Brick and glass waste valorisation in the manufacture of aerated autoclaved concrete

Abstract

Autoclaved aerated concrete (AAC) is a light building material with high porosity, used to improve thermal and sound insulation of the buildings. AAC have a much better thermal efficiency than traditional masonry materials (bricks) or reinforced concrete elements; its use reduces the energy consumption (up to 7%) and consequently the carbon footprint of construction sector. The main constituents of autoclaved aerated concretes are portland cement, siliceous material (aggregate), water and different types of admixtures and additives (lime, foaming agent etc.). The aim of the research presented in this paper is to reduce the environmental impact of the technological process of ACC manufacturing; in this respect, one of the main components of AAC i.e. sand (natural raw material) was substituted with two types of inorganic waste i.e. glass (cullet) and waste brick; the sand substitution rate was comprised between 12.5-100% wt. The results indicate that both glass and brick waste can be incorporated into the autoclaved aerated concrete (AAC) structure without major modifications of apparent density (maximum 10% increase in correlation with substitution amount). For similar values of the apparent density, the AACs prepared with glass waste have higher values of compressive strength and thermal conductivity as compared with AAC with brick waste.