Effects of different kinds of recycled fine aggregate on properties of rendering mortar

Abstract

This study investigated the properties of rendering cement mortars prepared with three different types of recycled fine aggregates (RAs). Type I was a fine RA obtained from a recycling plant in which mixed demolition wastes were suitably treated by mechanical crushing, sieving, and sorting operations. Types II and III were fine RAs obtained from crushing two different size fractions (50–150 and 150–250 mm) of construction and demolition waste rubbles collected from a sorting facility. Two series of rendering mortar mixes were prepared with a constant water/cement and a constant aggregate/cement ratios of 0.55 and 3, respectively. River sand and natural crushed rock fines were originally used as aggregates in the two series separately, and they were consistently replaced by 25, 50, 75, and 100% by each of the three types of recycled aggregates. The experimental results showed that mechanical properties such as compressive strength, flexural strength, and modulus of elasticity of the mortars prepared with the RA were lower than the mortars made with the natural aggregates. Nevertheless, the bond strength at the interface between the mortar and masonry bricks determined by the Triplet test was found to be higher for the mortars prepared with the RAs.

Keywords:

• rendering mortar
• recycled fine aggregate
• triplet test
• mechanical properties

Acknowledgments

The authors would like to thank Sun Hung Kei Properties Ltd and the Hong Kong Polytechnic University for funding support.