Performance of crumb rubber concrete made with high contents of heat pre-treated rubber and magnetized water

For many years, several research has been conducted to investigate the use of tyre rubber waste as a substitute for concrete fine and coarse aggregates to decrease its unfavourable impacts on the environment. This resulted in producing crumb rubber concrete (CRC) with limited compressive strength. CRC strength enhancement approaches were introduced mostly through pre-treating the rubber aggregate using chemicals before using in concrete with impractical methodologies and contradictory findings. In the current research, the performance of CRC containing high contents of heat pre-treated rubber and magnetized water (MW), prepared in magnetic field strength of 1.4 T, was investigated. Rubber content, heating temperature, heating time, MW content, and water magnetizing time were the variables in this experimental investigation. Measurements of the concrete workability, mechanical properties, impact resistance, and microstructure analyses were conducted in this study. Water characterization before and after magnetization was also carried out. Promising performance was shown by CRC contained heat pre-treated rubber at 200 °C for 2 h and 100% MW treated for 24 h. These conditions resulted in compressive strength recovery of 74% and impact resistance enhancements of 2.2 times at first crack and 92% at ultimate failure when using rubber content of 40%. The microstructural analyses showed that rubber heat pre-treatment burnt out most of the unwanted materials in rubber aggregate, created an outer hard shell on the rubber particles, and decreased the zinc presence in rubber from 8.32% to 1.89%, which all resulted in CRC compressive strength and impact resistance enhancements.