An Innovative Autoclaved Aerated Concrete (AAC) with Recycled AAC Powder for Low Carbon Construction

Abstract

Recycling of materials, in particularly concrete was not frequently practiced in construction and moreover no study has been carried out yet. Furthermore, the environmental impact of recycling in construction was not known and no study has been carried out, thus now it leads to give an abundance of wasted concrete at site. Autoclaved aerated concrete (AAC) is one of the lightweight concretes that commonly used in construction. AAC is relatively light in weight, having lower thermal conductivity, higher heat resistance, lower shrinkage, and faster in construction process when compared to the conventional concretes. AAC consist of silica sand, cement, lime, water and expansion agent. To reduce the construction waste, an innovative AAC block has been developed by using recycled AAC in powder form to replace sands in the manufacturing process. The new developed AAC was conducted by replacing sand with recycled AAC in ratio of 0%, 15%, 20%, 25%, 30%, 45%, 40% and 45%. Microstructure analysis were conducted using optical microscopic and scanning electron microscopic (SEM) while the chemical analyses were conducted using X-ray diffraction (XRD). Mechanical tests such as density, compressive strength, flexural strength and water absorption also have been carried out. It could be observed that by replacing the sand content with recycled AAC, AAC with fine recycling powder content of 30% by weight has a compressive strength that is approximately 16.1% greater than conventional AAC and is between 30-110% higher than any value obtained by utilizing industrial waste product.