Development of cement-based lightweight composites – Part 1: Mix design methodology and hardened properties

This article aims at the development of durable cement-based lightweight aggregate composites, with a good balance between the thermal and mechanical properties. The mixtures are developed with the optimized packing applying the modified Andreasen and Andersen model, to obtain the optimal target grading curve of all the solids in the mixture. A lightweight material produced from recycled glass is used as the lightweight aggregates (LWA) in order to obtain the desired low thermal conductivity. The properties of the designed composites, including the flowability and relative viscosity in fresh state, and the porosity, strength and thermal properties in hardened state are investigated. The porosity of the developed composites is studied by both modeling and experiments. Results indicate that there is a certain amount of closed internal LWA pores in the composites, which contributes positively to a better thermal insulation property. The developed composites have a low thermal conductivity while still retaining sufficient strength. Therefore, the designed composite can be used monolithically as both load-bearing element and thermal insulator.