Ceramic waste powder: from landfill to sustainable concretes

Incorporating solid waste materials in concrete has three advantages – the immediate environmental benefit of recycling a material from landfills, reducing the negative impact of cement production and preserving natural resources. Ceramic waste powder (CWP), produced during the process of polishing ceramic tiles, is dumped in landfills and can cause soil, air and groundwater pollution leading to serious environmental problems. CWP is mainly composed of silicon dioxide and aluminium oxide (>80%), making it a good candidate in concrete manufacturing. This study investigated the use of CWP in producing conventional (CV) concrete and self-compacting concrete (SCC). CWP was used as a partial cement replacement: by 10, 20, 30 and 40% in CV mixtures and by 28 and 57% in SCC mixtures. Fresh properties, compressive strength development and durability characteristics of the different concretes showed that CWP could be successfully used as a partial cement replacement. The optimum replacement for CV mixtures was found to depend on the concrete strength grade. For the 25 MPa mixture, the optimum replacement level was 10–30%, while it was 20 or 30% for the 50 MPa mixture. For SCC mixtures, as far as strength is concerned, a 28% replacement level can be used while, for fresh and durability characteristics, both 28 and 57% are acceptable.