AAC (Aerated Autoclaved Cellular lightweight) Blocks are approximately 3 times lighter than conventional bricks/blocks. Size is 16 times larger compared to conventional bricks and about 2 times larger than cement blocks. AAC has several superior properties and wider applications compared to conventional bricks/blocks. AAC is also highly cost effective.

History & Process

AAC was developed and perfected in Sweden during 1920-1930. It is being produced since the last 80 years in Europe and other developed countries and subsequently in China and the Middle East countries. In India also, it is gradually replacing conventional bricks due to several advantages.

The main raw materials are approximately 70% pulverized silica sand or pulverized coal ash, 15-20% quick lime, 10-15% cement and gypsum and about 0.5% aluminum powder. In India, the most common used material is pulverized coal ash or fly ash from thermal power stations

The raw materials are precisely proportioned with modern weigh feeding systems and made into a slurry with water. The slurry is poured into moulds where the expansion agent reacts with the lime and cement to produce millions of Hydrogen gas bubbles. The Hydrogen bubbles try to escape through the slurry and in the process facilitate the slurry to expand and rise to about 2 to 2 ½ times its initial volume. The cake sets and hardens into a stable cell matrix which is then trimmed and cut precisely into blocks. The cake is then steam cured in a pressurized autoclave for about 12 hours where it undergoes a second chemical reaction to form Calcium Silicate.

Special features of Production line

  • The entire process is under automation with modern process control systems thus ensuring high consistency and superior quality blocks
  • The proportioning of raw materials is carried out using most modern weigh feeding systems to ensure consistently superior quality blocks
  • Round the clock quality control checks during production
  • Usage of raw materials after testing their suitability for producing superior quality blocks

Properties & comparison with conventional bricks

1 Density 650 kg/m3 or 0.65 1.5 – 2.5
2 Compressive strength 3 – 6 MPa comparable to or higher than conventional bricks 3-5 MPa
3 Fire resistance 4-6 hours 2-4 hours
4 Thermal conductivity 0.122 0.4-0.6
5 Sound Reduction 60 dB 40 db
6 Variation in dimension +/- 1 mm +/- 3 mm

Advantages of AAC bricks

  • Less cement consumption in mortar for jointing bricks due to large size of each block
  • Less cement consumption in mortar for plastering and less putty/POP due to precise edges/shapes as the bricks are made in factory with high level automation
  • Less cement/concrete consumption in foundations/pillars/beams due to less load in structure/slabs due to light weight of blocks
  • Savings in transport and handling costs due to light weight
  • Reduction in construction time
  • Savings in labor cost
  • Savings in electricity consumption for AC’s due to better insulation
  • Better earth quake resistance due to light weight and porous structure
  • Increase in carpet area due to optimum thickness of wall
  • Better acoustic insulation due to superior sound absorption properties resulting in reduced noise pollution
  • Superior termite/pest/fungus resistance
  • Construction flexibility – easy to install with precision, can be sewn, drilled, nailed, grooved, etc., on site by Masons using simple working tools.

Available sizes

600 mm x 230 mm x 200 mm (24 in x 9 in x 8 in)

600 mm x 200 mm x 200 mm (24 in x 8 in x 8 in)

600 mm x 150 mm x 200 mm (24 in x 6 in x 8 in)

600 mm x 125 mm x 200 mm (24 in x 5 in x 8 in)

600 mm x 100 mm x 200 mm (24 in x 4 in x 8 in)