What is an AAC Block? | Are AAC blocks good or bad | is AAC block better than bricks | what are disadvantages of aac blocks | is plastering required for aac blocks | does aac blocks absorb water | AAC Block advantages and disadvantages.
Hi guys in this article we know about AAC Block benefits, AAC Block advantages and AAC Block disadvantages. Today in construction industry use of AAC Block replace the traditional red brick.
Today AAC Block is demanding building material for construction of wall due to its lightweight throughout the world in United States, United Kingdom, European countries, India South Africa, Singapore, Australia Canada and others many countries. These countries are larger consumer of AAC Block, they preferred to use of AAC block over traditional clay brick.
What is an AAC Block?
AAC block is autoclaved Aerated concrete which is lightweight, eco friendly, load bearing, high insulating, all weather certified green building material that are designed to offer superior performance and durability.
They are 8 to 9 times the size of a traditional red clay brick and provide better compressive strength and it is 3 times lighter when compared to Red clay bricks.
AAC Block was developed in 1920 by Swedish architect who was looking for alternate option of building material with properties similar to that of wood – which is good thermal insulation, solid structure and easy to work without disadvantages of combustibility, decay and termite damage.
What is full form of AAC Block?
Full form of AAC block is autoclaved aerated concrete (AAC), which is also known as Autoclaved Cellular Concrete (ACC) and Autoclaved Lightweight Concrete (ALC). It is building material invented in the mid-1920s that simultaneously provides sound proof structure, insulation, and fire and mould resistance.
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Raw materials of AAC Blocks
AAC blocks is composed of different raw materials or ingredients such as quartz sand, calcined gypsum, lime, cement, water and aluminum powder. Mixture of these materials produce AAC blocks which is a lightweight, precast, foam concrete building material suitable for producing concrete masonry unit (CMU) like blocks.
Is AAC blocks environment friendly?
One may ask, “is AAC blocks environment friendly?”, yes autoclaved aerated concrete (AAC blocks) is an eco- friendly and certified green building material which is lightweight, load-bearing, high- insulating & all weather construction material that are designed to offer superior performance strength and higher durability.
What is meaning of AAC Blocks?
Meaning of AAC block is that products which are cured under heat and pressure in an autoclave and there is presence of air in the mixture of ACC block and can offer hard bearing good compressive strength such as concrete that why it name is AAC block or autoclaved aerated concrete.
Is AAC Blocks thermal insulating?
Sombody ask, is AAC blocks thermal insulating?”, yes AAC block is a highly thermal insulating concrete based material used for both internal and external construction and are Light weight, energy efficient, fire and sound proof, easy to install, handling and environmentally certified green concrete product as it is also Ecological and Recyclable product.
Higher strength to weight ratio, seismic resistance, precision, breakages next, light weight properties of AAC block makes it ideal for construction of internal and external wall in the house.
AAC Blocks are unique and excellent type of building materials offers ultimate good workability, flexibility and durability. AAC has excellent thermal insulation and acoustic absorption properties. It is fire and pest proof resistant, and is economically and environmentally superior to the more traditional structural building materials such as concrete, wood, brick and stone.
AAC Blocks in the name of concrete are manufactured using the finest grade (Class F) fly ash, gypsum based and other raw materials.
Is AAC blocks better than bricks?
One may ask, “is AAC blocks better than bricks?”, yes, AAC blocks have some advantage over brick when compared, it is eco friendly certified green building material which is lightweight, higher strength, uniform shape and size, easy to installation and it also reduce construction cost whereas brick manufacturer process is not eco friendly it release harmful gases in our environment, thus causing pollution.
Are AAC blocks good or bad?
Someone ask, “are AAC blocks good or bad?”, yes it is good incase of light weight, energy efficient, fire and sound proof, easy to install, handling and environmentally certified green concrete product which even reduces the construction cost.
Is plastering required for AAC Block wall?
Regarding this, “is plastering required for AAC Block wall?”, AAC Block is easy to install and work, due to uninform shape and size and perfect placing of AAC Block during the wall formation resulting smoother and good finish that not need to be plastering, if plastering install on block wall that need to be thin layer of plaster incase of cracking and uneven placing because AAC block installation in wall need to be high skill labour quality.
Does AAC blocks absorb water?
In this regard, “does AAC blocks absorb water?”, yes, dry AAC blocks absorb water content in mortar and retard the hydration process between cement and water.
AAC blocks specification
AC Block have dimension of regular size of 600mm in length by 200mm height and their width range between 75mm to 300mm and of compressive strength of 7.5 to 10 MPa, density range between 550 – 650 kg/m3, fire resistance 2 to 6 hrs depending on thickness, drying shrinkage of 0.04% and sound reduction index of 45 DB for 200mm thick wall. This is specification of AAC Block.
Why AAC Blocks get cracks?
All concrete blocks are prone to cracks due to installation defects, it can be minimise by taking certains precautions, some of the reason behind such cracking is deflection of beam, uneven placing of AAC blocks, a structural movement caused due to thermal expansion or change in moisture content. One way to avoid this to deley the use of block till equilibrium moisture content is reached.
Standard size of AAC Block
Standard size of AAC Block is 600mm in length by 200 mm in height and their thickness vary from 75 mm to 300mm, most regular used nominal size are 600mm × 200mm × 100mm (24″ × 8″ × 4″) for 4″ thick wall & 600mm × 200mm × 200mm (24″ × 8″ × 8″) used for 8″ block wall. This is a standard size of AAC Block.
AAC block weight
Weight of AAC Block depending on their size, density and composition of of raw material, generally it will be vary from 6 to 20kg, for 3″ thick AAC block weighs around 6 to 7kg, 4″ thick weighs about 8 to 9kg, 5″ thick weighs about 10 to 11kg, 6″ thick weighs about 12 to 13kg, 7″ thick weighs about 14 to 15kg, 8″ thick weighs about 16 to 17kg, 9″ thick weighs about 18 to 19kg & 10″ thick aac block weighs about 20 to 21kg.
AAC block Advantages & properties
Let us now discuss about AAC Block advantages, benefits and their different properties and uses.
◆ 1) AAC Block Autoclaved aerated concrete.
◆ 2) it is lightweight,precast, foam concrete building material suitable for concrete masonry unit.
◆ 3) it is eco friendly in nature not producing pollution in environment and it is certified green building material.
◆ 4) it is load bearing in nature having high compressive strength 5N/mm2
◆ 5) it is also fireproof insaluting building material having a resistance of about 4 an hour against fire.
◆ 6) actually it is aerated concrete have more air voids, due to presence of air void in between that’s why it is lightweight and easy for handling even it has high volume.
◆ 7) there are different size of AAC Block are available in market, but there are four common size are 600mm × 200mm × 100mm,600mm × 200mm × 150mm,600mm × 200mm × 200mm and 600mm × 200mm × 225mm.
◆ 8) water absorbing capacity of AAC Block are about 10% of their weight
◆ 9) there are three class of AAC Block, dry density of first class AAC blocks are 651 – 750 kg/m3, 2nd class dry density is 751 – 850 Kg/m3 and 3rd class dry density is 851 – 1000 Kg/m3. And wet density of 1st class is about 700 -800 Kg/m3.
◆ 10) It is composed of quartz sand, calcined gypsum, lime, cement, water and aluminum powder.
◆ 11) AAC blocks provide greater insulation against sound out loud noises and providing good insulation.
◆ 12) AAC Block are light weight and durable and can withstand extreme earthquake condition.
◆ 13) AAC blocks are easier to use in the construction process and save time as well as money for contractor and owner like. Due to presence of air in mixture AAC blocks and light, yet strong due to the process through which they are created.
◆ 14) AAC blocks made in uniformly and can be cut and shaped according to required in construction. it provide greater insulation against heat since they do are not good conductor of heat. The technology used in creating AAC blocks ensure that is blocks are resistant to fire.
◆ 15) More carpet area is available in built up area due to lesser widths of walling and cladding with 100/150 or 200mm against in case of conventional brick masonry.
◆ 16) Fast returns on investment due to speedy construction, saving in Cement, Steel construction supervision cost, construction time, water requirements for construction, timber required for centering /shuttering etc.
◆ 17) Uniform quality due to mass production in the factory. Due to high insulation properties of Autoclaved Aerated Concrete, there will be substantial saving in installation and recurring cost of air conditioning units.
◆ 18) AAC Blocks are wire cut & are having plain surface. In view of this, the Plaster for internal walls is not required & directly Putty & Painting can be done, saving the plastering cost. However, External Plastering is recommended for AAC Blocks.
◆ 19) Due to Light Weight and Earthquake resistant also comfortably worked and highly insulating and less water penetration and environmental friendlily also fire resistant and incombustible.
AAC block disadvantages
Disadvantages of AAC Blocks are following:– AAC blocks have brittle nature; therefore, they require more care than clay red brick during handling and transporting. The cost per unit of AAC block is high, but overall, masonry cost is low because it requires less cement mortar for installation.
“What are the disadvantages of AAC blocks?”, AAC blocks are formed by pouring foam concrete into a mould then setting them until the desired strength is attained. To understand AAC blocks one must understand the basics of foam concrete. It is formed by adding a foam (something similar to the shaving foam we use) to a cement-flyash slurry.
Any synthetic foaming agent has a max stand time of 2 hours before the foam starts collapsing. Therefore the mix design should set within before 1.5 hours and harden sooner else the concrete will simply collapse. To entrain foam into the slurry the mixture should have a water content of atleast 50% else.
Some of the Main Disadvantages of AAC Blocks are given below:-
1) AAC Block is Non load Bearing material, it can be used only in wall partitions.
2) AAC block is brittle in nature that means It can break easily. Presence of voids makes it brittle in nature.
3) Their water absorption is very high. With this their expansion on absorbing water and contraction on loosing moisture bring cracks in structure.
4) If installed in high humidity environments, interior finishes require low vapor permeability and exterior finishes require high permeability.
5) Very few contractors who are familiar with AAC Block but now a days it is increasing day by day.
Let us now discuss AAC Block disadvantages, brittle nature, handling,fixing and installation drawbacks.
● 1) Brittle nature: it has some brittle nature ,they need to be handled more carefully than clay bricks to avoid breakages.
● 2) Fixings: the brittle nature of the blocks requires longer thinner screws when fitting cabinets and wall hangings and wood-suitable drill bits or hammering in.
● 3) Special, large diameter wall plugs are available, though at a higher cost than common wall plugs.
● 4) Insulation requirements would require very thick walls when using AAC alone. Thus many builders choose to return to traditional building methods installing an extra layer of insulation around the building.
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