Experimental Study of the Mechanical Behaviour of Brick Waste Concrete and Analytical Prediction of its Elastic Modulus as a Three-Phase Composite Material

Abstract

This paper focuses on the characterization of the mechanical behaviour of concrete incorporating different percentages of brick waste aggregates (BWA). Compressive strength, splitting tensile strength and elastic modulus of this material were measured based on standard laboratory tests and its microstructure was characterized based on scanning electron microscope (SEM) observations. A decrease in these properties was observed with the increase of BWA substitution ratio. However, this decrease remains moderate up to a substitution percentage of 30% (about 12% for compressive strength and elastic modulus and 8% for splitting-tensile strength). In addition, an increase in the concrete porosity was observed with the increase of BWA substitution ratio, which can explain the decrease observed in the measured mechanical characteristics. SEM views on concrete incorporating 100% of BWA showed that the interfacial transition zone (ITZ) and the cement paste present a higher porosity when compared to those of the reference concrete made with natural aggregates.Finally, a micromechanical analytical homogenization model predicting the elastic modulus of brick waste concrete (BWC) according to its composition is proposed where BWC is modelled as a three-phase composite. A good agreement was found between analytical predictions and experimental results proving that BWC mechanical characteristics are mainly governed by BWA mechanical properties and their volume fraction within concrete.