(1)(2) Doctoral Scholar, (3) Professor, Building Technology and Construction Management Division, Department of Civil Engineering, Indian Institute of Technology Madras, Chennai 600036, email:


The potential use of large volume fly ash and its suitability in improving the properties of autoclave aerated concrete (AAC) is considered important in the construction industry. This study was carried out to design an AAC mix with high volume fly ash and with low cement content to enhance the properties of AAC, which has application for use as masonry units. Binders such as 10%, 20% lime and 3, 5 and 10% gypsum were added and their effect on AAC properties studied, for a range of 0.1 to 0.25% aluminium powder and 0 to 0.075% superplasticizer dosages. Cement, fly ash, lime and gypsum were used in different combinations including as binary, ternary and quaternary mixes of AAC. Dry density, compressive strength, strength to density ratio and water absorption of AAC were examined. The Quaternary mix resulted in high strength and strength to density ratios compared to binary and ternary mixes of AAC with low cement content. The study exposes a range of strength to density combinations of AAC for application as masonry units.

KEYWORDS: autoclaved aerated concrete, lime, gypsum, fly ash.