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
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.
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 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.
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 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.
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.
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
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.
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.
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.
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
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
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.
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
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.
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.
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 -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.
Sloped Spread Footing
Stepped spread footing
When the loads are high steps are provided in the footings as shown in the figure.
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.
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
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.
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/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.
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.
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.
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 blocks
Conventional 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
RED CLAY BRICK DIMENSIONS
AAC Blocks
Conventional 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
Let us take a wall of 3mtr x 3 mtr size and 4 inch thickness
AAC Blocks
Conventional Bricks
Area of Block
Area of Brick
Area of block = 24 inch x 9 inch (600 mm x 230 mm) = 0.138 sqm
Area of brick = 9 inch x 3 inch (230 mm x 70 mm) = 0.0161 sqm
Wall area = 3m x 3m = 9 sqm
Wall 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 Joints
Total Mortar Joints
85 rmt (approx)
170 rmt for 4-inch wall & 240-250 rmt for 9-inch wall
Weight
Weight
Weight of an AAC block (9 inch) = 16-17 kg
Weight of brick = 3-3.5 kg (approx)
1 no. 9 inch block = 14-15 bricks
Bricks 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 Speed
AAC Blocks
Bricks
Dimensional Accuracy
AAC 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 Joints
AAC blocks have fewer joints, increasing construction speed.
Red bricks have 4 times more joints than AAC blocks, significantly reducing construction speed.
Coverage Area
AAC blocks cover a larger area.
Bricks cover a smaller area.
Skill Requirement
AAC 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 Joints
AAC 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 Labor
AAC Blocks
Bricks
Pre-curing and post-curing labor
AAC 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 Mixing
AAC Blocks
Bricks
Mixing Process
AAC 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 Cost
This can save substantial labour costs incurred for mortar mixing and conveying.
Extra labour costs involved for mortar mixing and conveying.
AAC BLOCKS VS RED BRICKS – MORTAR MIXING
Conveying and re-handling labour
Conveying and Re-handling Labour
AAC Blocks
Bricks
Supply and Conveying
AAC 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 Wastage
Saves 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
Description
Quantity
x
Rate (INR)
=
Cost (INR)
1 CUM Brickwork = 0.35 to 0.4 CUM mortar
Sand cost (Rs. 2500/- per CUM)
0.35
x
2500
=
875
Cement
1.3
x
300
=
390
Total cost per CUM of brickwork
INR
1265/-
Analysis of Block Adhesive
Description
Details
1 CUM block work
30 kg of block adhesive
Rate per kg
Rs. 12-15 per kg
Cost for 30 kg
Around 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.
The advantages of AAC blocks over other alternatives stamps it as a perfect and superior building material in comparison with conventional bricks. Advantages of AAC blocks and their properties are listed out in detail.
Advantages of AAC blocks
AAC Blocks or Autoclaved Aerated Concrete Blocks are lightweight, load-bearing, durable, and economical walling material. They are eco-sensitive and green option to bricks, due to its enormous potentials in terms of insulation, fire-resistant, acoustic, and thermal resistant properties. AAC Blocks are superior material when compared with concrete, wood, brick, and stone. They can enhance the construction speed, reduce the costs, and minimise wastage at construction sites.
The unique qualities of AAC blocks are mainly due to its properties. AAC blocks are something more than a brick alternative. AAC block posses a lot of qualities that make them stand out from other alternatives. The advantages in terms of technical properties are listed below.
AAC blocks sizes are customised and manufactured in various sizes. The most common dimensions available in the market is : 600/625 mm (length) x 230/240 mm(height) x 100 mm-300 mm (thick)
TECHNICAL ADVANTAGES OF AAC BLOCKS
Dimension and appearance
The biggest advantages of AAC blocks are its Dimension and appearance.
AAC Blocks are factory manufactured and hence got a perfect size and finish with a dimension tolerance of +/- 5mm. They have sharp edges and corners, uniform colour, and pleasing appearance.
AAC block density is around (550-650)kg/cm3 which can be customised as per requirement.
AAC blocks pose a drying shrinkage of around 0.4 % which is considered very less when compared to conventional bricks.
Dimension optimisation is the main feature of AAC blocks. They can be customised to cater to any dimension requirements. AAC blocks are available in thickness ranging from 100 mm to 300 mm with a standard length of 600 mm/625 mm. The dimensions of AAC blocks also differ with the manufacturer.
Fire resistant advantages of AAC blocks
AAC blocks are non-combustible and got excellent fire-resistant properties. The melting point of the AAC blocks is around 1600 degrees Celsius which is much higher than the temperature of building fires, where it is around 500 degrees Celsius. AAC block can withstand fire up to 4-6 hours depending on the block thickness.
ADVANTAGES OF AAC BLOCKS DURING FIRE
Acoustic/Sound proof qualities
AAC Blocks possess low density and high porosity due to the presence of billions of voids. The voids make up 80% of the total volume. The AAC block got high sound absorption properties when compared with any other building materials like concrete and brick due to its high porosity.
The high acoustic properties make AAC blocks a preferred choice for cinema halls and auditoriums walls.
Insect and termite resistant
AAC Block uses inorganic materials like fly ash, cement, gypsum, etc as ingredients in its manufacturing process. AAC block possesses good insect and termite resistant qualities due to the presence of these inorganic materials.
Advantage of AAC blocks – Thermal insulation and energy savings
Fly ash is the main ingredient and constitutes more than 70% weight of AAC blocks ingredients. The micro pores constitutes around 80% of AAC blocks accounts for its excellent thermal insulation properties. The thermal insulation qualities help in maintaining inner temperature cool in summers and warm in winters. More cooler interior means less AC load which in turn can reduce energy consumption by 20% and can eliminate costly thermal insulation.
Advantage of AAC block-Impact of earthquake
AAC blocks are lightweight and reduces dead load/ mass on the structure. The impact of earthquake is directly proportional to the weight of structure. Because of its light weight properties, AAC blocks can reduce the impact of earthquake to an extend and hence preferred for earthquake zones.
Water and Moisture Resistant
AAC blocks constitutes millions of micro pores which prevent capillary transport of water and moisture over a long distance. The walls can resist moisture even with a lesser thickness compared to bricks. The water and moisture resistant qualities enable to use a less thick block as partitions.
Advantage of AAC block in terms of strength
AAC blocks are highly superior in terms of the strength. Higher level of strength of these blocks gives higher stability to the structure of the building.
Economical compared to any other alternative
AAC blocks are economical and stands out as the preferred option due to a lot of factors. This is the main advantage of AAC block over conventional red bricks.
CUTTING OF AAC BLOCK
Ease of cutting and chasing
Using recommended tools we can easily cut,drill and chase AAC blocks . The blocks will not break,crack or de-bond from its position while doing so.
Ensure fast construction
AAC blocks are lightweight, easy to fix and have a very accurate dimensional tolerance +/-5 mm and can be fixed, jointed and plumbed easily.
A single block of any thickness have an area of 24 inches x 8 inches
For completing a wall of 10 ft x 10ft
Surface area of block = 24 inch x 8 inch = 0.6 m x 0.2m = 0.12 sqm per block
Area of wall : 10 ft x 10 ft = 100 sq ft = 9.29 sqm
Quantity of block for an area of 9.29 sqm
9.29 sqm/0.12 sqm = 77.41 blocks for 100 sqft
Ordinary brick area is 9 inch x 3 inch = 0.23 m x .075 = .01725 sqm
Area of wall = 9.29 sqm area = 9.29/.1725 =
538 bricks (for 4 inch thick wall) and 1080 bricks for a 9 inch wall)
Higher the number of bricks greater the number of mortar joints.
AAC blocks are big in size and it can cover 13-14 bricks with a block. This can speed up the construction.
Advantage of AAC block in terms of Labour cost
PLACING OF AAC BLOCK
AAC blocks are very fast and easy to place due to the less number of joints when compared with bricks.
AAC blocks doesn’t require any soaking before placing for masonry and no curing is required after carrying out the works. The block adhesive used is air cured . This can reduce substantial labour and infrastructure costs involved in curing and soaking of blocks.
AAC block uses ready mix block adhesive in place of mortar for bonding the blocks, wherein mortar making requires handling of aggregates, mixing and conveying to the location for use. The labour involved in this lengthy process can be saved in the case of AAC blocks. More over the area looks neat and clean as site mixed mortars tends to generate a lot of waste.
Bricks got 4 times more mortar joints than AAC blocks. The dimensional tolerance of bricks are very high around +/- 5 mm to 15 mm and more. It is difficult to plumb and place in position.
AAC block work can even be done with a semiskilled labour with a little bit of training mostly due to their dimensional accuracy.
AAC blocks are available in pallets and can be conveyed and lifted to any location with the help of cranes and tower cranes. This can save labour involvement in carrying of blocks.
Because of these factors the labour charges for placing AAC blocks are almost 50% less when compared with conventional bricks/ or any other walling material.
Advantages of AAC block – Savings in material cost
Saving in jointing mortar
The block adhesive joint thickness is around 3-4 mm and it is much cheaper than mortar which includes cement and sand and its mixing.
Saving in plastering material
There is a huge amount of savings in terms of plastering. AAC blockwork presents a fair face on both sides of wall whereas brick work generates a fair face and unfair face on the walls. For covering the unfair face of brickwork the thickness of mortar should be adjusted to a minimum of 18 mm or more. In case of AAC blocks due to its dimensional accuracy they can be covered even with 10 mm thick mortar on inside faces and 12 mm thick mortar for outside faces. AAC blocks comes in perfect shapes and can even be painted directly after applying POP or gypsum plaster in very thin coats.
PLASTERING OF AAC BLOCKS
Wastages
AAC block wastage is around 2% whereas brick wastage is around 10% to 15% which is relatively very high. This can generates substantial saving in terms of wastage and removal of debris.
Design optimisation
AAC blocks are light weight with very less density of around 600 kg/cm3. Structural designers can optimise their designs due to less dead loads similarly optimised design consume less steel and concrete.
AAC is 100% Green building material & is a walling material of a choice in LEED certified buildings. AAC is most energy & resource efficient in the sense that it uses least amount of energy in manufacturing and material per cum of product. Brick manufacturing process uses fertile topsoil wherein AAC uses Fly-ash (65% of its weight) which is an industrial waste harming the environments.
AAC Blocks is a unique and excellent building material due to its superior heat, fire and sound resistance qualities. AAC blocks are lightweight and offers ultimate workability, flexibility and durability.
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