Reutilizing clay brick dust as paste substitution to produce environment-friendly durable mortar

Abstract

Clay brick waste is being generated in huge quantity every year due to increasing construction and demolition activities, causing serious waste is disposal problems. In traditional cement substitution or aggregate substitution methods, a limited amount of the clay brick waste can be reused in mortar or concrete to substitute part of cement or aggregate. This study attempted to reutilize clay brick dust (CBD) based on paste substitution method (by substituting a portion of the paste by an equal volume of CBD without changing the paste composition and water/cementitious materials ratio) to produce mortar, and conducted tests to study its workability in terms of flow spread, and durability in terms of sulphate resistance, water resistance and shrinkage resistance. The findings revealed that reutilizing CBD as paste substitution would increase the superplasticizer demand, but could substantially enhance the sulphate, water and shrinkage resistances, and reduce the cement content and associated carbon footprint. It was shown that up to 20% CBD by volume of the mortar may be added to reduce the cement content by 33% without causing adverse effects. Such percentage reduction in cement content is larger than possible with cement or aggregate substitution.