Effect of Crushed Glass on the Shear Behavior of Recycled Unbound Granular Aggregates Incorporating Crumb Rubber

The shear strength is one of the most critical mechanical properties influencing pavement rutting performance for unbound granular aggregates. Very limited research has examined the shear characteristics of blended recycled waste materials, although the use of recycled and waste materials is becoming increasingly popular in real-life civil and construction projects. In this work, for the first time, the large direct shear test (LDST) apparatus was utilized with the aim of investigating the effects of introducing waste crushed glass (WCG) on the shear response of recycled unbound granular materials, namely crushed rock (CR) and recycled concrete aggregate (RCA), containing fine crumb rubber (R). The outcome of the investigative study indicates that introducing WCG not only increased the internal friction angles, but also the cohesion values of the blends. The inclusion of 3% WCG resulted in the highest shear strength. However, beyond 3%, increasing the amount of WCG decreased shear strength. The results of this study show that RCA and CR mixed with 1% R along with three varied percentage inclusions (1%, 3%, and 5%) of WCG fulfilled the requirements in terms of shear strength for base and subbase of pavements.