In the world of the precast concrete, autoclaved aerated concrete or also known as AAC takes an important position. The precast concrete offers many benefits for users as it is easy to use, affordable, and also does not require extra knowledge during their construction. The AAC is manufactured in different forms and then are let to the markets, unlike the idea of pouring concrete at the site of construction.
Many companies offer top quality building materials to the world, and the one that is in great demand is Ecotrend Materials. This is a Chinese-invested enterprise and takes pride in standing at the topmost position in the list of the best quality autoclaved aerated concrete manufacturers. They use lime, fly ash or silica sand, cement, and aluminium paste for manufacturing these blocks. You can visit their website to know more.
The first usage of AAC dates back to the early 1920s when Swedish people used these blocks to construct many architectures with it. Just like a bread dough rises, the mixture of lime, cement, water, sand, and a minimal amount of aluminium powder can do the magic of baking these blocks and increasing their size to give them the perfect shape of concrete blocks.
Here is a brief explanation on how AAC is manufactured.
The materials used
The materials that are used during the manufacturing of AAC blocks include -
Cement: OPC grade 53 cement is the only option for manufacturing AAC because of its capacity to bind the materials together and also the hardening factor.
Fly Ash: This is used to reduce the overall cost of construction. With a density of 400 to 1800 kg/m cube, this material is best known for offering resistance against fire, thermal insulation, and sound absorption.
Limestone: This is obtained by either purchasing the powder from a merchant or by following the idea of powdering the rock to the desired form. It is done in the AAC factory.
Aluminium Powder: This is just like adding yeast to the bread-making dough. With enough supply of the powder, the raw material will start releasing hydrogen gas because of its interaction with water and calcium hydroxide.
Fly ash slurry is prepared by mixing water with fly ash. The idea here is to make it easier for the fly ash to combine perfectly with gypsum, cement, and aluminium powder in the required quantity.
This is the important step as it will decide the end product that is obtained after the whole procedure. The requirement in the strength and quality of the concrete blocks will decide the ratio of raw materials that should be used in the mixing and dosing process.
The sizes and shapes of the concrete blocks will be decided in this step. With the help of the right concrete block moulds, the required number of blocks are prepared. The moulds will be coated with a layer of oil to make sure that the blocks can be easily detached from them. The time duration required for the moulds to be set will be around 60 to 240 minutes based on the dimension of the autoclaved aerated concrete blocks.
The moulds will achieve the strength to withstand the cutting into desired dimensions. The available sizes of autoclaved aerated concrete blocks in the market are,
600 x 200 x 100
600 x 200 x 150
600 x 200 x 200
These autoclaved aerated concrete blocks are light weighted, durable, load-bearing capacitated, and also offer the best insulation to the buildings where they are installed. Hence, they are in greater demand for all kinds of construction than the red bricks.
Sustainable and Eco-friendly
The main reason for the usage of these autoclaved aerated concrete blocks is the presence of non-toxic ingredients. There will be no emission of poisonous substances to the environment and these are sustainable.
Design flexibility and easy workability
The best part of using these autoclaved aerated concrete blocks is that they can be cut into any shape and dimension.
Resistance to seismic activities
Studies have shown that the buildings or the architecture that are built using these blocks cannot be easily damaged from earthquakes or other such seismic activities up to certain levels in their scale. This factor makes them ideal for constructing fire-resistant buildings in some specific regions.
The buildings that are constructed using these AAC blocks are finished 20% faster than the architectures that are constructed using the other options such as red bricks. The lighter weight factor of these blocks makes them easier to transport from or to any locality.
Autoclaved aerated concrete is prepared by following a procedure where there is the addition of a type of foaming agent directly to the mould. These moulds are then wire-cut to bring them to the required shape and dimension. The obtained cake is then cooked or autoclaved to make them heat and fire-resistant.
The procedure of manufacturing is entirely different from that of the normal concrete, and hence AAC blocks will be comparatively light-weighted than the regular concrete blocks. The heat and fire-resistant qualities are absent in the normal concrete blocks, unlike AAC blocks.
Density – 20 to 50 pounds per cubic foot meaning that they can float on the water surface
Thermal resistance – 0.5 to 1.5 inches of thickness
Compressive strength – 300 to 900 psi
Sound transmission – 45 for a block of 8 inches
Shear stress allowance – 8 to 22 psi
Drawbacks of using autoclaved aerated concrete blocks
The registered drawbacks of using AAC blocks are,
No options in colour consistency
The requirement of exterior and interior porousness varies according to the area of installation
Comparatively costlier than the construction that include wood-frame and regular concrete block construction
For environmental benefit purpose, AAC is an ideal choice. This is the best choice for constructing homes or buildings for such people that have sensitive lungs for some chemicals. The growing demand has made AAC become the most preferred construction material today in many places around the globe.