AAC Blocks – Its 8 [ Technical specifications & Advantages ]

AAC blocks are precast, lightweight autoclaved aerated concrete and is a concrete building material which is used for producing concrete masonry units like blocks & under heat and pressure, AAC products are cured and composed of quartz sand, lime, water, cement, aluminum powder and calcined gypsum.

For both interior and exterior construction AAC products are used and to guard against the elements AAC products may be coated with plaster compound.

On sites using standard power tools with carbon steel cutters AAC material can be sanded, routed, or cut to size and it provides easy and quick installation of AAC blocks. For both interior and exterior construction They are highly thermal insulating and also AAC is well suited for buildings.

High rise buildings constructed using AAC due to its lower density and for structural members require less steel and concrete and due to dimensional accuracy of AAC products the material required for rendering is also lower and due to lower number of joints mortar is needed.

Due to its superheat, fire and sound resistance AAC blocks are unique and the best type of building material and AAC blocks offer ultimate workability, durability and flexibility and main ingredients are quicklime, cement, gypsum, sand, and water.

Manufacturing Process of AAC Blocks:

There are following steps in the manufacturing process of these blocks;

Raw Material Preparation:

With raw material preparation, its manufacturing process starts and there are following raw materials used in it such as;

Cement;

For manufacturing AAC blocks 53 grade Portland cement from manufacturer is required and to variations in quality over different batches of cement, cement supplied by plants is not recommended.

Sand or Fly Ash;

To form fly ash slurry fly ash or sand is mixed with the water and then with other ingredients like cement, lime powder,  gypsum and aluminum powder slurry is mixed.

Lime Stone Powder;

At AAC factories lime powder required for AAC production is acquired by crushing limestone to fine powder.

Gypsum;

In markets gypsum is readily available.

Dosing and Mixing:

Next step of manufacturing AAC blocks are dosing and mixing it means the quality of final products and the ratios for all ingredients are;

Fly ash or sand : lime : cement : gypsum is 69 : 30 : 8 : 3

The total dry material in the mix aluminum is about 0.08%.

To produce AAC blocks dosing and mixing unit is used to form the correct mix. Into a container fly ash is pumped and pumping is stopped when the desired weight id poured. Similarly all ingredients are poured in individual containers then all ingredients releases into the mixing drum. Using the dosing unit it is ready to be poured into molds and if there is a gap between charging and discharging of ingredients then the dosing and mixing process is carried out continuously.

Casting, Rising & Curing:

It is poured in molds once the mix of raw material is ready and depending upon installed capacity molds can be a various sizes. To ensure that green cake does not stick to molds, molds are coated with a thin layer of oil before casting. Aluminum reacts with calcium hydroxide and water and releases hydrogen gas while the slurry is mixed and poured into greased molds. Green cake is allowed to settle and cure when the rising process is over and the reason behind lightweight is that bubble size is about 2-5mm.

Demoulding and Cutting:

It is ready to demoulded and cut as per requirements once the green cake has achieved cutting strength and for demoulding operation it is lifted by a crane. Depending on technology provider demoulding and cutting processes vary vastly.  

Technical Specifications:

Advantages Of AAC Blocks:

There are following advantages of AAC blocks such as;

1. Reduces the heating and cooling load in the building, improves thermal efficiency.
2. In the AAC blocks Construction, Workability allows accurate cutting which minimizes the generation of solid waste.
3. In all phases of its cycle resource efficiency gives it a lower environmental impact.
4. Resistance to fire.
5. The AAC blocks are soundproof in nature due to porous nature.
6. Due to lighter weight the AAC blocks are resistant to earthquakes.
7. These blocks help in quick construction work.
8. Offering building extra life span the AAC blocks are long-lasting in nature.
9. In transportation lightweight of AAC blocks saves the cost and energy.
10. In autoclaved concrete, there are no toxic gases or other toxic substances.

Disadvantages Of AAC Blocks:

There are following disadvantages of AAC blocks such as;

1. Cracks in walls.
2. For load-bearing walls, not suitable perfectly.
3. You have to drill for any work in AAC blocks you cannot use nails.
4. Per unit AAC block production cost is higher.
5. Because of its smooth surface plaster sometimes does not stick properly.
6. Needs care during production.
7. Through mortar and water efflorescence occurs.
8. Skilled laborers are required.
9. Projects far from manufacturing facilities will suffer from higher initial cost because of long-distance.