Former Dean (Civil Engineering)
Anna University and
Former Emeritus Professor, IIT Madras.
Autoclaved Aerated Concrete Block is a viable replacement for conventional red clay bricks, which we normally use for our building construction. Red clay bricks are used for load bearing as well as for filler walls of RCC frames in high rise structures. There is considerable difficulty, of late in getting good quality bricks. In addition manufacture of bricks cause depletion of top soil and is considered environmentally unfriendly. Therefore we have recently looked for viable alternatives.
The alternative that we propose should be durable and have properties similar or Better than conventional bricks. The Autoclaved Aerated Concrete (AAC) block is a very timely introduction to the building industry, which fulfils the need for walls in buildings.
For a good product, it should be quality assured as per BIS standards. In case of AAC Block, IS code 2185: Part III: 1984, defines all the quality parameters. The adoption of AAC block in building construction will lead to the following advantages,
- It reduces the load on the foundation and other structural components in a structure due to its self weight of 600 to 800 kg/cum, as compared with the self weight of brick masonry of 1900-2000 kg/cum.
- Because of reduction in self weight, AAC block construction attracts, Less earthquake load.
- The output of the mason will increase because of less number of joints.
- The AAC block is thermally better and hence when adopted leads to less energy for air-conditioning
- The AAC Block has better sound insulation properties, Due to its air voids presence
- The AAC block is dimensionally more accurate as it is produced with wire cut technology in a certified factory.
- The normal brick wall has considerably more joints, Due to small wall size of brick. On the other hand, Due to longer size, AAC block has less joints and Hence less mortar consumption.
- The AAC Block, When built has both faces as fair faces, Unlike brick work, Which has only one face as a fair face? Hence if plastered, The thickness of Plaster for AAC block is much less compared to conventional bricks.
- The AAC block is light, Has air voids and hence has better fire resisting property compared to red clay bricks.
- The product being produced in a factory, Has uniform quality and hence is more durable.
- The raw materials used for the production, Has been found to be eco – friendly, As very little cement is used. The use of fly ash in this venture, Makes us to Utilize a waste material from thermal plants.
- The red clay bricks now available in many parts of India are Classified as Class A, class B and Class C bricks. The bricks available in South India are of
much poor quality because of the type of clay available here. Therefore we are able to produce only Class C bricks, which accounts for a strength of about 30 to 40 kg/sqcm. This strength range of 35 to 40 kg/sqcm, and Hence is much better then undependable red bricks strength.
Based on all the above, I have no hesitation in recommending the use of AAC Blocks For building construction in the following areas of work, where usually red clay bricks are Now being used.
- All Filling areas including in flat slabs and instead of brick bats in weathering course, over roof.
- Partition walls in Load Bearing and Framed Structures.
- Infill walls in Multistory Building Frames both internal and external walls.
- Load Bearing masonry upto 2 to 3 storeyes.
By proper design, The use of Autoclaved Aerated Concrete ( AAC ) Block, Will result in economy on overall cost.