Development of an environmental foamed concrete incorporating recycled cement concrete powder with carbonation

Abstract

From the perspective of efficient resource utilization and environmental protection, it is an effective way to reduce waste by carbonizing recycled cement concrete powder to replace part of cement. In this study, carbonated and non-carbonated recycled cement concrete powder were selected as supplementary cementitious materials to investigate the effects of different cement substitutes (0%, 20%, 40%, 60%) on the workability, microstructure, and thermal insulation performance of foamed concrete. The experimental results show that carbonation treatment can improve the workability of foamed concrete with waste cement concrete powder, with an amplitude ranging from 1.08% ∼ 5.61%. The influence of different carbonated powder substitution on the compressive strength of foamed concrete shows an initial increase followed by a decrease, with a range of variation from 2.27 MPa ∼ 4.47 MPa at 28 d, which is attributed to the effective acceleration of hydration due to a slight increase in the content of calcite. Mechanical strength is positively correlated with the density of the matrix, and the change of the two leads to an opposite trend in thermal insulation performance, with the maximum reduction in thermal conductivity being 9.98% at a substitution rate of 60%. These research findings indicate significant potential applications of waste cement concrete powder at various substitution rates, and are of great importance for achieving the dual-carbon strategy.