Recycled Brick as a Partial Cement Substitute

Abstract

The integration of construction demolition waste (CDW) as a supplementary cementitious material presents a promising avenue to mitigate the environmental impact of concrete production by reducing clinker content. Notably, in some areas, up to 50% of CDW are brick residues, highlighting the substantial potential impact of incorporating these wastes into construction practices. This study specifically focuses on optimizing cementitious mixtures by partially replacing ordinary Portland cement (OPC) with recycled brick powder (RB). Different mix designs, with RB replacement spanning from 10 to 90%, are analyzed through rheology (i.e., small amplitude oscillatory shear or SAOS), isothermal calorimetry, and mechanical testing. An equal workability of each mix design is ensured through the use of a superplasticizer. Results from rheology and calorimetry show satisfactory cohesion and heat evolution for RB content up to 70%. At this high substitution level with only 30% of OPC, the 28-day compressive strength still reached 16 MPa. Mechanical testing on OPC/RB mortar shows satisfactory results, particularly for OPC replacement up to 50% with a compressive strength higher than 30 MPa after 28 days. A life cycle assessment (LCA) focusing on global warming potential (GWP) is conducted to quantify the potential environmental improvement of the optimized binder mixtures during the production stage. This combined methodology is promising for the development of environmentally friendly construction materials.