Comparative study on the properties and high temperature resistance of self-compacting concrete with various types of recycled aggregates

Construction and demolition activities generate numerous waste that could be reutilized as recycled aggregates. The replacement of natural aggregate with recycled aggregate generally has negative impact on the performance of conventional concrete. This impact is found to be less significant in self-compacting concrete (SCC), owing to the better quality of binder which modifies the interfacial transition zone and lesser amount of coarse aggregates used. Considering the wide sources of recycled aggregates such as concrete, bricks and blocks, few studies were conducted on comparing the performance of SCC incorporating different types of recycled aggregates. In addition, since SCC is more commonly used in high-rise buildings which may experience fire risks, it is important to ascertain the corresponding high temperature resistance. In this paper, three different types of recycled aggregates are considered, namely recycled concrete aggregate (RCA), recycled brick aggregate (RBA), and recycled concrete block aggregate (CBA). 100 % replacement is feasible for SCC-CBA and SCC-RCA because of the minor strength reductions. The results also showed that the RBA and CBA concretes outperformed the NA concrete at high temperature (400 °C and 600 °C). RBA is suggested to partially replace natural aggregate, since it gives inferior performance at room temperature, but it is more recommended to be used in high temperature environments.