Effect of perlite waste addition on the properties of autoclaved aerated concrete

• The EPW can be used as a quartz sand replacement in the production of AAC.
• The EPW has positive influence on the formation of calcium silicate hydrates.
• Replacing the quartz sand by EPW has a positive effect on the thermal conductivity of AAC.

In presented paper, the influence of expanded perlite waste on the properties of autoclaved aerated concrete (AAC) was investigated. Expanded perlite waste was used as a quartz sand replacement in conventional AAC mixtures at 5%, 10%, 20%, 30% and 40% by weight. Results show that use of expanded perlite waste in AAC caused a unit weight decrease in the produced AAC, it is connected with the changes in the properties of AAC. The thermal conductivity coefficient and compressive strength of specimens decreased as the amount of expanded perlite waste increased in AAC. The introduction of perlite waste up to 10% by weight reduced the thermal conductivity about 15% without significant reduction of compressive strength. Further improvement of thermal conductivity may be obtained by the addition of perlite waste up to 30%, but it caused reduction compressive strength about 20%. The minimum thermal conductivity value was 0.074 W/m·K, observed at 40% expanded perlite waste replacement. The structural and microstructural investigations showed that expanded perlite waste has a positive influence on the formation of calcium silicate hydrates (1.1 nm tobermorite) in AAC. From this result, it was concluded that expanded perlite waste can potentially be used as quartz sand replacement in the production of AAC.