Durability Performance and Thermal Resistance of Structural Self-Compacting Concrete Improved with Waste Rubber and Silica Fume

Waste rubber takes many years to decompose, and thus the increasing number of tires in the world can be characterised as an important environmental issue, which generated the idea of implementing crumb rubber in structural self-compacting concrete (SCC). According to previous studies, up to 15% recycled rubber and 5% silica fume can be used to achieve the required properties of SCC in reinforced structural members with congested reinforcement, both in the fresh and hardened state. Most studies have focused on investigating the mechanical properties of self-compacting rubberised concrete (SCRC), and only a small number of studies investigated the durability and thermal properties, with contradictory findings. This study aims to determine the influence of crumb rubber and silica fume on the durability and thermal properties of SCC, with an emphasis on the selection of environmental exposure classes, the safety of using such a material in reinforced concrete members, and additional serviceability and durability requirements. This was further advanced by investigating the micro-structure of hardened SCC with recycled rubber and silica fume using a scanning electron microscope (SEM). Test results indicate that the combining effect of crumb rubber and silica fume has a positive impact on the thermal and durability properties of SCC.