Autoclaved aerated concrete is an unusual building material with properties that should make it a hit in residential construction — it’s a much better thermal insulator than ordinary concrete, while lightweight, easy to work with and resistant to fire, insects and mold. The only problem is that Indian builders can’t seem to warm up to it. Some residential builders who specialize in energy-efficient designs have tried using AAC, but most have since left the fold.
AAC has a lot in common with ordinary concrete, with a few notable exceptions. Instead of fine and coarse aggregate, AAC uses sand or fly ash plus aluminum powder to create millions of tiny bubbles in the mix. The mixture is placed in molds and cured in an autoclave, which uses steam and pressure to complete the chemical transformation.
AAC blocks, like conventional concrete masonry units, are laid up with mortar. Blocks are placed over lengths of steel rebar that are cast into the foundation walls, and these holes are later filled with grout. Blocks can be cut with the same tools used for wood — bandsaws are commonly used to cut blocks to size.