1) Dr, The University of Newcastle, Priority Research Centre For Energy, Australia,

2) Professor Emeritus, The University of Newcastle, Priority Research Centre For Energy, Australia,

3) Undergraduate student, The University of Newcastle, Discipline of Civil Engineering


With the increasing emphasis on all aspects of sustainability in buildings, it is important to fully utilize the properties of masonry units for their full life cycle. Clay bricks can be recycled in the brick manufacturing process, but they also have potential in a crushed form to be used as a concrete aggregate replacement. This paper presents the findings of a laboratory investigation into the use of crushed brick aggregate as a replacement for fine and/or coarse aggregate in concrete.

Aggregate tests on crushed brick aggregate were performed as well as compressive strength and indirect tensile strength tests on hardened concrete specimens for recycled brick and conventional aggregate concretes for water-cement ratios ranging from 0.4 to 0.7 at 0.05 intervals. The research investigated not only the effect of aggregate type on concrete mechanical properties, but also the influence of the aggregate porosity on concrete workability. In addition, the nature and influence of the contact layer between the cement paste and the aggregate particles on the concrete properties was studied using optical microscopy and image analysis techniques.

Reductions in concrete tensile and compressive strength were observed for the lower water-cement ratio concrete mixtures when fine and/or coarse aggregates were replaced with crushed brick. However, it was found that the porosity of the brick aggregates had a positive curing impact on the hardened concrete properties for concrete mixtures of higher water-cement ratios by storing water and preventing internal shrinkage cracking.


Keywords: recycled brick aggregate, sustainability, cementitious composite, image analysis technique