Effect of brick-based construction and demolition waste on the performance and microstructure of lightweight aggregate concrete

Brick-based construction and demolition waste (CDW) was successfully used to prepare lightweight aggregate concrete, and the effects of the CDW mineral admixture and aggregate on workability, hardened performance, microstructure and influence mechanism were also investigated. The results indicated that replacing lightweight aggregate from 0% to 100% with the CDW aggregate weakened workability and slightly depressed thermal insulation performance of concrete, but they could be improved by adding brick-based CDW mineral admixture. Higher strength of CDW aggregate compared with lightweight aggregate resulted in strength enhancement of concrete, and 20% of the CDW mixture increased 28-day compressive strength of concrete, due to pore refinement and pozzolanic effect of the CDW admixture. Lightweight aggregate concrete with a thermal conductivity of 0.63 W/(m & BULL;K),a dry density of 1935 kg/m3 and a compressive strength of 39.4 MPa at 28 days could be obtained, under the improvement of interfacial transition zone, pore refinement and high strength of aggregate.