, site conditions, and ingredient parameters. Some of the curing methods adopted in constructions sites are as follows.

  • Water curing
  • Membrane Curing
  • Steam curing

Water Curing method

Water curing is the most popular and common method adopted in construction sites. Basically, this method maintains or retains water on the concrete surface by various methods. This includes ponding, sprinkling and fogging, and saturated wet coverings or left-in-place forms.
Similarly, these methods prevent water loss from the concrete surface by continuous wetting of the exposed surface of the concrete.

Water curing
Water curing

Membrane Curing method

The basic concept of membrane curing is reducing the loss of water from the surface of the concrete. Generally, membrane curing methods uses curing compounds or impervious plastic sheets. Curing compounds are available in water-based and acrylic-based types. They form an impermeable membrane and reduces the loss of moisture.

Membrane curing /Curing compound
Membrane curing /Curing compound

Steam curing method

The steam curing process accelerates the process of strength gaining by using heat and providing additional moisture. Generally, this speeds up the early hardening process. Basically, these methods are familiar in prefabricated structures and factory-made precast components for the speedy recovery of form works.
Accordingly, Steam curing keeps the surface moist and raises the concrete temperature to speed up the strength achievement rate.

Steam curing - Precast factory
Precast factory

Conclusion

Now a days curing activity is not taken seriously and this hampers the strength and quality. Likewise, this is an activity to be done with utmost care to ensure design strength and serviceability of structures.

Intelligent transportation system – Components of Intelligent transportation system

Intelligent transportation system is a hot topic among all civil engineering subjects that has gained popularity and many countries are successfully implementing it. With the rapidly exploding population, ITS has even become a mandatory technique in all countries. Here, we are going to read through the main components of the intelligent transportation system. We will swim through the benefits of intelligent transportation system in the middle, then to uses and challenges of ITS.

  1. What is intelligent transportation system?
  2. Components of intelligent transportation system
  3. Benefits of intelligent transportation system
  4. Uses and challenges of intelligent transportation system
    1. 1. Use of cameras equipped with automatic number plate recognition(ANPR)
      1. Advantages
      2. Challenges
    2. 2. Speed violation recording cameras
      1.  Advantage
      2. Challenges
    3. 3. Cameras for recording violations of passing through red-lights at intersections
      1. Advantages
      2. Challenges
    4. 4. Equipping the transportation system with GPS
      1. Advantages
      2. Challenges
    5. 5. Use of intelligent routing systems for public transportation passengers
      1. Advantages
    6. 6.  Modern informative systems for offenders
      1. Advantages
      2. Challenges

What is intelligent transportation system?

What is Intelligent Transport System is the first step to dive in the topic. They are advanced applications which, aim to provide innovative services relating to different modes of transport and traffic management and enable various users to be better informed and make safer, more coordinated, and ‘smarter’ use of transport networks. In ITS the information and communication technologies are applied in the field of road transport, including infrastructure, vehicles and users, and in traffic management and mobility management, as well as for interfaces with other modes of transport.

Another answer to the question of what is Intelligent transportation system (ITS) is that, it is the application of sensing, analysis, control and communications technologies to ground transportation in order to improve safety, mobility and efficiency. ITS includes a wide range of applications that process and share information to ease congestion, improve traffic management, minimize environmental impact and increase the benefits of transportation to commercial users and the public in general.

Now, let me walk you through the main components of intelligent transportation system.

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Components of intelligent transportation system

Components of intelligent transportation systems

The main components of intelligent transportation system are,

1. Accurate tracking system
GPS enabled vehicles along with smartphone apps will help citizens to track buses and other vehicles.

2. Electronic timetables
Schedules of bus service should be updated in standard format which can be easily read by people and utilised by softwares.

3. Smart model to predict time of arrival
Transportation studies like that be conducted in IIT Madras, funded by Ministry of Urban Development. should be encouraged to obtain a robust algorithm to predict the arrival time of buses, which is what a citizen needs.

4. Standardisation by regulating authority

This is very important among all the components of intelligent transportation system. An authority should be set up which can standardise various components of the public transport and encourage the use of better and smart IT services in transport sector

5.Smart commuting

Latest information on traffic jams, accidents and ways for navigation

6. Mobile technology

App based technology, incentives for young technical entrepreneurs

7. Smart traffic control

Dynamic controls of traffic signals instead of current static control, automated system.

8. Scalability

The ITS should be easily applicable to 2nd tier cities so that problem of congestion doesn’t arise in the first place

9. Improved and better BRT system enacted with public participation

10. Installing CCTVs on traffic routes and in buses.

11. Creation of flyover and overbridges to eliminate need of traffic lights

12. Electronic payment of fare

13 Traveller’s advisory system like the use of advisory radio, SMS services, internet etc

14. Highway Management Systems: Use ramp metering techniques to measure and regulate by knowing the traffic entering or leaving the highway

15. Emergency Management Systems: To manage any unforeseen emergencies

16. Railroad Crossing: Gives signals about approaching rail junctions

17 Wireless communication System

18. Safe driving Support System

This includes,

a) Right turn collision prevention system

b) vehicle detection system
c) Pedestrian detection system

d) voice guidance

e) display warning

18. Electronic toll payment System

19. Computational technologie

20. Inductive loop detection and sensing technology

21.Freeway management.

Cool! Now how are these components of the intelligent transportation system benefiting transportation? Let’s see below.

Benefits of intelligent transportation system

traffic at night - Components of intelligent transportation systems

The main benefits of intelligent transportation are as follows.

  • Develop (and subsequently renew), a secure and effective revenue collection system – this has formed the backbone of the ITS
  • Develop enhanced operations management capabilities to provide reliable services and deal with disruptions
  • Provide communications for staff security
  • Provide improved passenger information
  • Obtain data for planning, resource optimisation and performance monitoring
  • To assist the achievement of the quantity and quality of the service required in the service contract with the province of Florence

• To generate the trip logs, analysis and reporting required by the province of Florence under the service contract

• To manage the daily operations, on both normal and disrupted state

• To manage the driver vehicle handovers and shift-changes

• To provide the platform for real-time and other information to passengers

• To provide the platform for e-ticketing

• To identify vehicle faults and assist rapid response

• To support demand responsive transport and other non-standard mobility services

• To generate and manage data for post-event analysis, including running time analysis, scheduling, resource optimization, and incident investigation

So, I walked you through the important benefits of intelligent transportation system.

Its time to see the results now.

Uses and challenges of intelligent transportation system

Components of intelligent transportation systems

1. Use of cameras equipped with automatic number plate recognition(ANPR)

Equip the intersections with traffic light crossing violations recording system and video surveillance cameras monitoring traffic flow

Advantages

Cameras are capable of fining any number of offending vehicles simultaneously

Challenges

  • Drivers cover the number plate of their cars daily in order to not to be fined
  • Some drivers who repeatedly pass specific passages try to destroy or damage the cameras and their equipment.

2. Speed violation recording cameras

Fixed cameras equipped with radar technology are assembled to identify and record speed violations

 Advantage

Assured of getting fined through being caught on camera, drivers rarely attempt to drive over the speed limit

Challenges

  • After identifying the locations where the cameras are installed, drivers may attempt to increase their speed in the distances between cameras, and this may cause many disturbances in traffic flow.
  • Due to the weakness of technology, identifying motorcycles is not possible in this system

3. Cameras for recording violations of passing through red-lights at intersections

Cameras are assembled at intersections  to record the red light running violations.

Advantages

A decrease in this kind of violation will have a direct effect in reducing car crashes and capital loss.

Challenges

  • In many intersections, due to the low quality of crosswalks and zebra crossings, it is really hard to determine a threshold running from which enables the driver to be known as an offender
  • As in many intersections, turning left or right is not legally forbidden, it is really a hard job to distinguish the vehicles doing so from the violators.

4. Equipping the transportation system with GPS

Position of the buses and the approximate arrival time of buses to stations can be calculated those who are speeding or using unauthorized routes can be identified

Advantages

  • Reduction of dangerous high speed of buses
  • Decreasing of delay time of journey

Challenges

  • Some drivers try to deactivate the GPS before attempting violation. They cover the GPS with aluminum foil to make it disconnected from the center.
  • Due to the need for a GPRS platform for sending the information to the center, using this system in Tehran is very expensive.
  • Due to the low average educational level of drivers and users of public transportation services, the relevant systematic training for using this system will be needed.

5. Use of intelligent routing systems for public transportation passengers

Passenger can receive information about the journey duration and the best manner of navigation after determining the origin and destination and also specifying the desired transportation mode such as metro, taxi, bus or walking

Advantages

 Decrease in delay of journeys and an increase in productivity.

6.  Modern informative systems for offenders

All fine notifications and notices for a technical test will be informed to the offenders via SMS

Advantages

  • Deliver the fine notifications to the offenders, omitting the process of printing and stuffing envelopes with fine notification
  •  Informing all offenders of their violations in an online manner, and creating a cohesive database of the offenders.

Challenges

  • As the telecommunications system and necessary infrastructure have not been completely developed, some problems in sending the SMS to offenders have been occasionally observed.
  •  Informative limitations such as length of words in SMS.

That’s it about ITS.

Continue learning!

MUST READ: Basic of civil engineering; Simple and in-depth guide

Construction Joints in concrete – Construction joint types in slabs

Construction joints in concrete are a crucial and fundamental component of civil engineering and construction. Changes in temperature and moisture can cause concrete to expand and contract. Because concrete is weak in tension, shrinkage and volume change in concrete cause cracks. The construction joints installed at strategic locations prevent the formation of cracks in concrete and the development of tensile stresses. A construction joint is a type of concrete joint used when a new section of concrete is poured next to an already set section of concrete. The purpose of a construction joint is to allow for some horizontal movement while remaining rigid against rotational and vertical movement. This article discusses the significance of construction joint types in concrete structures like slabs and pavements etc and their applications and features

  1. Construction joints in concrete – Significance
  2. Construction joints types
  3. Construction joints
  4. Expansion joints
  5. Contraction joints

Construction joints in concrete – Significance

In general, joints in concrete are strategically placed between slab and beam, wall and column, concrete floors, pavements and so on. Improper use of joints can result in defects, cracks, and the development of stresses. Construction joints can be filled or left empty. The space between joints is occasionally filled with materials like elastomers, bitumen asphalt mix, polysulphide sealents etc. Construction Joints also divide a larger span into smaller units, making construction easier. As a result, it also aids in preventing the total collapse of the structure. Depending on the type of joint, joints are installed either before or after the laying of concrete.

Construction joints types

On the basis of the functions, Joints in construction are classified into three types

  1. Construction joints
  2. Expansion joints
  3. Contraction joints

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Construction joints

Generally, construction is a time-consuming process. Construction joints separate the large concrete work into small units. This type of joint is apt for locations where the construction is stopped at the end of the day’s work. A construction joint is a type of concrete joint used when a new section of concrete is poured next to an already set section of concrete. The purpose of a construction joint is to allow for some horizontal movement while remaining rigid against rotational and vertical movement.Construction joints can be further classified into four types on the basis of the joint end. They are

  • Butt-type construction joint
  • Tong and groove type construction joint
  • Butt-type construction joint with dowels
  • Butt-type construction joints with tie bars
Concrete construction joints in concrete

On the basis of the structure, the construction joint can be vertical, horizontal and inclined. It is suitable for the construction of large slabs, irrigation channels, etc. These joints consist of keys at definite intervals. These keys help in resuming the work the next day. It also helps in uniform load distribution.

Expansion joints

Concrete tends to expand due to changes in temperature and moisture. This causes the development of cracks and leads to failure. To avoid this problem expansion joints are used. Another name for the expansion joint is the control joint. This joint allows the expansion of concrete without the development of stresses. Thus we can prevent cracks. Buildings longer than 45m typically have one or more expansion joints. The recommended c/c spacing in India is 30m. The joints are formed by leaving a space between the building components. Generally, the depth of the expansion joint is one-fourth of the slab thickness. Installation of expansion joints can be done before or after the laying of concrete. Before installing make sure to cut the joints deeply. It is apt between the bridge section, pavements, railway tracks etc. 

Concrete construction joints in concret

Contraction joints

Concrete is weak in tension, therefore contraction of the concrete induces stress leading to cracks. This occurs during the hardening of concrete. Contraction joints prevent the unnecessary development of cracks. This type of joint in construction is installed before the laying of concrete. It is apt during the construction of roads, retaining walls, floors, tunnels, canals, etc. Generally, the interval of contraction joints is between 5m to 10m. Jointing tools are used for the installation of contraction joints. If the concrete is reinforced, then contraction joints can be avoided. But in un-reinforced or lightly reinforced slabs this joint is necessary to minimise the formation of cracks. 

Construction joints in concrete

What is a Plinth beam? Plinth beam height and size

What is a plinth beam in construction? Plinth beams are horizontal structural elements that are built at the plinth level. It is the first beam built after the foundation has been completed. Furthermore, the plinth beam is an important component in a building because it serves as a foundation for brickwork as well as a moisture barrier, preventing moisture from entering the superstructure walls. The height of the plinth beam is typically 200mm to 450mm. It can be both reinforced and unreinforced.

The most important components of a building are the substructure and superstructure. The substructure is the part of the building that is below ground level, while the superstructure is the part of the building that is above ground level. The plinth level separates the substructure from the superstructure. The plinth beam follows the foundation’s construction. This article discusses what a plinth beam is, as well as plinth level, plinth beam size, and plinth beam height.

  1. What is a plinth?
  2. What is a plinth beam?
  3. Plinth beam in construction – Functions and advantages
  4. Size of plinth beam
  5. Plinth beam reinforcement
  6. Plinth beam construction

What is a plinth?

The plinth is the structural stratum that separates the superstructure and substructure of a building. All structures must have a ground floor that is 45 to 60 centimetres higher than the surrounding ground. This will prevent rainwater, dirt, and dust from entering the building. Because of this, the outer dimensions of a pedestal constructed first are slightly larger than those of the ground floor. That is referred to as the Plinth. A level or base known as a plinth is used to support superstructure walls, columns, and other structures. The plinth’s function is to distribute pressure and load evenly across a surface.

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What is a plinth beam?

A plinth beam, as the name implies, is a beam at the plinth level. It is a particular kind of beam that is situated at the bottom of a framed structure. Because it holds the columns in place, it is also referred to as a Tie Beam. A horizontal structural component that joins the columns at the plinth level of the building is called a plinth beam. It is constructed above the top of the plinth level in load-bearing walls to aid in uniform load distribution and building settlement. Plinth beams reduce the length and slenderness ratio of a column. These beams are installed to prevent foundation cracks from spreading into the structure.

The plinth beam is located at 1.5 to 2 ft above Ground Level

Plinth beams are installed to stop cracks from the foundation from spreading into the wall above when the foundation settles. Plinth beams distribute the load of the wall evenly over the foundation.

Plinth beam in construction – Functions and advantages

Following are the functions and advantages of plinth beams

  • To prevent the development of cracks from the foundation to the walls
  • For distributing loads uniformly from columns to the foundations via superstructure.
  • Prevention of differential settlement
  • To prevent the entry of dampness in the structure. 
  • For avoiding the collapse of building due to earthquakes. It is crucial to provide plinth beams in earthquake-prone areas.
  • For providing support for walls
  • To reduce the effective length of columns. 
  • Prevention of column buckling
  • To withstand lateral forces. 
  • It saves buildings by preventing differential settlement which is caused by the partial failure of substructure or by the failure of soil on which buildings are constructed.
  • It provides uniformity to buildings at the plinth level.
  • The best application of a plinth beam is to withstand outside actions such as water, tree roots, and termites which could affect the life of the plinth.
plinth beam
plinth beam

Size of plinth beam

The plinth beams are designed in accordance with IS 132920-2016. According to the IS Code, the minimum width of the plinth beam cannot be less than 250mm. The depth should be not more than 1/4 of the clear span and not less than 200mm depth. In addition, the span to overall depth should be between 15 and 18. The concrete strength of the plinth beams shall not be less than 200Mpa.

Plinth beam
Plinth beam

Plinth beam reinforcement

At the bottom of the beam, two bars with a minimum diameter of 12mm are recommended. Similarly, two bars with a minimum diameter of 10mm must be provided at the top of the plinth beams. A 25mm concrete cover should be used to protect reinforcement bars. The stirrup diameter should be at least 6mm, with a 15cm spacing.

Plinth beam construction

1) Determining the mark-up width First, the plinth level is marked. Plinth beams are usually half the width of the foundation. The skeleton is prepared after marking the width of the plinth. The beam reinforcement must then be completed prior to shuttering.

2) Formwork Installation The next step is to put up formwork. Steel, wood, or plastic must be used for formwork. By levelling the ground, you can fix the formwork properly.

3) Concrete pouring Before pouring concrete, make sure the shuttering is dry and all the joints are tight.

4) Pouring of the concrete

Before pouring concrete, ensure the shuttering is dry and all the joints are tight. Pour the concrete evenly. 

5) Curing of the Concrete

After the concrete is dried, It is cured for at least 7 to 14 days for attaining good strength and durability

5) Removal of Formwork

After curing Once the concrete is set, remove the formwork. 

Furrow Method of Irrigation – Definition, Types and Advantages

The furrow method of irrigation is a method of laying out water channels in such a way that gravity provides just enough water for suitable plants to grow. It is typically formed through the deliberate placement of ridges and furrows. The furrow method of irrigation is one of the surface irrigation methods. Straight furrows and contour furrows are subdivisions. I will explain the important details about each of them. Also, we will find out the types methods and advantages of furrow irrigation in the blog.

So, without any due let’s look into the basics of the furrow method of irrigation.

  1. What is the Furrow Method of Irrigation?
  2. Furrow spacing for crops
  3. Types of Furrow Method of Irrigation
    1. Straight furrow
    2. Contour furrow
  4. Construction of furrow method of irrigation
  5. Advantages of furrow irrigation

What is the Furrow Method of Irrigation?

In this section, you will get the answer to what is furrow irrigation. The furrow method of irrigation is a method of laying out water channels in such a way that gravity provides just enough water for suitable plants to grow. It is typically formed through the deliberate placement of ridges and furrows.

Furrow Method of Irrigation- One of the Types of Surface Irrigation
Furrow Method of Irrigation- One of the Types of Surface Irrigation
  • The furrow method of irrigation is very much used for row crops like maize, jowar, sugarcane, cotton, tobacco, groundnut, potatoes etc.
  • In this method, only one-half to one-fifth of the surface is wetted, and thus evaporation losses are very much reduced
  • A furrow consists of a narrow ditch between rows of plants.

Let’s dig deep now.

Basically, furrow lengths range from 3m or less for gardens to 500 m for field crops, with 100 to 200 m being the most common. If the furrows are too long, deep percolation losses and soil erosion near the upper end of the field may occur. Furrows are typically provided with slopes that range from 0.2 to 6%. Accordingly, to ensure surface drainage, a minimum furrow grade of 0.05% is required.

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Furrow spacing for crops

Furrow spacing for corn, potatoes, sugarcane, and other row crops is determined by the proper spacing of the plant rows, with one irrigation furrow provided for each row. But in the case of In orchard irrigation, furrow spacing is kept between 1 and 2 metres. If the spacing is kept more, it is essential to check the distribution of moisture after each watering by auger boring.

Generally, It is more effective if the spacing is increased. Accordingly, if the spacing is maintained, it is crucial to auger bore after each watering to assess the moisture distribution. Furrow depths in low-permeability soil can range from 20 to 30 cm. When irrigating root crops, it is critical to have furrows that are deep enough and streams that are small enough that water does not come into contact with the plant. Generally, furrows for row crops like cotton, tobacco, and potatoes are typically 25cm wide and 8 to 10cm deep.

That’s it about the general details of the furrow method of irrigation. Let me show you the types now.

ALSO READ: Check flooding and Border strip methods of irrigation

Types of Furrow Method of Irrigation

Depending upon the alignment, furrows may be of two types.

  1. Straight furrow
  2. Contour furrow

Straight furrow

  • Straight furrows are used where the land slope is nominal.
  • These are aligned more or less along straight lines parallel to each other and along the slope of the land.
  • These are normally adopted where the slopes do not exceed 0.6%.

Contour furrow

  • Contour furrows are practically laid along the contours. Therefore, these are not straight but are curvilinear in the plan.
  • With contour furrows irrigation, the direction of flow is across a sloping field rather than down the slope to reduce water velocity.
  • The furrows are laid out with enough grade to carry the irrigation streams. Head ditches are run across the slope or downhill using drop structures as needed, to feed the individual furrow.
  • The contour furrows method can be successfully used in nearly all irrigable soil.
  • Light soils can be irrigated successfully across sloped up to 5 per cent. Where the soils are stable and will not be cultivated, slopes up to 20 per cent can be irrigated by contour furrowing.

ALSO READ: Rainwater Harvesting Methods: Everything You Need To Know

Stored the details in the brain, right? Let me walk you through the construction method of furrows now.

Construction of furrow method of irrigation

Furrow Irrigation
Furrow Irrigation
  • Furrows are made before planting, at the time of planting or after the plants have grown large enough not to be covered up.
  • The time of furrowing depends upon the crop grown and the method of planting used.
  • Often young plants are irrigated by small furrows until a good root system is developed. Thereafter, the furrow is made larger.
  • The furrows at any stage must be large enough to carry the water needed for irrigation.
  • In most soils, crops are grown on the top of the ridge while in deep sand, it is better to have the seeding near the bottom of the small furrow.
  • An alternate method specially adapted to sandy soils is to transplant vegetables in the furrow, irrigate it once or twice and then establish furrows between the rows after plants have grown larger.
  • Furrows are made with various cultivating tools depending on the type of crop to be grown.
  • Large furrows are normally made with a double mould board plough or lister.
  • A wooden plough with furrower attachment can also be used in place of listers. Disc-drum corrugator furrower is very useful to make small size furrows in sandy soil.

ALSO READ: Concept of green building- 4 comprehensive concepts easy read!

Time to have some positivity. The advantages of the furrow method of irrigation are given in the next section.

Advantages of furrow irrigation

irrigating plants -Furrow method
Irrigating plants

In furrow irrigation, water contacts only 1/5 to ½  of the land surface, reducing pudding and crusting of the soil. Losses due to evaporation are also reduced. Evaporation losses are also reduced. Previously, cultivation is possible in heavy soil and can be adapted to use without erosion on a wide range of natural slopes by carrying furrows across a sloping field rather than down the slope. It is especially beneficial for crops that have been harmed by water contact. Similarly, Labor requirements for land preparation and irrigation are drastically reduced. Moreover, field ditches do not waste any land.

Liked the concept of the furrow method of irrigation? Let me know your thoughts in the comments.

MUST READ GOOGLE 1st RANKING POST: Road margins- 6 types of road margins in highway

Happy learning!

Glass fiber reinforcement concrete – GFRC Ingredients, Mix and Applications

Glass fiber reinforcement concrete or GFRC is made up of portland cement, fine aggregate, water, acrylic copolymer, alkali-resistant glass fibre, reinforcement, and additives. Glass fiber reinforced concrete or GFRC is a type of fiber-reinforced concrete. The glass fibres used in Glass Fiber reinforcement concrete give this distinctive compound its strength. Alkali-resistant fibres serve as the primary tensile load-carrying member, while the polymer and concrete mix holds the fibres together. It assists in the transfer of load from one element to another.

These are mainly used in exterior building façade panels and as architectural precast concrete. Somewhat similar materials are fibre cement siding and cement boards. They consist of high-strength, alkali-resistant glass fibre embedded in a concrete matrix.

In this form, both fibres and matrix retain their physical and chemical identities, while offering a synergistic combination of properties that cannot be achieved with either of the components acting alone.

Let’s get into each of them now.

  1. Glass Fiber Reinforcement Concrete – Ingredients
    1. Cement
    2. Fine Aggregates
    3. Polymers
    4. Water
    5. Glass Fibers
    6. Other Admixtures
  2. Glass Fiber Reinforced Concrete – Casting Process
    1. Spray-Up
  3. Glass Fiber Reinforcement Concrete Advantages
    1. Low weight and high strength of Glass Fiber Reinforced Concrete
    2. Freedom of shape of Glass Fiber Reinforced Concrete
    3. 3. Durability
    4. The appearance of Glass Fiber Reinforced Concrete
    5. Environment
  4. Applications of Glass Fiber Reinforced Concrete
  5. Conclusions

Glass Fiber Reinforcement Concrete – Ingredients

The main ingredients used in Glass Fiber Reinforced Concrete is as follows

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Cement

Fine Aggregates

  • The fine aggregates usually should be river sand.
  • The fine aggregates used passed through a 4.75mm sieve and had a specific gravity of 2.68. The fine aggregates belonged to Zone II according to IS 383. 2

Polymers

  • Acrylic polymer is typically preferred over EVA or SBR polymers for GFRC. Acrylic is non-retweetable, so once dry, it will not soften or dissolve, nor will it yellow from exposure to sunlight.
  • The solids content of most acrylic polymers used in GFRC ranges from 46% to over 50%.
  • Typically, the polymer dose is 4%- 7% solids by weight of cementitious material depending on the design.

Water

Ordinary tap water which is safe and potable for drinking and washing was used to produce the concrete

Glass Fibers

  • Glass fibre, also known as fibreglass is made from extremely fine fibres of glass.
  • It is a lightweight, extremely strong and robust material. Glass fibre, the most popular of the synthetics, is chemically inert, hydrophobic, and lightweight.
  • They are manufactured as continuous cylindrical monofilaments that can be cut to specific lengths or cut as films and tapes before being formed into fine fibrils with rectangular cross-sections. Glass fibers that can withstand alkalis are a crucial part of GFRC. When using the spray-up method of casting, your sprayer will automatically cut the fibers and add them to the mixture as you apply it. If you’re casting with a premix or a hybrid method, you’ll have to mix the fibres along with other ingredients.
  • Although fibre content varies, it usually ranges from 3% to 7% of the total cementitious weight. High fibre content increases strength but decreases workability. Unlike most concrete mix design ingredients, fibres in GFRC are not calculated as a percentage of dry cementitious weight. Instead, they are calculated as a percentage of total weight. As a result, calculating fibre load in GFRC mix designs becomes quite complicated. Glass fibre, when used at a rate of at least 0.1 per cent by volume of concrete, reduces plastic shrinkage cracking and subsidence cracking over steel reinforcement.

Other Admixtures

  • Other ingredients to consider include pozzolans (such as silica fume, metakaolin, or VCAS) and superplasticizers.

So, we dug deep into the inside of Glass fibre-reinforced concrete. Next, let me walk you through the advantages of GFRC.

Glass Fiber Reinforced Concrete – Casting Process

GFRC is typically cast using two methods ie: spray up and premix. Let’s take a quick look at both, as well as a less expensive hybrid option.

Spray-Up

The fluid concrete mixture is sprayed into the forms, similar to shotcrete. The process employs a specialised spray gun to apply the fluid concrete mixture while simultaneously cutting and spraying long glass fibres from a continuous spool. Spray-up produces very strong GFRC due to the high fibre load and long fibre length, but the equipment is very expensive.

Premix

Premix incorporates shorter fibres into the fluid concrete mixture before it is sprayed or poured into moulds. Spray guns for premix do not require a fibre chopper, but they can be very expensive. Premix has less strength than spray-up because the fibres are shorter and distributed more randomly throughout the mix. The cost and strength are comparitievely lesser than spray up method.

Hybrid method

An inexpensive hopper gun can be used to apply the face coat while a handpacked or poured backer mix is used to create GFRC using a hybrid technique. A thin, fiber-free face (referred to as a mist coat or face coat) is sprayed into the moulds, and the backer mix is then packed in by hand or poured in, much like ordinary concrete. This is the method most concrete countertop manufacturers employ. This is an inexpensive way to get started. However, it is critical to carefully create both the face mix and the backer mix. This is to ensure similar consistency and makeup, as well as to know when to apply the backer coat. While doing so the backer coat can adhere properly to the thin mist coat without tearing it.

This method is comparatively inexpensive when compared to other two methods. The face and backer mix are applied at different times ensure to have similar make up of mixes to prevent curling

Glass Fiber Reinforcement Concrete Advantages

The main advantages are,

Glass fibre reinforced concrete
Glass fiber reinforced concrete

Low weight and high strength of Glass Fiber Reinforced Concrete

  • Self-weight of structures decreases when Glass Fiber Reinforcement Concrete (GFRC) is used and demands on foundations are reduced.
  • GRC cladding is suitable even for very high-rise buildings and offers good performance under seismic loading.

Freedom of shape of Glass Fiber Reinforced Concrete

  • GRC is easily moldable into a wide range of shapes, including intricate grilles, panels with a double curvature and 3-D objects.
  • The high freedom of shape permits the production of structurally very efficient elements.
  • Easily cast, it can produce items with very fine details and reproduce very complex features and elements of both modern and historic buildings.

3. Durability

  • Basic reinforcement is non-ferrous and the GRC products are not susceptible to corrosion as in traditional reinforced concrete.
  • Low permeability and a very slow rate of carbonation offer protection against the corrosion of steel in adjacent reinforced concrete.
  • GFRC has an inherently high resistance to extreme exposure conditions (freeze/thaw, fire etc.)

The appearance of Glass Fiber Reinforced Concrete

  • An extremely wide range of attractive surface finishes is available.
  • It satisfies the highest requirements for an aesthetic appearance of new structures and is capable of matching the colour and texture of surfaces of existing buildings.
  • Durable and brightly coloured surfaces with enhanced self-cleaning can be achieved in a variety of textures and shapes.

Environment

  • The relatively low weight of GRC products reduces CO2 emissions associated with their transport.
  • There are no Volatile_organic_compounds or other pollutants emitted from the material itself, neither in production nor in use.
  • GRC is fully recyclable into concrete and other applications.
  • In addition, the photocatalytic E-GRC reduces directly and significantly the concentration of pollutants in the surrounding air, leading to a better quality of the environment.
  • This is good especially in congested urban centres and at a minimal additional cost.

Also read: 3 d Printing buildings |Concrete Printing & Contour Crafting Methods Full Guide

Now, how about a quick glance through the applications?

Applications of Glass Fiber Reinforced Concrete

Glass Fiber Reinforced Concrete - Fascia
GFRC Building

Due to its versatility the range of GFRC is growing.

  • All the categories of buildings have been constructed using GFRC
  • Small, simple and unsophisticated items for everyday use are made using GFRC on a large-scale
  • Architects prefer GFRC to fulfil high structural complexity, size of construction elements, and freedom of shape to achieve spectacular appearance, durability and the highest quality
  • Positive environmental performance

That’s it. Time to sum up.

Conclusions

  • GFRC has a large scope of application and research and development is going on
  • It is a very versatile material and the freedom of shape makes it the number one choice by architects
  • Glass fibre reinforced concrete is used from small scale household products to large-scale buildings of structural complexity

So, how is our buddy GFRC? Let me know your thoughts in the comments.

Also read: Shotcrete – An overview| Shotcrete vs Gunite

Happy learning!

Glass Fibre Reinforced Concrete- Fiberglass reinforced concrete Advantages

Glass Fibre Reinforced Concrete or GFRC is made up of portland cement, fine aggregate, water, acrylic copolymer, alkali-resistant glass fibre, reinforcement, and additives. Glass fibre-reinforced concrete or GFRC is a type of fibre-reinforced concrete. The glass fibres used in Glass Fibre reinforcement concrete give this distinctive compound its strength. Alkali-resistant fibres serve as the primary tensile load-carrying member, while the polymer and concrete mix holds the fibres together. It assists in the transfer of load from one element to another.

These are mainly used in exterior building façade panels and as architectural precast concrete. Somewhat similar materials are fibre cement siding and cement boards. They consist of high-strength, alkali-resistant glass fibre embedded in a concrete matrix.

In this form, both fibres and matrix retain their physical and chemical identities, while offering a synergistic combination of properties that cannot be achieved with either of the components acting alone.

Let’s get into each of them now.

  1. Glass Fibre Reinforcement Concrete – Ingredients
    1. Cement
    2. Fine Aggregates
    3. Polymers
    4. Water
    5. Glass Fibre
    6. Other Admixtures
  2. Fibre Glass reinforced concrete – Casting Process
    1. Spray-Up
    2. Premix
    3. Hybrid method
  3. Glass Fiber Reinforced Concrete Advantages
    1. Low weight and high strength of Glass Fiber Reinforced Concrete
    2. Freedom of shape of Glass Fiber Reinforced Concrete
    3. 3. Durability
    4. The appearance of Glass Fiber Reinforced Concrete
    5. Environment
  4. Applications of Glass Fibre Reinforced Concrete
  5. Conclusions

Glass Fibre Reinforcement Concrete – Ingredients

The main ingredients used in Glass Fibre Reinforced Concrete are as follows

Related contents from vinciviworld

Cement

Fine Aggregates

  • The fine aggregates usually should be river sand.
  • The fine aggregates used passed through a 4.75mm sieve and had a specific gravity of 2.68. The fine aggregates belonged to Zone II according to IS 383. 2

Polymers

  • Acrylic polymer is typically preferred over EVA or SBR polymers for GFRC. Acrylic is non-retweetable, so once dry, it will not soften or dissolve, nor will it yellow from exposure to sunlight.
  • The solids content of most acrylic polymers used in GFRC ranges from 46% to over 50%.
  • Typically, the polymer dose is 4%- 7% solids by weight of cementitious material depending on the design.

Water

Ordinary tap water which is safe and potable for drinking and washing was used to produce the concrete

Glass Fibre

  • Glass fibre, also known as fibreglass is made from extremely fine fibres of glass.
  • It is a lightweight, extremely strong and robust material. Glass fibre, the most popular of the synthetics, is chemically inert, hydrophobic, and lightweight.
  • They are manufactured as continuous cylindrical monofilaments that can be cut to specific lengths or cut as films and tapes before being formed into fine fibrils with rectangular cross-sections. Glass fibres that can withstand alkalis are a crucial part of GFRC. When using the spray-up method of casting, your sprayer will automatically cut the fibres and add them to the mixture as you apply it. If you’re casting with a premix or a hybrid method, you’ll have to mix the fibres along with other ingredients.
  • Although fibre content varies, it usually ranges from 3% to 7% of the total cementitious weight. High fibre content increases strength but decreases workability. Unlike most concrete mix design ingredients, fibres in GFRC are not calculated as a percentage of dry cementitious weight. Instead, they are calculated as a percentage of total weight. As a result, calculating fibre load in GFRC mix designs becomes quite complicated. Glass fibre, when used at a rate of at least 0.1 per cent by volume of concrete, reduces plastic shrinkage cracking and subsidence cracking over steel reinforcement.

Other Admixtures

  • Other ingredients to consider include pozzolans (such as silica fume, metakaolin, or VCAS) and superplasticizers.

So, we dug deep into the inside of Glass fibre-reinforced concrete. Next, let me walk you through the advantages of GFRC.

Fibre Glass reinforced concrete – Casting Process

GFRC is typically cast using two methods ie: spray up and premix. Let’s take a quick look at both, as well as a less expensive hybrid option.

Spray-Up

The fluid concrete mixture is sprayed into the forms, similar to shotcrete. The process employs a specialised spray gun to apply the fluid concrete mixture while simultaneously cutting and spraying long glass fibres from a continuous spool. Spray-up produces very strong GFRC due to the high fibre load and long fibre length, but the equipment is very expensive.

Premix

Premix incorporates shorter fibres into the fluid concrete mixture before it is sprayed or poured into moulds. Spray guns for premix do not require a fibre chopper, but they can be very expensive. Premix has less strength than spray-up because the fibres are shorter and distributed more randomly throughout the mix. The cost and strength are comparatively lesser than the spray-up method.

Hybrid method

An inexpensive hopper gun can be used to apply the face coat while a handpicked or poured backer mix is used to create GFRC using a hybrid technique. A thin, fibre-free face (referred to as a mist coat or face coat) is sprayed into the moulds, and the backer mix is then packed in by hand or poured in, much like ordinary concrete. This is the method most concrete countertop manufacturers employ. This is an inexpensive way to get started. However, it is critical to carefully create both the face mix and the backer mix. This is to ensure similar consistency and makeup, as well as to know when to apply the backer coat. While doing so the backer coat can adhere properly to the thin mist coat without tearing it.

This method is comparatively inexpensive when compared to the r two methods. The face and backer mix are applied at different times ensure to have similar make-up of mixes to prevent curling

Glass Fiber Reinforced Concrete Advantages

The main advantages are,

Glass fibre reinforced concrete
Glass fibre reinforced concrete

Low weight and high strength of Glass Fiber Reinforced Concrete

  • Self-weight of structures decreases when Glass Fiber Reinforcement Concrete (GFRC) is used and demands on foundations are reduced.
  • GRC cladding is suitable even for very high-rise buildings and offers good performance under seismic loading.

Freedom of shape of Glass Fiber Reinforced Concrete

  • GRC is easily moldable into a wide range of shapes, including intricate grilles, panels with a double curvature and 3-D objects.
  • The high freedom of shape permits the production of structurally very efficient elements.
  • Easily cast, it can produce items with very fine details and reproduce very complex features and elements of both modern and historic buildings.

3. Durability

  • Basic reinforcement is non-ferrous and the GRC products are not susceptible to corrosion as in traditional reinforced concrete.
  • Low permeability and a very slow rate of carbonation offer protection against the corrosion of steel in adjacent reinforced concrete.
  • GFRC has an inherently high resistance to extreme exposure conditions (freeze/thaw, fire etc.)

The appearance of Glass Fiber Reinforced Concrete

  • An extremely wide range of attractive surface finishes is available.
  • It satisfies the highest requirements for an aesthetic appearance of new structures and is capable of matching the colour and texture of surfaces of existing buildings.
  • Durable and brightly coloured surfaces with enhanced self-cleaning can be achieved in a variety of textures and shapes.

Environment

  • The relatively low weight of GRC products reduces CO2 emissions associated with their transport.
  • There are no Volatile_organic_compounds or other pollutants emitted from the material itself, neither in production nor in use.
  • GRC is fully recyclable into concrete and other applications.
  • In addition, the photocatalytic E-GRC reduces directly and significantly the concentration of pollutants in the surrounding air, leading to a better quality of the environment.
  • This is good especially in congested urban centres and at a minimal additional cost.

Also read: 3 d Printing buildings |Concrete Printing & Contour Crafting Methods Full Guide

Now, how about a quick glance through the applications?

Applications of Glass Fibre Reinforced Concrete

Glass Fiber Reinforced Concrete - Fascia
GFRC Building

Due to its versatility the range of GFRC is growing.

  • All the categories of buildings have been constructed using GFRC
  • Small, simple and unsophisticated items for everyday use are made using GFRC on a large-scale
  • Architects prefer GFRC to fulfil high structural complexity, size of construction elements, and freedom of shape to achieve spectacular appearance, durability and the highest quality
  • Positive environmental performance

That’s it. Time to sum up.

Conclusions

  • GFRC has a large scope of application and research and development is going on
  • It is a very versatile material and the freedom of shape makes it the number one choice by architects
  • Glass fibre reinforced concrete is used from small scale household products to large-scale buildings of structural complexity

So, how is our buddy GFRC? Let me know your thoughts in the comments.

Also read: Shotcrete – An overview| Shotcrete vs Gunite

Happy learning!

Los Angeles abrasion Test on Aggregates

Los Angeles Abrasion test is used to determine aggregates’ level of abrasion resistance and toughness. Los Angeles abrasion test of aggregate assesses the deterioration of aggregate standard gradings when subjected to abrasion and impact in a rotating steel drum containing an abrasive charge of steel balls. LA abrasion test on aggregates is the measure of aggregate toughness and abrasion resistance such as crushing, degradation and disintegration. Basically, finding the percentage wear as a result of relative rubbing between the aggregate and steel balls used as an abrasive charge is the primary objective of the Los Angeles abrasion test.

  1. Significance of Los Angeles Abrasion Test of aggregates
  2. Types of aggregate tests
  3. Los Angeles Abrasion tests on aggregates
    1. Codes and standards for Los Angeles Abrasion test of aggregates
    2. Working principle of LA Abrasion test
    3. The test procedure for the Los Angeles Abrasion test of aggregate
    4. The formula for LA Abrasion Test

Significance of Los Angeles Abrasion Test of aggregates

Aggregate is a fundamental and necessary component of concrete, flexible pavements, and other similar structures. More than 70% to 80% of the volume of concrete is aggregate. Quality matters when it comes to aggregates because they are the main component of concrete, flexible pavements, etc. Various tests are conducted to determine the following properties of Aggregates.

  • Strength
  • Toughness
  • Hardness
  • Shape
  • Water Absorption etc.

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Types of aggregate tests

The following are the various aggregate tests used to determine aggregate suitability:

This article is about Los Angeles Abrasion tests on aggregates

Los Angeles Abrasion tests on aggregates

The aggregate toughness and abrasion resistance such as crushing, degradation, and disintegration are evaluated by the Los Angeles abrasion test. Generally, this test is performed in accordance with AASHTO T 96 or ASTM C 131.

The Los Angeles Abrasion test determines the aggregate’s wearing resistance and hardness. Abrasion is indeed the wearing action on aggregate caused by vehicle movement. In order to resist abrasion, the aggregate should have an adequate abrasion value. The abrasion test value can ensure the quality and suitability of aggregates. Furthermore, aggregate with high abrasion resistance has a long life span.

Codes and standards for Los Angeles Abrasion test of aggregates

There are 3 tests commonly used to test aggregates for their abrasion resistance. (a) Deval Attrition Test (b) Dorry Abrasion Test (c) Los Angeles Abrasion Tests. However, Los Angeles abrasion test values are more realistic and correct.

Los angeles Abrasion testing apparatus
Los Angeles Abrasion Testing Apparatus

Working principle of LA Abrasion test

The principle of this test is to produce abrasive action using steel balls mixed with aggregates. Accordingly, the aggregate and steel balls are rotated in a drum for a specific number of rotations. The percentage of wear due to relative rubbing action between the aggregate and steel balls is recorded. This value is the Los Angeles Abrasion value.

Los Angeles Machine cross section
Los Angeles abrasion testing machine

The test procedure for the Los Angeles Abrasion test of aggregate

The Los Angeles abrasion testing machine consists of a hollow steel cylinder, closed at both ends, having an inside diameter of 700 mm and an inside length of 500 mm. The abrasive charge shall consist of cast iron spheres or steel spheres approximately 48 mm in. diameter and each weighing between 390 and 445 g. The number of balls to be placed shall be as per IS 2386.

Grading and number of abrasive charges
Grading and number of abrasive charges

The test sample shall consist of clean aggregate which has been dried in an oven at 105 to 110°C to substantially constant weight. They shall conform to one of the gradings shown in Table II.

GRADINGS OF TEST SAMPLES AS PER IS 2386PLES
GRADINGS OF TEST SAMPLES AS PER IS 2386
  • Firstly, place the specimen inside the horizontal drum.
  • Then, put the steel balls and rotate the cylinder for a total of 500-1000 revolutions at the speed of 30-33 rpm about its horizontal axis. For gradings A, B, C and D, the machine shall be rotated for 500 revolutions. However, for gradings E, F and G, it shall be rotated for 1000 revolutions.
  • After completing the specific rotations, collect the specimens from the cylinder.  
  • Then sieve on a 1.7 mm IS sieve and weigh the specimen.
  • Lastly, calculate the abrasion value using the formula below.

The formula for LA Abrasion Test

The original weight of aggregate sample = W1 g

Weight of aggregate sample retained = W2 g

Weight passing 1.7mm IS sieve = W– Wg

Abrasion value = [(weight of sample taken – weight of sample retained on IS sieve) / weight of sample taken ] x 100

The difference between the original weight and the final weight (sieved through 1.7mm) is expressed as % of the original weight of the sample aggregate. Similarly, this value is called as Los Angeles abrasion value.

Physical Properties of Cement – Significance and impacts

The physical properties of cement have a significant impact on a structure’s serviceability, strength, and durability. The most important and highly recognized structural material used in construction is cement. All types of construction, from large skyscrapers, bridges, and tunnels to modest residential structures, use cement. It stands out as a crucial component of industrial buildings such as power plants, refineries, steel plants, cement mills, bridges, and other infrastructure.

Cement, when mixed with sand and aggregates, forms concrete, and when mixed with sand, it forms mortar. The serviceability, strength, and durability of a structure are entirely dependent on the quality of cement used for concrete and mortar; similarly, the properties of cement are directly related to the Cement Manufacturing Process, which involves the proportioning of ingredients, grinding, packing, and storing, among other things.

The cement properties are classified into PHYSICAL PROPERTIES and CHEMICAL PROPERTIES

  1. Physical Properties of Cement
    1. The fineness of cement – Physical properties of cement
    2. The soundness of cement – Physical Properties of Cement
      1. Causes of Unsoundness of cement
    3. Consistency of cement
    4. Strength of cement
    5. Setting time of cement
    6. Hydration of cement – The most important Physical Properties of Cement

Physical Properties of Cement

The physical properties of cement are critical in ensuring cement quality. Let us explore the physical properties of cement in depth. Physical properties distinguish different cement blends used in construction. Some critical parameters influence cement quality. Good cement has the following physical properties and is based on the following factors.

  • Fineness of Cement
  • Soundness of cement
  • Consistency of cement
  • Strength of cement
  • Setting time of Cement
  • Hydration reaction of cement

The fineness of cement – Physical properties of cement

The Fineness of cement is the measure of the particles of cement or the specific surface area of cement. The hydration rate of cement is directly related to its fineness. The higher the fineness of cement higher the specific surface area available per unit volume of cement. ie More area is available for cement and water action (hydration). This increases the rate of hydration and early gaining of strength in concrete. Bleeding can also be reduced by an increase in the fineness of the cement. But this in turn leads to dry shrinkage which can be managed by using more water.

Fineness can be determined by using a sieve analysis test, air permeability test or a sedimentation method.

The soundness of cement – Physical Properties of Cement

Soundness refers to the ability of hardened cement paste not to shrink or expand and retains its volume. If there is any change in volume, cracks may develop and the cement can be distinguished as unsound cement. Unsound cement can affect the durability and life of the structure. Soundness can also be defined as the volume stability of cement.

The cement manufacturing quality also has a very serious impact on cement quality. Inadequate heating can leave excess lime in cement. Even though cement plants have full-fledged quality labs to check the ingredients in detail, still cement has to be checked for its soundness before being used for any structure. Le Chatelier apparatus is used to test the soundness of cement.

Causes of Unsoundness of cement

The soundness of cement is affected by the presence of excess lime and magnesia. The excess lime hydrates very slowly to form slaked lime and will affect the properties of cement. The hydration difference between free lime (CaO) and slaked lime can change the volume of concrete on hardening and these changes make cement unsound.

Excess magnesia also reacts with water and affects the hydration process making cement unsound.

Gypsum is added to control the setting time of cement. Excess gypsum can react with Tricalcium aluminate to form calcium sulphoaluminate which can expand the concrete while hardening. The addition of gypsum has to be done with utmost care or else can make the cement unsound.

Consistency of cement

The consistency of cement is the ability of cement-water paste to flow under normal conditions. The optimum water-cement ratio has to be maintained in dry mixes to make it workable. Consistency of cement is the measure of the optimum water-cement ratio of a cement paste which can allow a Vicat apparatus plunger to penetrate a depth of 5-7 mm measured from the bottom of the mould. In that case, we can consider the paste is at normal consistency. The optimum water percentage for normal consistency ranges from 26% – 33%. The standard consistency test is conducted using a Vicat apparatus.

Physical properties of Cement - Finishing concrete

Strength of cement

Cement is the material responsible for imparting strength to mortar and concrete. The cement hydrates react with water and induce strength in concrete. The strength of cement has to be checked before it can be used for work. The strength can be affected by a lot of factors like water-to-cement ratio, ingredient proportioning, curing conditions, age, etc. The cement has to be checked for compressive, tensile, and flexural strength. The strengths are measured as grades in the cement bags

The strength is determined by checking the compressive strength of the cement.

Setting time of cement

The setting time of cement starts from the point water is added to the cement to a point where the cement reacts with water and hardening of the paste. It is the time taken from the production stage to the hardening stage which involves activities like, mixing, conveying, placing, and hardening. The setting time depends on a lot of factors like the fineness of cement, water-cement ratio, chemical content, and the presence of admixtures, etc. The setting time has to be adjusted in line with the structural requirements but has to ensure that the initial settling time should not be too low and the final setting time should not be too high.

The initial setting time is when the mix starts to stiffen and attains its plasticity. The initial setting time is 30 minutes for cement.

The final setting time is when the cement hardens to a point where it can take loads. The final setting time is 10 hours.

Hydration of cement – The most important Physical Properties of Cement

For using cement in any construction work, it is necessary to mix cement with water. On mixing water with the cement, a chemical reaction happens between water and cement leading to heat generation. This process of heat generation is known as the heat of hydration. It is very critical in mass concrete work and works done in hot and humid conditions.

When water is added to cement, a chemical reaction takes place between cement and water and is called hydration. Hydration generates heat, which can control the quality of the cement and helps in maintaining curing temperature in cold conditions. While using in mass concrete the heat generation tends to be very high which can cause undesired stresses in the structure. The heat of hydration is affected mostly by the presence of C3S and C3A in cement, water-cement ratio, fineness, and curing temperature. The heat of hydration of Portland cement is calculated by determining the difference between the dry and the partially hydrated cement.

Physical properties of cement

PCC Concrete – Plain Cement Concrete – PCC in Construction

PCC concrete of Plain Cement Concrete (PCC) is without reinforcement steel. Plain cement concrete (PCC) is high in compression and very low in tension. Plain cement concrete is commonly used over the ground to keep footing reinforcement from coming into direct contact with the soil. The design mixes commonly used for Plain Cement Concrete (PCC) are 1:4:8, 1:3:5, 1:2:4, M7.5, M10 etc. PCC can also be used for grade slabs (floors) and concrete roads where the only load is compressive.

Concrete is a mixture of cement, sand, and aggregate (preferably broken stone) mixed with water in specific proportions. When poured into moulds or shuttered, the mixture consolidates over time to form a uniform mass known as concrete.

  1. What is PCC Concrete or Plain cement Concrete in construction?
  2. Properties of Plain Cement Concrete or PCC concrete
  3. Ingredients of Plain Cement Concrete or PCC Concrete
  4. Production of Plain Cement Concrete (PCC) in Construction
  5. Types of concrete in construction
  6. How to Decide On A Concrete Type
    1. Material Availability
    2. Strength Required
    3. Construction methodology to be adopted
    4. Type of structure
    5. Area of application
    6. Climate and pouring conditions
  7. Placing of Plain Cement Concrete (PCC)
    1. Level marking and dressing for PCC concrete
    2. Surface Preparation and shuttering
    3. Placing and Finishing of PCC Concrete
  8. Precautions while doing Plain Cement Concrete (PCC)

What is PCC Concrete or Plain cement Concrete in construction?

Concrete without reinforcement steel is called Plain Cement Concrete (PCC). Generally, design mixes commonly used for PCC are 1:4:8 , 1:3:5, 1:2:4, M7.5, M10 etc. Plain cement concrete is high in compression and very low in tension.

Plain cement concrete laying
Plain cement concrete laying

Properties of Plain Cement Concrete or PCC concrete

Plain cement Concrete (PCC) has compressive strengths ranging from 200 kg/cm2 to 500 kg/cm2. Likewise, tensile strength of PCC ranges from 50 kg/cm2 to 100 kg/cm2, and density ranges from 2200 kg to 2500 kg, depending on the grade of concrete and aggregates used.

Ingredients of Plain Cement Concrete or PCC Concrete

Basically, PCC is made from cement, coarse aggregate, and fine aggregate. Ordinary Portland cement is used as the binding material. Accordingly, as coarse aggregate, broken or crushed stone or brickbats must be used. However, fine aggregate must consist of coarse sand. Finally, these ingredients are combined in the appropriate proportions with potable water to make PCC.

Production of Plain Cement Concrete (PCC) in Construction

PCC can be manufactured in batching plants, mixer machines, or manually mixing. Generally, the thickness of PCC can range from 50 mm to 300 mm or more, depending on the design parameters.

Types of concrete in construction

The following are the main types of concrete used in construction

Plain cement concrete (PCC)
Plain cement concrete (PCC )

How to Decide On A Concrete Type

The type of concrete to be used on a particular work is decided based on following conditions.

Material Availability

Normally, the raw material (aggregate, sand, cement etc) availability decides the type of concrete to be used.