Bringing recycled aggregate to its full potential

This paper simplifies recycled aggregate testing procedures. Eleven physical and mechanical properties of aggregate are investigated: uncompacted bulk density; compacted bulk density; particle density; water absorption; aggregate crushing value; dry strength; wet strength; contaminant; weak particle; flakiness index; and particle shape. The experiments conducted are based on Australian Standard 1141 and HB 155. Eleven recycled aggregate samples collected from construction and demolition sites and centralised recycling plants located in Brisbane, Gold Coast and Sydney, Australia are used. The simplified testing procedures are established by undertaking a regression analysis among different aggregate tests. From the results, three groups of tests are refined: group I (density, water absorption, strength and contaminant); group II (weak particle); and group III (shape). By implementing the prediction equations, reduction in testing by about 63·6% is achieved with full understanding of the quality of recycled aggregate. A reduced testing time can be used to test the properties of recycled aggregate at the source locations and to help realise the potential of recycled aggregate in high-grade concrete applications without averaging the recycled aggregate quality in centralised recycling plants.