Influence of silica fume addition on enhancing the autoclaved aerated concrete properties

The demand for lightweight concrete has increased because of its low density, fire resistance and good thermal insulation. Autoclaved aerated concrete (AAC) is the combination of cement, fine-grained sand, lime and water with aluminium powder. This study aims to investigate the influence of adding silica fume (SF) on improving the properties of AAC. The response was studied in terms of testing the mechanical and physical properties including compressive, splitting tensile, flexural strength, density, porosity and coefficient of water absorption. Different mixes have been proposed by incorporating the SF with contents of 10 %, 20 % and 30 % by cement weight, which is compared with the AAC sample that is used in practical applications. The results indicated that there was a significant improvement in the compressive and flexural strength of AAC, which increased by six and three times, respectively, when 30 % of SF was used with an acceptable dry density. Furthermore, the microstructural analysis revealed that SF had a positive effect on the development of calcium silicate hydrate and it can be used in AAC masonry block productions.