Performance Studies of Pavement Quality Concrete Mix Incorporating Beneficiated Recycled Concrete Aggregates

Abstract

Incorporating recycled concrete aggregate (RCA) is one way of recycling and using demolished concrete waste. However, it is an established fact that recycled concrete aggregates used without surface treatment/beneficiation exhibit inferior properties in comparison with their natural counterparts. Various techniques for beneficiation of RCA have been proposed by different researchers over the period of time. This study involves incorporations of recycled concrete aggregates upon beneficiations in preparation of pavement quality concrete (PQC) mixes. Four different techniques for beneficiation of recycled concrete aggregates were adopted in the study, i.e. beneficiation by mechanical abrasion, beneficiation by water soaking and abrasion, beneficiation by HCL soaking and abrasion and beneficiation by H2SO4 soaking and abrasion. PQC mixes incorporating beneficiated recycled concrete aggregates were studied for their mechanical properties in fresh and hardened states. Laboratory investigations showed improvement in physical and mechanical properties of recycled concrete aggregates upon beneficiation. Among different beneficiation techniques studied, beneficiation by H2SO4 soaking and abrasion was found to be most efficient in removing the adhered mortar by nearly 22% of the weight of recycled aggregate sample. The improvement in properties of recycled concrete aggregates upon beneficiation helped in improving the properties of the respective concrete mixes as well. These improvements were observed to be highest for mix prepared with recycled concrete aggregates beneficiated by H2SO4 soaking and abrasion to the order of approximately 35% for compressive strength and 18% for flexural strength.