Abstract
Concrete researchers have incorporated various waste materials in the concrete matrix as a part of lowering its contribution to global carbon dioxide emissions. Plastic is one of the most common waste materials globally and has been targeted by various concrete researchers, in many forms to incorporate in concrete. The composite coarse aggregates are among one of the choices. The current study evaluated the fresh, hardened and microstructure properties, in addition to the effect of curing temperature on the strength development of composite aggregate concrete at various replacement levels of coarse aggregates in comparison to normal and lightweight concrete. The compressive strength, flexural strength and modulus of elasticity values of the resulting concrete decreased by 0.72, 0.73 and 0.36 times that of normal concrete, respectively, at 100% replacement of composite aggregate. In addition, the values of compressive strength decreased by 9% to 17% with increase in the curing temperature from 20 to 40 degrees C. Microscopic investigation showed better interlocking between cement paste and the developed aggregate in this study. Moreover, empirical models were also proposed to predict the flexural strength and elastic modulus of concrete containing composite aggregate in terms of compressive strength. As a whole, the composite aggregates have demonstrated their capacity to be used for different lightweight structural construction purposes.