Utilization potential of aerated concrete block powder and clay brick powder from C&D waste

This paper intends to study the recycled powder generated from aerated concrete blocks and sintered clay bricks. The powder was divided into different groups according to particle sizes with ranges of 0-0.045 mm, 0.045-0.075 mm and 0.075-0.15 mm. First, the energy consumption to prepare the powder with different particle sizes was calculated according to the grinding time. Various groups of powder were used to cast mortar samples with cement replacements of 10%, 20% and 30%. The slump and slump loss of the fresh mortar and the mechanical properties of the hardened mortar after 28 days of curing were investigated, as well as the shrinkage within 60 days. The results show that aerated concrete blocks are easier to crush than sintered clay bricks, but the energy consumption of grinding aerated concrete blocks into powder finer than 0.30 mm is higher than that of grinding sintered clay brick powder, which is verified by the energy consumption analysis. The mortar strength can be improved by replacing 10% cement with the recycled powder. The activities of three kinds of powder, from fine to coarse, obtained from aerated concrete blocks are 98.4%, 83.6% and 74.6%. For sintered clay brick powder, the activities are 73.7%, 87.9% and 85.8%. The aerated concrete block powder particles contain 2-3 mu m pores, which is the reason that it severely reduces the fluidity of the mortar, leading to considerably more shrinkage. (C) 2019 Elsevier Ltd. All rights reserved.