Structural Lightweight Concrete Containing Recycled Lightweight Concrete Aggregate

In this paper, Structural Lightweight Concrete (SLC) containing Recycled Lightweight Aggregate (RLA) is described. Damaged lightweight concrete was used as RLA by crushing it into fine particles, and used to replace fine limestone aggregate of up to 45% by weight. To enhance the strength development of SLC, silica fume and a superplasticizer were incorporated into the mixture. The compressive strength, density, water absorption, porosity, modulus of elasticity, and thermal conductivity of the concrete were tested. The results show that SLC with satisfactory 28-day compressive strengths of between 16.5 and 30.5 MPa, and densities of between 1600 and 1800 kg/m3, were obtained. The compressive strength, modulus of elasticity, and thermal conductivity decreased with an increase in RLA content, and the water absorption and porosity increased. Water absorption of 3.28–7.87%, porosity of 6.82–13.87%, modulus of elasticity of 16.5–25.2 GPa, and thermal conductivity of 0.49–0.75 W/mK were found to be within the working range of SLC.