Feasibility study of utilizing Autoclaved Aerated Concrete (AAC) waste for the production of cold bonded lightweight artificial aggregate using high volume fly ash (HVFA) binders

Autoclaved Aerated Concrete (AAC) is a popular construction material used for partitions and insulation in buildings. At the end of its service life, AAC (Autoclaved Aerated Concrete) will be demolished and subsequently disposed of in landfills, thereby creating depository problem. Therefore, the study of reutilization and recycling of AAC waste is imperative. Artificial aggregate production can be an alternative to the reutilization of AAC waste. This paper assesses the feasibility of using Autoclaved Aerated Concrete Powder (AACP) waste as a raw material for the production of artificial aggregate and investigate its physico-mechanical properties. The investigation incorporates the comparison of cement-based binder with high-volume fly ash (HVFA) binder with different replacement levels of cement. The study uses image analysis based on photographic, optical microscopic, and scanning electron microscopy (SEM) images, to describe the porosity of the aggregate. The results show that the AACP aggregates with both cement and HVFA binders meets the current industry requirement for density and cylinder crushing strength as lightweight artificial aggregate. The appropriate binder content lies between 30 % and 40 %. The best cement to fly ash ratio in HVFA binder is determined to be of 1:1 with 50 % replacement of cement with fly ash. Image analysis showed that the porosity largely affected the properties of the AACP aggregate such as density and water absorption. However, further investigation into the reducing high-water absorption of AACP aggregates is necessary to improve their overall quality.