IS 11239 covers autoclaved aerated concrete (AAC) blocks and panels. AAC is a lightweight, insulating building material with density 450-1000 kg/m³ (vs normal concrete 2400). Increasingly popular in India for non-load-bearing walls due to lower weight, better insulation, and faster construction.
Specification for precast cellular (aerated) concrete products including blocks and panels, covering classification, properties, dimensions, and testing.
Key Values
Grade 1 density451-550 kg/m³
Grade 1 min strength1.5 MPa
Grade 2 density551-650 kg/m³
Practical Notes
! AAC blocks are 3-4 times lighter than clay bricks — significant reduction in structural dead load and foundation cost.
! Grade 2 (density 550-650) is the most commonly used grade for wall construction in India.
! AAC has excellent thermal insulation (0.16 W/mK vs 0.81 for clay brick) — reduces cooling costs by 25-30%.
! Use polymer-modified thin-bed mortar (3mm) not conventional cement mortar (12mm) for AAC joints.