Mechanical properties, durability, and life-cycle assessment of concrete building blocks incorporating recycled concrete aggregates

This paper aims to explore the possible use of recycled concrete aggregates (RCAs) to produce concrete building blocks. Laboratory test and plant trial were carried out to manufacture concrete building blocks incorporating 75% RCAs. A series of tests were conducted to investigate the mechanical and durability properties of the recycled aggregate concrete (RAC) blocks. The compression and shear performances of masonry prisms built with RAC blocks and conventional mortars were experimentally studied too. Furthermore, the environmental impact of RAC blocks was studied using life-cycle assessment (LCA) method. Five different environmental impact categories (i.e., GWP, AP, EP, HTP, POCP) are calculated and comparatively analyzed. The effect of RCAs on the mechanical and durability properties, as well as the environmental impact of RAC blocks was investigated. The test results indicate that the incorporation of RCAs slightly declined the compressive strength and impaired the durability of the concrete blocks. Nevertheless, concrete building blocks incorporating 75% RCAs satisfied the strength, drying shrinkage and freeze-thaw resistance requirements for concrete building blocks specified by Chinese standard. The compressive and shear performances of masonry prisms constructed with RAC blocks are similar to those of conventional concrete masonry. RAC blocks have less environmental impact compared to normal concrete blocks. It is feasible to use RCAs to manufacture concrete building blocks along with environmental benefits. The use of RAC blocks plays a key role in ending the building life cycle and will improve the sustainable development of masonry structures.