RECYCLING OF AAC WASTE IN THE MANUFACTURE OF AUTOCLAVED AERATED CONCRETE IN VIETNAM

Abstract

The use of recycled materials helps investors to save significantly on production costs, not only from raw material extraction cost but also in the production process. Especially, recycling waste materials helps reducing energy, fuel, and labor costs. Besides, the transportation of recycled materials is also less expensive than the transportation of raw materials. The workload involved in the recycling of materials is minimal but with economic and technical efficiency. Autoclaved aerated concrete (ACC - Autoclaved aerated concrete) has been widely applied in construction works in Vietnam and is considered a reasonable replacement of fired bricks due to lower volume density, and better soundproofing - insulation. The main materials used to make AAC concrete include ground quartz sand, cement, lime, gypsum, aluminum powder, and some other technological additives. However, due to the depletion of natural sand, the partial or complete replacement of natural sand in AAC concrete production plays an important signification. In this study, the AAC waste after the autoclaving process was reused to replace the ground natural sand. The research results show that the AAC waste bricks could be reused with a content of up to 25% to replace the natural sand in AAC fabrication. The main properties of products such as compressive strength, bulk volume density, and drying shrinkage meet the technical requirements of ASTM C1693.