Fillers to improve the ductility and impermeability of crumb rubber concrete

Crumb rubber concrete (CRC), a type of eco-friendly concrete materials, has attracted pronounced interest in the field of infrastructure construction and waste management. However, special attention should be paid to its permeability since it is an important indicator to determine its service life for building structures, especially in coastal regions. Present study discusses the feasibility of pozzolanic fillers to improve the ductility and impermeability of CRC. By incorporating fly ash (FA), silica fume (SF), and ground granulated blast furnace slag (GGBFS), fresh properties, mechanical strength and chloride resistance of CRC were evaluated. Results show that the fillers adopted enhance the toughness of CRC in terms of ductility index considering splitting-tensile and compressive strength, among which SF has the most positive effect. Micro-aggregate effect of FA particles, high active silica content of SF and more Friedel's salt formation are the main reasons for the improved impermeability of CRC. Radar charts are plotted to analyze the overall performance of CRC with fillers. Relative area values indicate that SF exhibits the most significant improvement in CRC performance, followed by GGBFS and FA.