# Category Archives: civil engineering

All the general details about civil engineering sector are given in the civil engineering category. Basic elements in civil engineering- Foundation is the lowermost part of the building. The building activity starts with digging the ground for foundation and then building it..

# Development length formula as per IS 456

Development length is an essential concept in civil engineering that refers to the length of reinforcement required to transfer the force from the steel reinforcement to the surrounding concrete. It is crucial in ensuring that the reinforcement is effectively bonded to the concrete to resist the applied forces. “The development length depends on several factors, including the diameter of the bar and the strength of the concrete. “Another factor that affects the development length is the bond strength between the steel reinforcement and the surrounding concrete.”

Properly understanding development length is essential for designing reinforced concrete structures to ensure their safety and stability. Engineers calculate the development length to ensure that the reinforcement will provide the intended strength and reinforcement to the structure. “Insufficient development length can cause the reinforcement to fail to transfer forces to the concrete effectively. This can ultimately lead to structural failure.”

## What is the development length?

To develop the full tensile strength of the reinforcement, one must embed the reinforcement in concrete for a minimum length known as the development length. This is necessary to ensure that the reinforcement can resist the applied loads. This should happen without pulling out of the concrete or causing concrete failure.

Either pull-out or splitting failure modes typically control the length. In pull-out failure, the force applied to the reinforcement exceeds the pull-out strength of the concrete. This generally causes the reinforcement to pull out of the concrete. In splitting failure, the force applied to the reinforcement causes the concrete to crack and split. This can lead to the failure of the reinforcement.

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## Significance and functions

This is a critical concept in reinforced concrete structures that ensures the effective transfer of forces and prevents premature failure. It is important for the safety and stability of structures and is a crucial factor in their design and construction. The main function is as follows.

### Transfer of applied forces

Ensuring effective bonding of the steel reinforcement to the surrounding concrete is the purpose of the Development length in reinforced concrete structures. This allows it to transfer the applied forces to the concrete.

### Prevents structural failure:

Basically, the proper bonding of the reinforcement to the concrete prevents premature failure of the structure. This could otherwise result in catastrophic consequences.

### Important for design

Properly understanding Develop length is critical for designing reinforced concrete structures. Engineers must calculate the length to ensure that the reinforcement provides the intended strength and reinforcement to the structure.

Basically, an insufficient development length can lead to the reinforcement not being able to transfer the forces to the concrete effectively. However, this results in premature failure and instability.

### Structural safety and stability

Generally, this is crucial for the safety and stability of reinforced concrete structures. The failure to effectively bond the reinforcement to the concrete would result in the inability to transfer the applied forces. However, this can lead to structural failure.

## Factors determining Development strength

Several factors influence the required development length to fully develop the tensile strength of reinforcement in concrete, including

• Reinforcement properties: The strength and diameter of the reinforcement significantly impact the required development length. Generally, high-strength reinforcement with a larger diameter will require a longer D length to develop its full strength.
• Concrete properties: The strength, stiffness, and thickness of the concrete member where we place the reinforcement are crucial factors. However, a higher concrete strength requires a longer d length, while a thicker concrete section may require a shorter length.
• Bond strength: The bond strength between the reinforcement and concrete is critical in determining the development length. However, the bond strength depends on various factors. This includes the surface condition of the reinforcement, the degree of deformation, and the quality of the concrete surface.
• Environmental conditions: Environmental factors such as humidity, temperature, and exposure to corrosive agents can affect the bond strength between the reinforcement and concrete. In such cases, we may require a more extended development length.
• Load conditions: The type, magnitude, and direction of the load applied to the reinforcement significantly influence the development length required. Generally, Higher loads require a longer D length to prevent the reinforcement from pulling out of the concrete.
• Design codes and standards: Design codes and standards typically provide guidelines for determining the minimum development length required for different types of reinforcement and loading conditions. However, these guidelines may vary depending on the specific code or standard used.

## Development length as per IS 456

Basically, Clause 26.2.1 of the Indian code for the design of reinforced concrete structures (IS 456:2000) provides the formula to calculate the development length of reinforcement bars in tension. Basically, we require the length of the reinforcement bar to transfer the stresses between the reinforcement and the surrounding concrete.

The formula for calculating the D length (Ld) of a reinforcement bar with a diameter of D, embedded in concrete with a grade of M, and subject to tension, is as follows:

Ld = (0.87 fy A / 4τ_bd) + (0.2 √fc) …Equation 1

where:

• fy is the characteristic strength of the reinforcement in N/mm²
• A is the area of the reinforcement in mm²
• τ_bd is the bond stress between the reinforcement and the surrounding concrete in N/mm²
• fc is the characteristic compressive strength of concrete in N/mm²

The first term in Equation 1 represents the basic development length, which is the minimum length required for the reinforcement to fully develop its strength. The second term represents the additional development length due to the curvature of the bar.

It is worth noting that the code also provides alternative methods for calculation, such as the empirical equations given in Table 5 of the code. However, Equation 1 is the most widely used method for calculating the development length in India.

It is important to note that these calculations are based on certain assumptions and simplifications, and the actual development length required may vary based on the specific design requirements and site conditions.

## Development length as per IS 456 for columns, footings and beams

The dev. length of rebars is the minimum length required for the effective transfer of forces from the steel reinforcement to the surrounding concrete. However this ensures that the reinforcement is properly bonded to the concrete, preventing premature failure of the structure.

## Development length as per codes

The development length of a reinforcing bar, or rebar, is the minimum length of the bar that must be embedded or overlapped with concrete to ensure proper transfer of stresses between the concrete and steel. This is a critical design parameter, and it is determined based on various factors such as the strength of the rebar, the strength of the concrete, and the design requirements of the structure.

Here are the formulas as per some commonly used codes:

### ACI 318-19 (American Concrete Institute)

Ld = [(φ x Fy x As) / (4 x Fc’^(0.5))] x (1.3 for deformed bars, 1.7 for plain bars)

where: Ld = development length in inches

φ = strength reduction factor (0.7 for deformed bars, 0.8 for plain bars)

Fy = yield strength of rebar in ksi

As = area of rebar in square inches

Fc’ = specified compressive strength of concrete in psi

### BS 8110-1:1997 (British Standard)

Ld = [(1.2 x σst x As) / (0.87 x Fy x (1 + (200/d))^(0.5))] x (1.4 for deformed bars, 1.7 for plain bars)

where: Ld = development length in mm

σst = stress in rebar at yield in N/mm2

As = area of rebar in mm2 Fy = characteristic yield strength of rebar in N/mm2 d = diameter of rebar in mm

IS 456:2000 (Indian Standard)Ld = [(0.87 x fy x As) / (4 x τbd x fck^(0.5))] x (1.2 for deformed bars, 1.6 for plain bars)

where: Ld = development length in mm

fy = characteristic strength of rebar in N/mm2

As = area of rebar in mm2 τbd = design bond stress in N/mm2

fck = characteristic compressive strength of concrete in N/mm2

It is important to note that the development length calculation may vary based on the specific requirements of the structure, and it is recommended to consult the appropriate code for accurate and up-to-date information.

# All cement price list today 2023 – Cement Price per bag today

All cement price list today is the most important update every construction engineer and civil engineering construction firm should be familiar with. Cement is the most significant and widely used construction material which forms an integral part of any structure. Cement is the major ingredient of concrete and mortar and the structural stability and life of a structure or building depend on the cement quality.

## Significance of knowing the price of cement today

Cement is widely available on the market. Therefore, one needs to be aware of cement’s pricing before purchasing. Cement accounts for almost 20% of total construction costs. Cement is therefore one of the most expensive construction materials. One must therefore be familiar with the most recent cement price list rates that are offered on the market. Generally, cement is utilised for everything from a building’s foundation to its final touches. Because cement prices play such a significant effect on construction costs, it is necessary to consider them when making purchases.

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## Factors affecting the cement prices

Also, the price of each cement varies according to its quality. Yet, different types of cement are utilised in different locations. The following variables influence cement pricing:

• Costs of Raw Materials: The basic raw materials for cement manufacture are limestone and clay, and their prices might fluctuate based on supply and demand situations in their respective markets.
• Energy Costs: The cost of energy, such as the price of fuel and electricity, can impact cement’s cost.
• Transportation Costs: The expense involved in transporting raw materials to the manufacturing plant, as well as the cost of delivering the final product to market, can influence cement prices.
• Production Costs: The cost of production can be influenced by factors such as the cost of labour, the efficiency of the manufacturing process, and the level of competition in the market.
• Government Regulations: Government rules, such as taxes, import duties, and environmental regulations, can also have an impact on the price of cement.
• Economic Factors: Generally, economic factors such as inflation, exchange rates, and overall economic growth can all have an impact on cement prices.
• Market Demand: The level of demand for cement in a particular market can also impact its price. However, during periods of high demand, prices may be higher, while during periods of low demand, prices may be lower.
• Competition: The level of competition in the cement market can also influence prices. If there is a high level of competition, companies may be pressured to lower their prices in order to remain competitive.

## Uses of Cement

Cement is an essential element in the construction industry. It is needed to make concrete and mortar. Cement is manufactured by heating a mixture of limestone and clay to form a powder. The powder, when mixed with water, makes a paste that sets and hardens. Some of the most common applications for cement are:

• Cement is used in the manufacture of concrete. Concrete is the major building material for foundations, walls, bridges, and roadways.
• Masonry work: For laying bricks and stone, cement is used as binding material
• Plastering: Cement is widely used in the production of plaster. Plaster is used to coat the interior and exterior walls and ceilings of buildings.
• Cement can be used as a base material in the manufacture of floor screeds, terrazzo, and other flooring products.
• Dams: It is used in the production of concrete for dams, which are structures designed to retain water.
• Pipelines: Other subsurface constructions, including pipelines, are made of cement.

In summary, cement is an essential material in the construction industry and is used for a wide range of purposes, from building construction to flooring, and from masonry work to making pipes.

## Top cement companies of India with the latest price list

Here is a list of the top cement companies in India along with their latest price list:

1. UltraTech Cement Ltd. – UltraTech Cement is the largest manufacturer of cement in India and one of the world’s leading suppliers of cement and clinker. As of February 2023, the latest price of UltraTech Cement is Rs. 350 – 400 per bag
2. Ambuja Cements Ltd. – Ambuja Cements is one of the leading cement companies in India. Ambuja cement is best known for its sustainable practices and use of advanced technology. As of February 2023, the latest price of Ambuja Cement is Rs. 330 -400 per bag
3. ACC Ltd. – ACC is one of the largest cement companies in India. ACC has a strong presence in the country’s western and southern regions. As of February 2023, the latest price of ACC Cement is Rs. 330 to 450 kg bag.
4. Shree Cement Ltd. – Shree Cement is a leading cement company in India. We know that Shree cement is known for its high-quality products and innovative business practices. As of February 2023, the latest price of Shree Cement is Rs. 300 – 375 per 50 kg bag.

Please note that these prices may vary based on location and market conditions.

## Conclusion

Cement prices play an important part in the cost of every structure. Everyone related to the civil engineering and the construction industry should be familiar with cement prices. Hence it is required to be updated with cement prices regularly. Top brands are available in almost every part of the country.

# 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.

## 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).

## Calculation of weight of steel bars per Running Meter

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.

# 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.

## 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.

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

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.

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.

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.

• 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.

• 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.

• 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.

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.

# Refractory Bricks – Properties and Types

Refractory bricks, also known as firebrick are ceramic materials used to line furnaces, kilns, fireboxes, and fireplaces. A refractory brick is designed to withstand high temperatures while still having poor thermal conductivity for increased energy efficiency. Refractory bricks are used in place of regular bricks, which always have a tendency to shatter at high temperatures. These bricks may also go by the titles ceramic bricks or fire bricks. Brick is one of the most popular construction materials used since ancient times. Regular bricks tend to crack at high temperatures and are not preferred for high-temperature areas. In such conditions, conventional bricks are often replaced by Refractory bricks.

## What are refractory bricks?

Refractory brick is a type of brick that can resist high temperatures. It is also known as ceramic bricks or fire bricks. Generally, they are yellowish-white in colour. These bricks have good thermal resistance and good compressive strength. The chemical composition of fire bricks differs from regular bricks’ chemical composition. It mainly consists of 25 to 30% alumina, and 60 to 70% silica. Also, oxides of magnesium, calcium, potassium etc are present. The main application of fire bricks is in the construction of kilns, furnaces, etc. They are able to withstand temperatures above 2100 degrees Celsius. Thus the thermal capacity helps the structure to be stable at high temperatures.

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## Properties of Refractory brick

Following are the properties of Refractory brick.

• Refractory brick should resist high temperatures.
• They have good compressive strength.
• The weight of fire bricks is 150 lbs per cubic ft.
• The size of refractory brick is 9×4.5×2.5 inches or 9×2.7×2.25 inches.
• They also have good chemical resistance, Since they do not react with the furnace gases.
• The water absorption of refractory brick is 5 to 10%.
• They have a high fusion point.

## Types of Refractory bricks

Refractory bricks are available in various sizes and shapes. There mainly three types of refractory brick

• Acid refractory bricks
• Basic refractory Bricks
• Neutral refractory Bricks

### Acid refractory bricks

The acid refractory brick includes silica bricks and ganister bricks. Silica brick consists of 93% of Silicon dioxide. They possess good strength and fusion points. Also, they are hard and it is suitable for acid lining in furnaces. They can withstand temperatures up to 2000 degrees Celsius. Silica bricks are made from sandstone or quartzite. Ganister bricks consist of 85% of silica, 10% clay and 2% of lime. They are also hard and can withstand temperatures up to 2100 degrees Celsius. But acid bricks are not suitable to undergo rapid temperature. Since they tend to spall.

### Basic refractory bricks

Basic refractory bricks are basic in nature. They have good corrosion resistance and chemical resistance. They consist of Magnesite bricks, dolomite bricks and Bauxite bricks. Magnesite bricks contain 85% of magnesium oxide and 3 to 5% of iron oxide. They are suitable for the lining of the furnace. They can withstand temperatures up to 1800 to 2100 degrees Celsius. Dolomite bricks can withstand temperatures up to 1400 to 1600 degrees Celsius. It contains a high amount of dolomite. Bauxite bricks are a type of basic refractories that can withstand temperatures up to 1600 degrees Celsius and contains 85% of bauxite.

### Neutral refractory bricks

Neutral refractory bricks are suitable in places to separate the acid and basic lining in the furnace. They consist of chromite bricks, carborundum, spinal bricks and forsterite bricks. These bricks have a high percentage of chrome and magnesite.

# 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.

## Glass Fiber Reinforcement Concrete – Ingredients

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

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## Reactive Powder Concrete- 6 Components and All Properties Explained

### 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 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

### 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.

Now, how about a quick glance through the applications?

## Applications of Glass Fiber Reinforced Concrete

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.

Happy learning!