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Lightweight Building Blocks

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Autoclaved aerated concrete (AAC) block is a versatile lightweight construction material with low density and excellent insulation properties. P Venkatesan, Managing Director, Methra Industries India Pvt. Ltd which manufactures of Cell O Con AAC blocks briefs on the product characteristics.

The autoclaved aerated concrete blocks density ranges from 460 to 750 kg m-3 in comparison to medium density concrete blocks density range of 1350-1500kgm-3 and dense concrete blocks density range of 2300-2500kgm-3. This low density is achieved by the formation of air voids producing a cellular structure. The voids are typically 1mm – 5mm across and also give the material its characteristic appearance.

Furthermore, the AAC porous character offers excellent thermal and sound insulation properties, because of which these blocks are widely used to form the inner leaf of a cavity wall. They are also used on the outer walls and in foundations as they provide good resistance to sulfate attack, fire and frost. The blocks have strengths ranging from 3-9Nmm-2 (when tested in accordance with BS EN 771-1:2000).

Production: In the slurry containing lime, cement, gypsum and fly ash, aluminum is added. The mould gets aerated due to the formation of hydrogen gas and the gas bubbles give the material a cellular structure. The moulds are wire-cut to required sizes and then loaded into the autoclaves measuring 45m in length and 3m in diameter. Steam is fed into the autoclave at high pressure i.e. 800kPa at a temperature of 180oC. The AAC blocks are cured in the autoclave for more than 8 to 10 hours to achieve high strength.

Likewise, the Cell O Con blocks are manufactured with latest technology aeration process and standard mix procedure through SCADA control. The process further includes procuring technology, tilting tables and 4.8 meters cutting machine. The autoclaving of Cell O Con by maintaining uniform stream pressure and temperature and its three-tier horizontal staking provides strength, quality and uniformity to the product. The tests conducted on the Cell O Con AAC blocks by the Structural Engineering Research Centre, CSIR Chennai and M/S Hitech Lab conforms to IS 2185.

The Cell O Con autoclaved aerated concrete blocks are eco-friendly, heat resistant and light weight blocks, best suited for high rise buildings. Their compressive strength is 3-9Nmm2 (when tested in accordance with BS EN 771-1:200). They reduce the dead load, offer more carpet area and require minimum plastering. Moreover, the blocks are energy efficient, resistant to insects & pests and minimize energy usage in building construction.


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