All posts by Vinod Gopinath

architectural finishes, Tiles

Types of ceramic tiles Advantages and Disadvantages

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Ceramic tiles vs Vitrified tiles – The real difference between ceramic and vitrified tile is still out of reach to a consumer. For an average consumer Ceramic tiles, vitrified tiles/ porcelain tiles, etc are simply tiles used for flooring or cladding works because all are installed in the same way, got almost identical looks, got similar merits and demerits as a flooring material. On enquiring, you may get a lot of merit claims which confuses more than clarifying.
What exactly is the difference between these tiles or is it simply a marketing technique for selling out the more costly option?

Must read : Types of Vitrified tiles

What is a ceramic tile?

The tile is a very thin flooring material made of clay, stone, metal, etc extensively used for covering floors, roof, walls, etc. Enormous varieties like ceramic tile, vitrified tile, porcelain tile, terrazzo tile, chequered tile, metal tiles, stone tiles, etc are used as flooring materials based on the area of application and requirements. The category of tiles manufactured from natural clay, mixed with other ingredients, baked in kilns, and glazed for protection and looks are called ceramic tiles. Ceramic and vitrified/porcelain tiles come under the category of ceramic tiles whereas vitrified tiles are known non-porous ceramic tiles.

Classification of tiles

Classification of tiles
CLASSIFICATION OF TILES

The classifications of tiles are mostly based on their method of manufacturing, water absorption qualities, choice of application, area of usage, strength, etc. The most commonly used tiles are ceramic and vitrified tiles or porcelain tiles. The classification criteria are the percentage of water absorption which is around 4-5% in ceramic tiles where as it is below 0.5 % for vitrified tiles. Please refer above figure for the classification of tiles.

CERAMIC TILE FLOORING
CERAMIC TILE FLOORING (credits : Kajaria tiles)

Ceramic tiles – Properties

These are the most commonly used tiles available in a lot of designs, textures, and patterns and are used for almost every flooring applications. They are durable, comparatively cheap, and strong flooring material available in a lot of designs, colours, and textures. These tiles are easy to cut and fix and consists of a glazing coating for enhancing the protection. and are widely used in residential construction due to their versatile colour choice and designs and are capable of withstanding reasonable traffic and retain the sheen and charm for an extended period if maintained properly.

Reference IS CODE = IS 15622 – 2017

Water absorption3% -6%
Breaking strengthMinimum – 1000 N
Modulus of rupture20 to 30 N/mm2
Scratch hardness (Moh scale)4 minimum

These types of tiles are not preferred in high traffic areas and outdoors due to their low density and high water-absorbing qualities.

Ceramic tile manufacturing process

Ceramic tiles are manufactured from natural clay, sand, and water. The ingredients are ground and mixed with water in the right proportions to form a paste. The mix is pressed or extruded to form a tile and passed through a drying process for imparting the strength. The pattern, design, or textures are digitally printed on the surface and sprayed with a glaze powder before passing through the kiln for the firing process.

CERAMIC TILE MANUFACTURING PROCESS
CERAMIC TILE MANUFACTURING PROCESS

In the first stage, the tiles are subjected to medium temperatures for removing the water content, and in the next stage, the kiln temperature is raised to 1000-1200 degrees. In high temperature, the glaze fuses and forms a transparent layer on the tile surface. Further, the tiles are subjected to a curing process before exposure to ambient temperature to avoid breakage.

Type of ceramic tiles

Ceramic tiles are classified into wall tiles and floor tiles. They are available in glazed and un-glazed varieties. Ceramic wall tiles are normally less durable than vitrified tile which is designed specifically for flooring. Most wall tile is glazed with a semi-gloss or matt surface. The glazed surface has a very low slip resistance and becomes slippery when wet. Therefore, glazed wall tile is much more suited for wall or counter-top applications rather than floors. Floor tiles are available in anti-skid and matt finishes which are used for flooring, bathrooms, and wet areas.

Advantages of ceramic tiles

Ceramic tiles are one of the most affordable, durable, and aesthetic flooring options in the residential construction sector. Ceramic tiles inherit a hand full of excellent properties making them the most preferred flooring options. Proper placing and regular care can maintain the charm, glaze, and sheen of ceramic tiles for a long-lasting period.

CERAMIC TILE FLOORING
CERAMIC TILE FLOORING

Water resistant & Stain resistant

Ceramic tiles got a protective glazing layer on the surface and are impenetrable to water and stains. This glazing layer also protects the designs and textures and can also resist humidity to some extent. Because of these properties, Ceramic tile is preferred for moist environments like kitchen, bathrooms, etc.

Durability

Ceramic tiles are very strong, durable, and abrasion-resistant. Proper workmanship accompanied by regular maintenance can make ceramic tiles last for years. Broken tiles can be easily replaced without damaging other nearby tiles. The glazing coating is very hard and does not dent or scratch easily. They can be used for heavy traffic areas like living rooms, office space, bedrooms, etc.

Maintenance of ceramic tiles

Ceramic tiles are stain-resistant and very easy to clean and maintain using mild detergents. Ceramic tiles got a smooth and hard surface and do not attract or absorb dust, mites, and other micro-organisms which causes allergy and other asthmatic issues. Both un-glazed and glazed tiles can provide a long-lasting resilient and essentially an easy to maintain option for your home.

Colour/texture choice and affordability

Ceramic tiles are available in countless colors as well as textures, different looks and patterns can be created with flexible tile sizes. They can also be printed to reproduce the look of many hardwoods and natural stones. They can match almost any color scheme or theme. After the introduction of digital printing technology, we can print anything on ceramic tiles.
Ceramic tiles are not so costly compared to any other type of flooring material. They are rather not cheap also. But they are affordable considering the investment and the life of the ceramic tile. They are very easy to place and maintain will last a lifetime if properly installed and cared for.

Environmental friendly

Ceramic tiles are made from clay, sand, and glass. Nowadays ceramic tiles are made from recycled industrial wastes and considered environment friendly material. Ceramic tiles have insulating properties that can make the rooms cooler in summer and warmer in winter thus reducing the energy costs.

Disadvantages of Ceramic tiles

Easy to care for and available in hundreds of styles, nonetheless there are disadvantages that should be taken into consideration when a homeowner is choosing ceramic installation for the home. On getting clarity on the drawbacks we can make an easy choice.

Tile joints

Ceramic tiles are stain-resistant and water-resistant. But Grout lines are suspectable to moisture if not sealed properly. Care should be taken in choosing the sealant and sealing of grout lines. The tile joints have to be periodically sealed to restrict moisture entry and increase the tile life.

For installation, we need skilled workers to maintain the level and alignment. A proper laying is the most important factor deciding the tile life.

Ceramic tiles got a wide variety of colours and shades and the shades’ textures and style and choice of interiors tend to change with time. Once a ceramic tile is installed, replacing it will be a messy and costly option. Replacing a broken tile needs highly skilled workers and tools or else chance of breakage of nearby tiles will happen.

Ceramic tiles are very cold and it is very uncomfortable in winter times to stand on the tile. Area rugs has to be provided to cover up the area. Ceramic floors also retain heat during summers.

These tiles are denser and heavier than other flooring materials. They give extra dead load on the structure.

Conclusion

Considering the unique properties, added with a wide choice of colours and shades, and excellent resistance to stain and moisture, easy to clean and maintain Ceramic tiles are the most preferred flooring choice.

Video : Difference between Vitrified and ceramic tiles

geotechnical

Types of deep foundation – A detailed overview.

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Types of Deep Foundation – Foundations are broadly classified into shallow foundations and deep foundations. This article is a total overview of Deep Foundations and types of Deep Foundations.

What is a deep foundation?

The foundations having the depth more than the width are called deep foundations. Deep foundations are proposed when the sub soil strata lacks the safe bearing capacity to handle the loads induced by the structure. In such a case the founding level of the foundations are moved to a deeper area with required bearing capacity. The loads on the structure are transferred vertically into the ground.

Deep Foundations

Deep foundations are preferred when the subsurface bearing capacity of the soil is not competent to withstand the proposed loads coming on the structure. In that case, the loads are transferred to a designated design depth or rock/hard strata. The strata is at a deeper location below the ground level capable of negotiating the loads without failure.

Typical section of Deep Foundation
Typical section of Deep Foundation

Types of Deep Foundation

Deep foundations are adopted for many applications. They are preferred as the safest option for transferring heavy loads on soil strata with less bearing capacities. Common types of Deep foundation in use are as follows.

  • Basement foundations
  • Caissons Foundation
  • Hollow Box Foundation or Buoyancy foundations
  • Drilled shaft foundations
  • Pile foundations

Types of deep foundation – Basement foundations

Basement foundations are substructure foundations designed to account for parking areas, underground tanks, Electrical systems, and storage spaces beneath a building below ground level. They are mostly adopted in high rise residential buildings and commercial buildings. Basement foundations cater to the functional requirements of parking and storage.

Also Read : Types of Foundations- Shallow and deep foundations

Also Read : Types of shallow Foundations – Advantages & Suitability

Caissons foundation

Caisson foundation is a water-retaining structure that serves as a working space to work on the foundations of piers. They are box-type structures made of timber, steel, concrete, etc. Caisson Foundation is sunken by excavating the earth within the foundation. Caissons are prefabricated above the ground level or water level and are sunk to the founding level as one single unit. They are constructed to facilitate excavation and related works for foundations of the dock structure, bridges, jetty, piers, foreshore protection, etc. These structures later form an integral part of the main structural components.

Hollow box foundation or Buoyancy foundations

The concept of a hollow box foundation is to design a structure with minimal or no impact on the original stress of soil before commencing excavation. Required overburden as per the design is removed and superstructure loads are transferred to the ground. These types of foundations are known as Buoyancy foundations because they adopted the principle of a ship floating in the water, where the displaced water equals the weight of the ship.

Drilled shaft foundation

The drilled shaft is a versatile foundation system used extensively nowadays. These foundations are also known as a drilled pier, drilled caisson, bored pile, etc. The basic concept is excavating a cylindrical shaft and casting after putting necessary reinforcements. Diameters ranging from 1-3 mtr and depths up to 100 mtrs are preferred for drilled Shafts can be drilled from diameter ranging from 1 to 3 mtr and a depth of 100 mtrs normally. But higher depth and diameter are also possible nowadays. These types of foundations can replace driven piles to some extent where a single drilled shaft can replace a group of pile.

Pile foundations

Pile foundations are long slender members, which can be concrete, steel or any other material used for transferring the loads of a structure when the subsoil lacks the bearing capacity . The pile foundations transfer the load vertically through the less denser top layer to a high denser soil/rock layer which can negotiate the loads without failure.

Must Read : Pile foundations Classification,Types and Advantages

Typical Cross Section of Pile foundation
pile foundations

Video showing different types of shallow foundations

architectural finishes, Tiles

Types of Vitrified tiles – Advantages and Uses

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Types of vitrified tiles – Vitrified tiles are ceramic tiles with less porosity. Various types of vitrified tiles are available for catering to different functional requirements. Vitrified tiles are considered as a superior quality tile compared with ceramic tiles because of their excellent water-resistant and frost-resistant qualities, aesthetic looks, and durability. They are well suited for external and internal flooring and cladding applications and are used as an alternative to marble and granite.

What are vitrified tiles?

Tiles are classified into vitrified tiles and ceramic tiles. Vitrified tiles are manufactured by mixing clay with silica, quartz, and feldspar, pressed and heated in kilns whereas ceramic tiles are made from natural clay, moulded, and heated in kilns. The high pressure applied during the hydraulic pressing followed by the Vitrification process is responsible for imparting the superior qualities in vitrified tiles.

Vitrified tiles can withstand abrasion and maintain the surface quality and charm for several years. Vitrified tiles are available in a variety of patterns, designs, textures, and types and can match any colour schemes. Hence they are preferred for numerous applications in residential, commercial, and industrial works.

Vitrified tile flooring
Vitrified tile flooring

Also read : Ceramic tiles – Types and uses

Vitrified tiles manufacturing process

Vitrified tile is made by hydraulic pressing a mixture of clay, quartz, feldspar, and silica. The hydraulic pressed tiles are heated in kilns at a temperature of around 1000-1400 degrees centigrade. The ingredients like Quartz, silica, and feldspar melts and transforms into a glass-like hard layer. This process of manufacturing is called the vitrification process which means making like glass. At high temperatures, the molten silica fills the gaps and air bubbles thereby making the surface extremely strong and non-porous. The manufacturing process is the one that makes vitrified tiles a much superior option to ceramic tiles. The vitrification process makes vitrified tiles dense, non-porous, abrasion-resistant, and durable than ceramic tiles.

Properties of Vitrified tiles

  • Vitrified tiles are superior flooring materials and are available in a wide range of textures and shades and posses a lot of unique qualities.
  • They are available in a wide range of colours, shades, and textures and can match any interior colour scheme of the structure.
  • Vitrified tiles are durable, dense, non-porous, and strong material. They have a Flexural strength of around 35 N/ mm2 and breaking strength of around 700 N.
  • Water absorption of vitrified tiles is less than 0.5% due to its non-porous quality. Hence they are preferred for external and wet areas.
  • Ceramic tiles have to be glazed whereas vitrified tiles do not need any glazing. The vitrification process transforms the surface into a glass-like layer.
  • Vitrified tiles look aesthetically elegant with a smooth texture and glossy looks. Vitrified tiles do not fade easily and can maintain the charm and looks for an extended period.
  • Due to the vitrification process, they possess high abrasion-resistant qualities and are preferred for high traffic areas.
  • Vitrified tiles are very easy to fix and generates less wastage due to its high breaking strength. They are very easy to clean and maintain due to its high stain-resistant properties.
  • Vitrified tiles are anti-skid and possess anti-bacterial qualities.

Also read : Difference between Vitrified tile and ceramic tiles

Types of Vitrified tiles

Vitrified tiles are available in a wide range of variations to cater to any functional requirements and costs. They can cater to high traffic areas like airports, metro stations, railway stations, industrial uses, etc to small residential uses. The category and types of vitrified tiles are tailor-made for adapting to any application.

CLASSIFICATION OF VITRIFIED AND CERAMIC TILES

Vitrified tiles are broadly classified into

  • Soluble salt vitrified tiles
  • Glazed vitrified tiles,
  • Double charge vitrified tiles
  • Full body vitrified tiles

The classification is based on the method of manufacturing, method of vitrification, material qualities, density, type of traffic, color choices and functions.

Also read : Ceramic vitrified tiles: Sizes, Finish,price comparison & applications

Soluble salt vitrified tiles

The liquid screen printing technique is used for soluble salt vitrified tiles. The single colour of soluble salts provides the colour layer on the surface of the tiles. These tiles are heated in a kiln and polished for use. The main problem with soluble tiles is that the colour fades gradually and losses the original sheen and looks very dull. Colour choice is very limited for Soluble vitrified tiles and is replaced by double charge vitrified tiles having much more flexibility in terms of colour and design choices. Soluble salt vitrified tiles are normally ivory colour based tiles.

Glazed Vitrified tiles (GVT)

Glazed vitrified tiles are vitrified tiles with glazing. These tiles are very much similar to ceramic tiles. Due to the vitrification process involved in the production method, they possess high strength, durability, and excellent water repellent qualities.

Type of GVT tiles are Digital Glazed Vitrified tiles (DGVT) and Polished Glazed Vitrified tiles (PGVT tiles)

Also Read : Difference between Digital Glazed Vitrified Tiles and Double charge Vitrified tiles.

Digital Glazed Vitrified tiles (DGVT)

Glazed vitrified tiles uses digital inkjet printing technology and hence it is called Digitally glazed vitrified tiles. Due to the involvement of digital printing technology the design choices are unlimited and can print rich textures and designs over the tiles. Marble patters, wood patters and anything can be print on the tiles using digital inkjet printing technology. This is only possible in the case of Glazed vitrified tiles.

The digital designs are printed on a 1mm – 2 mm thick glazing layer which provides the required protection and long-lasting charm to the tiles. These tiles are comparatively cheap and can be used for medium traffic residential and commercial applications. This is the most commonly used tiles now a days.

These tiles may scratch and fade in long run due to the lesser top layer bearing the textures and prints.

DIGITAL GLAZED VITRIFIED TILES
DIGITAL GLAZED VITRIFIED TILES

Polished glazed Vitrified tiles (PGVT)

Digitally glazed vitrified tiles are further polished for extra glossiness. Then the tiles are known as Polished Glazed Vitrified tiles. These tiles are mostly used for residential and commercial applications involving moderate traffic.

Double charged Vitrified tiles (DCVT)

Double charged vitrified tiles are also called double-loaded tiles. They are made from a mixture of clay, quartz, feldspar, and silica. They do not have a glazed layer and hence digital printing is not possible in these tiles. For Double charged vitrified tiles the designs are formed with a double layer of pigment having a thickness of 3-4 mm thick. That means the upper layer of the design mix is 3-4 mm thick and contributes almost 30% of the total tile thickness. These layers are pressed and fused to become a part of the tile body and not a layer as in Glazed Vitrified tiles. The tile surface is further nano-polished for making it non porous, extremely durable and abrasion-resistant with superior qualities.

Double charged vitrified floor tiles are by far the most preferred choice in flooring for Residential, commercial and industrial projects  because of the simple reason that they can withstand heavy traffic and need extremely low maintenance and last longer and gives a fresh look  when compared to Ceramic and Glazed Vitrified tiles. They are scratch resistant and abrasion resistant and can resist all climatic conditions.

Full Body Vitrified Tiles

This type of vitrified tiles has colour all the way throughout the body (thickness) of the tile. Because of this scratches are less noticeable in this type of tiles. Full body vitrified tiles are formed with the paint mixture pre-added while making the body. The design is in the total thickness of the tile and got a uniform shade through out the tile body.

FULL BODY VITRIFIED TILES
DESIGN IN THE TOTAL THICKNESS

Design will never fade because it is spread over the entire body of tiles. Full body tiles are ideal flooring choice for heavy traffic areas, industrial structures, airports etc. These tiles are less preferred in residential construction due to their higher costs.

Conclusion

All types of vitrified tiles are good when chosen based on the functional requirements.

CONCRETE, Water Cement Ratio

Water to cement ratio – An Important Strength Factor.

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Water to cement ratio is the ratio between the weight of water to the cement weight used in a concrete design mix. The water to cement ratio can significantly impact the workability and strength of the concrete.

Water to cement ratio – Significance

Concrete is manufactured by mixing cement, aggregates, and water in designed proportions. The process of proportioning is done as a volumetric (nominal mix) or by weight (design mix). Cement is the main ingredient of the concrete and acts as a binding material. In combination with water, cement undergoes a chemical reaction leading to the formation of thick and sticky gels responsible for the adhesion between the ingredients. The chemical process is called the heat of hydration. Cement and water are the most important ingredients of concrete and their ratios have a huge impact on the quality and strength of concrete. So for a design mix of required strength, the ratio of water to cement has to be maintained in the right proportions.

workability
CONCRETE POURING

Water-cement ratio – Calculation

Cement requires 23% water for initiating the chemical reaction and another 15% for the formation of gel to fill the voids.38% percent by weight of water to cement ratio is essential for the complete hydration process.

Table 5 - IS 456
Table 5- IS 456

As per IS 10262, the water-cement ratio varies from 0.4 to 0.6 based on exposure conditions. For the calculation of water to cement ratio, we need the cement content of the design mix. The minimum cement content is to be confirmed from IS 10253 for different grades.

For Mix 1:2:4 Moderate exposure condition water requirement would be-

Plain concrete(moderate) Table 5 IS 10252

The Minimum cement content for M15=240 kg/ m3

and Min water cement ratio =water/cement =0.60

=water/240=0.60

Min water requirement for mix=240*.60=120 liters

For Design mix, the W/C Ratio will depend upon the workability, strength requirements.

Fig 1 - IS 10262
Fig 1 IS 10262

Water-cement ratio effect on the workability of concrete

The water cement ratio has a huge impact on the workability and strength of the concrete. The workability of concrete means the ability of concrete to perform a concreting process involving mixing, transporting, placing, compacting with ease, and without any segregation. In other words, the workability of concrete indicates the ability of concrete to work easily. W/C ratio is also an important consideration for the workability of concrete. A high w/c ratio leads to higher workability because inter particle lubrication is increased. Similarly, a lower w/c ratio leads to lower workability because there is a lack of inter particle lubrication. However the w/c ratio is not the only parameter that decides the strength of concrete. The strength of concrete depends on a lot of factors like aggregate quality, cement proportions, etc.

Also Read : QUALITY TESTS TO BE DONE ON CONCRETE- SLUMP TEST

Effect of high w/c ratio

A high w/c ratio leads to higher workability because inter particle lubrication is increased. However, the overall concrete strength is reduced with the increase in the w/c ratio. The addition of more water gives dilute paste that has more pores at the micro-level and segregation of concrete.

HOW TO FIND OUT WATER CEMENT RATIO FOR DESIGN MIX AND NOMINAL MIX

The aggregates and cement particles take the excess water that is present in concrete. This consumption is uncontrollable if a large excess of water is present in the concrete. Hence, separate water channels are created resulting in bleeding on the surface. This creates weak zones in concrete that are susceptible to cracking under service loads. Concrete with a higher w/c ratio is also more susceptible to cracking and shrinkage. Shrinkage leads to micro-cracks, which are zones of weakness.

Once the fresh concrete is placed, excess water is squeezed out of the paste. When there is a large excess of water, that water bleeds out onto the surface. The micro-channels and passages that were created inside the concrete to allow that water to flow become weak zones. These weak zones are responsible for shrinkage cracks and micro-cracks when applied with service loads.

Concrete placing
Concrete placing

Effect of low w/c ratio

Lower water to cement ratio can contribute to high strength and high-quality concrete. For higher-strength concrete, lower ratios are used, along with a plasticizer to increase flowability. But the w/c ratio alone cannot give good concrete. A good mix proportion and quality aggregates and binding materials contribute to a good mix design. A low w/c ratio is hence one of the factors influencing good mix design.

Using low w/c ratio is the usual way to achieve high strength and high-quality concrete, but it does not guarantee that the resulting concrete should possess sufficient strength. Unless the aggregate gradation and proportion are balanced with the correct amount of cement paste, excessive shrinkage, cracking and curling can result. Good concrete results from good mix design and low w/c ratio is just a part of a perfect design mix.

geotechnical

Types of shallow foundations – Advantages & Suitability

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Types of shallow foundations – Foundations are broadly classified into shallow foundations and deep foundations. This article is a total overview of shallow foundations and the types of Shallow foundations.

What is a shallow foundation ?

Shallow foundations transfer the load laterally to the soil. It is also called stripped foundations. The depth of a shallow foundation is less than its width. Shallow foundations are adopted when the load acting on a structure is reasonable and has a competent soil layer capable of negotiating the loads available at a shallow depth or shorter depth.

A shallow foundation is placed on the surface of the ground. The depth of a shallow foundation can range anywhere between 1 meter to 3.5 meters and sometimes more. The width of the shallow foundation is greater than the depth.

  1. What is a shallow foundation ?
  2. Types of shallow foundations
    1. Shallow foundation – Spread footing or isolated footing
      1. Simple spread footing
      2. Sloped spread footing
      3. Stepped spread footing
    2. Types of shallow foundations- Strip footing
    3. Types of shallow foundations – Combined footing
    4. Strap footings
    5. Mat or Raft foundations
  3. Types of shallow foundations – Suitability

Types of shallow foundations

There are different types of shallow foundations adopted as per site conditions and design requirements.

Shallow foundation – Spread footing or isolated footing

The spread footing is one of the most commonly used types of shallow foundations. They are also called isolated footing or individual footings. Spread footings are further classified into simple spread footing, sloped spread footing, and stepped spread footing based on the shape of the footing.

  • Simple spread footing
  • Sloped spread footing
  • Stepped spread footing

Simple spread footing

This is a common type of spread footing. Simple spread footing consists of a base footing with a single column over it. This type of foundation is used for structures with reasonable loads and bearing capacities.

Types of Shallow Foundations-Simple Spread Footing
Types of shallow Foundations -Isolated or spread Footings.
Types of shallow Foundations -Isolated or spread Footings.

Sloped spread footing

In this type of foundation the footing is sloped as shown in the figure. The footing carries a single column. The cross section of these types of footings are trapezoidal.

Types of Shallow Foundations-Sloped Spread Footing
Sloped Spread Footing
Sloped Spread Footing

Stepped spread footing

When the loads are high steps are provided in the footings as shown in the figure.

Types of Shallow Foundations-Stepped Spread Footing
Stepped Spread Footing

Types of shallow foundations- Strip footing

Strip footings are also called wall footings. They are used for providing load-bearing brick/stone/RCC walls over the footings. Strip footings run continuously throughout the wall area of a building. These types of footings are also used when the spacing between the columns is very less and the footings overlap each other.

Types of Shallow Foundations-Strip Footing
Strip Footing
Types of Shallow foundation : Strip Footing
Types of Shallow foundation : Strip Footing

Types of shallow foundations – Combined footing

Combined footing consists of two or more columns over a single footing. These types of footings are adopted when the distance between the two individual footings are very less and overlap each other. A combined footing is also provided in areas where further excavation is not possible due to any flushing with the boundary. A combined footing is classified as rectangular combined footings and trapezoidal combined footings.

Trapezoidal Combined Footing
Trapezoidal Combined Footing
Rectangular Combined Footing
Rectangular Combined Footing

Strap footings

Strap footings are also called cantilever footings consisting of two individual footings connected through a beam strap. The beam strap is designed as a rigid structure. These types of foundations are economical than combined footings.

Strap Footings
Strap Footings
Shallow foundation types : Strap Footing
Shallow foundation types : Strap Footing

Mat or Raft foundations

Raft foundation – One of the most commonly used types of foundation in construction is a continuous slab resting on the soil and covering the total area of the proposed structure. There are different types of raft foundations based on their applications. The selection of the type of raft foundation depends on a lot of factors like bearing capacity, loads, site conditions, etc.

Raft Foundation
Raft Foundation
Raft Foundation

Raft foundation/Mat foundation is a solid slab placed at a designed depth spreading over the entire area of the structure. Raft foundations consist of columns and shear walls for transferring loads coming on the structure to the ground. These types of foundations are mainly used when the bearing capacity of the soil is low and becomes difficult for individual footings to negotiate the loads. The raft foundation helps to transfer the entire load of the structure to a larger area.

Also read : RAFT FOUNDATION – TYPES & ADVANTAGES

Also read : PILE FOUNDATIONS – TYPES & ADVANTAGES

Types of shallow foundations – Suitability

Shallow foundations are very easy to construct and do not require highly skilled manpower and professional supervision. These foundations can even be done with the help of medium-skilled workers. A shallow foundation is very economical when compared with a deep foundation. Shallow foundations are end bearing type foundations that transfer loads to the end of the foundation.

Shallow foundations are considered as the most preferred option when the safe bearing capacity of the soil is reasonable and the structural loads are within the permissible limits.

VIDEO – SHALLOW FOUNDATIONS – DIFFERENT TYPES & ADVANTAGES

AAC blocks

AAC blocks vs red bricks – An ultimate comparison.

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AAC Blocks vs red bricks – AAC blocks are also known as Autoclaved Aerated Concrete Blocks. They are lightweight, load-bearing, durable, and economical. AAC blocks can be manufactured to meet any requirements. AAC blocks are considered a green option instead of red bricks. They have enormous potential in terms of insulation, fire resistance, and thermal resistance. AAC blocks are environmentally friendly. They are a superior material compared to concrete, wood, brick, and stone. They can enhance the construction speed, reduce the costs, and unwanted wastage at construction sites.

Autoclaved Aerated Concrete blocks are superior to conventional red clay bricks in a lot of factors. Considering the impact and necessity of these factors we can easily make a choice.

  1. AAC blocks vs red bricks
    1. Availability of sizes.
    2. AAC blocks vs red bricks- Technical properties
    3. AAC blocks vs red bricks – Construction speed
      1. Factors influencing construction speed
    4. Savings in labor
      1. Labour saving in mortar mixing
      2. Conveying and re-handling labour
    5. Material saving
      1. Saving in mortar
      2. Saving in plastering

AAC blocks vs red bricks

AAC blocks are superior to red bricks in a lot of factors relating to quality, speed, workability, cost, and wastage. There is much to discuss about the advantages of AAC blocks. They hold benefits over Red bricks, fly ash bricks, Cement Concrete hollow blocks, and CLC blocks.

AAC blocks are manufactured from materials like sand, fly ash, lime, and cement. They are lightweight, eco-friendly, and energy-efficient. Their efficiency is due to 80% voids and the use of industrial waste.

AAC blocks are superior to conventional bricks for several reasons. They are lightweight and have eco-friendly properties. These blocks offer better insulation and energy efficiency. They also utilize waste materials like fly ash.

Let us have a comparison between AAC blocks and red bricks in terms of following parameters.

  • Availability of sizes
  • Technical Properties
  • Construction speed
  • Savings in labour
  • Material Savings

Availability of sizes.

Customization in size is the most important aspect in deciding the choice of bricks/blocks for a particular structure.

AAC blocksConventional red bricks
AAC blocks are available in varied sizes are can be customised for special requirements.Mostly available in one or two standard sizes. No customisation is possible.

AAC blocks vs red bricks- Technical properties

AAC BLOCK DIMENSIONS
AAC BLOCK DIMENSIONS
RED CLAY BRICK DIMENSIONS
RED CLAY BRICK DIMENSIONS
AAC BlocksConventional Bricks
AAC blocks are available in 600 mm/625 mm (length) X 100–300 mm (height) X 230/240 mm (width).Bricks are available in 225 mm (length) X 115 mm (width) X 75/70 mm (height).
The dimension tolerance of the AAC block is +/- 5 mm.The dimension tolerance of brick is +/- 5 mm to +/- 15 mm or more.
Density ranges between 500-650 kg/cm³.Density ranges between 1400-1900 kg/cm³.
The drying shrinkage of AAC blocks is 0.4%, which is very low compared to conventional bricks.The drying shrinkage of bricks is 0.8%, which is comparatively high compared to AAC blocks.

AAC blocks vs red bricks – Construction speed

AAC blocks are considered cost-effective and economical in comparison with conventional bricks. The cost-effectiveness of AAC blocks is mostly related to the construction speed.
AAC blocks can enhance construction speed when compared to conventional bricks. This improvement is due to some unique characteristics detailed out in the following table.

AAC blocks vs red bricks
AAC blocks vs red bricks

Let us take a wall of 3mtr x 3 mtr size and 4 inch thickness

AAC BlocksConventional Bricks
Area of BlockArea of Brick
Area of block = 24 inch x 9 inch (600 mm x 230 mm) = 0.138 sqmArea of brick = 9 inch x 3 inch (230 mm x 70 mm) = 0.0161 sqm
Wall area = 3m x 3m = 9 sqmWall area = 9 sqm
No. of blocks = 9 sqm / 0.138 sqm = 65 blocks (600 mm x 230 mm x 100 mm)No. of bricks = 9 sqm / 0.0162 sqm = 555 bricks (230 x 110 x 70 mm)
Total Mortar JointsTotal Mortar Joints
85 rmt (approx)170 rmt for 4-inch wall & 240-250 rmt for 9-inch wall
WeightWeight
Weight of an AAC block (9 inch) = 16-17 kgWeight of brick = 3-3.5 kg (approx)
1 no. 9 inch block = 14-15 bricksBricks are heavy

From the above comparisons, it is clear that the AAC blocks are lightweight and covers more area than bricks. Brick masonry got 3-4 times higher mortar joints and around 14-15 bricks constitute an AAC block. That is why Brick masonry is very slow.
AAC blocks are big, got fewer joints, and can be completed very fast.

Factors influencing construction speed

Factors Influencing Construction SpeedAAC BlocksBricks
Dimensional AccuracyAAC blocks are factory-made and possess dimensional accuracy, making them easy to place and plumb.Red bricks are locally made, irregular, and less dimensionally accurate, making them difficult to place, level, and plumb.
Number of JointsAAC blocks have fewer joints, increasing construction speed.Red bricks have 4 times more joints than AAC blocks, significantly reducing construction speed.
Coverage AreaAAC blocks cover a larger area.Bricks cover a smaller area.
Skill RequirementAAC blocks can be placed by semi-skilled workers due to their dimensional accuracy and shape.Brickwork requires skilled masons because of inaccuracies and shape issues.
Mortar JointsAAC blocks use ready-mix block adhesive with a joint thickness of 3-5 mm.Brickwork uses site-mixed mortar with a minimum joint thickness of 10 mm.

Savings in labor

Savings in LaborAAC BlocksBricks
Pre-curing and post-curing laborAAC blocks do not require any pre-curing. AAC block masonry joints are air-cured and do not require any curing. Infrastructure and labor involved in the curing process can be eliminated.Bricks must be soaked in water before use. Additionally, 7-day curing is required for brickwork, which demands curing infrastructure and labour involvement.

Labour saving in mortar mixing

Labour Saving in Mortar MixingAAC BlocksBricks
Mixing ProcessAAC blocks use ready-mix bonding adhesive as jointing material, available in 25-30 kg packs and mixed with water before use.Brickwork uses site-mixed mortar that involves handling, mixing, and conveying of raw materials and mortar.
Labour CostThis can save substantial labour costs incurred for mortar mixing and conveying.Extra labour costs involved for mortar mixing and conveying.
Mortar mixing
AAC BLOCKS VS RED BRICKS – MORTAR MIXING

Conveying and re-handling labour

Conveying and Re-handling LabourAAC BlocksBricks
Supply and ConveyingAAC blocks are supplied in pallets. They can be easily lifted and conveyed to work spots using cranes and tower cranes directly from the trucks.Bricks are supplied loose and unloaded manually. They need to be filled in buckets for lifting to heights, requiring more labour.
Labour and WastageSaves labour in unloading, conveying, and lifting. Less handling generates zero wastage.Brick shifting and conveying involve heavy labour and generate a large amount of wastage.

AAC block work rates are comparably less than brickwork due to the saving involved in the labour part. The rate per cum of AAC blocks will be around INR – 650/- to -750 /- per cum whereas brickwork is around INR 1400-1500/- per cum.

Material saving

Saving in mortar

AAC blocks got fewer mortar joints of 3-5 mm thickness whereas brick masonry generates 3-4 times higher number of joints of 12 mm thickness. This can save substantially in terms of jointing material.

Analysis of Mortar for Brickwork

DescriptionQuantityxRate (INR)=Cost (INR)
1 CUM Brickwork = 0.35 to 0.4 CUM mortar
Sand cost (Rs. 2500/- per CUM)0.35x2500=875
Cement1.3x300=390
Total cost per CUM of brickworkINR1265/-

Analysis of Block Adhesive

DescriptionDetails
1 CUM block work30 kg of block adhesive
Rate per kgRs. 12-15 per kg
Cost for 30 kgAround INR 400/- per CUM

Conclusion:
Block adhesive costs approximately INR 400/- per CUM, whereas mortar costs around INR 1250/- per CUM.

Saving in plastering

AAC blocks are dimensionally accurate and both faces of the block-work look even without any undulations. The undulations can be levelled by providing a minimum plastering thickness of 10 mm inside and 12-15 mm outside. AAC blocks can even be painted by directly applying putty/Gypsum plaster over it.

Brickwork has a fair face and unfair face. To cover up undulations, a 12 mm plastering thickness is required for the fair face. A minimum of 18 mm thickness is needed for an unfair face.

AAC blocks offer other value-added benefits. They are superior in fire resistance, termite resistance, and thermal resistance. Additionally, they serve as a green building material. Please read ADVANTAGES OF AAC BLOCKS.

Also read : MANUFACTURING PROCESS OF AAC BLOCKS