Reutilization of clay brick waste in mortar: paste replacement versus cement replacement

Abstract

Clay brick waste is one of the largest construction wastes by output. Traditionally, clay brick waste is reutilized in mortar/concrete as aggregate replacement after crushing or as cement replacement after grinding, but these two methods of reutilization have certain adverse effects on the quality of mortar/concrete. In this study, a new method, named the paste replacement method, was developed; in this method, clay brick dust (CBD) is used to replace cementitious paste with the paste composition kept unchanged. To compare the effectiveness of the paste replacement and cement replacement methods, mortar mixes with different replacement ratios of CBD (either as paste replacement or cement replacement) were tested to study their workability, strength, and microstructure. The test results showed that CBD added as paste replacement improved the strength and microstructure and substantially reduced the cement content, whereas adding CBD as cement replacement decreased the strength and loosened the microstructure. Hence, the paste replacement method is more promising for recycling clay brick waste and producing eco-friendly concrete.