Effects of breakage of construction and demolition waste materials (C&DWMs) at asphalt mixtures

This study aims to evaluate the effects of breakage of construction and demolition waste materials (C&DWMs) on aggregate gradation, aggregate characteristics, moisture damage, and resilient modulus using Hot Mix Asphalt (HMA). Asphalt mixtures containing 0%, 25%, 50%, and 75% C&DWM wastes were investigated. The characteristics of C&DWMs were investigated through the surface inspection, the particle size distribution, the water absorption, and the density tests. The indirect tensile strength test, the tensile strength ratio test, and the indirect tensile stiffness modulus test were performed. Moreover, the analysis of variance (ANOVA) and damage analysis were also performed. The results showed that the amount of optimum asphalt content increases as the dosage of C&DWMs increases. The change in gradation has led to a variation in the properties of coarse, fine, and combined aggregates. The breakage of C&DWMs during mixing and compaction processes contributes to the redistribution of aggregate particles after mixing and compaction processes. The breakage has led to better resilient modulus and lower water stability exhibited by C&DWMs mixes than control mixes. The damage analysis and ANOVA testing indicate that asphalt mixtures with no more than 50% C&DWMs have a performance like that of the control mix. In this regard, the pavement section with 0%, 25%, and 50% of C&DWMs achieved a design life of around 19 years. Although the results were encouraging, the C&DWMs asphalt mixtures require more investigation in future studies. This would elevate the use of C&DWMs in the pavement industry and promote more sustainable asphalt mixtures.