Investigating the mechanical properties of concrete using non-treated crumb rubber and silica fume

This study investigates the potential application of non-treated crumb rubber (CR) as a partial sand replacement in concrete while determining the optimal CR-to-sand ratio. Additionally, silica fume was incorporated at 2.5% and 5% levels to assess its influence on mechanical properties. A total of 10 concrete mixes were evaluated for compressive strength, splitting tensile strength, and water absorption. The results indicate that a 10% CR substitution yielded the highest improvement in compressive strength (34.7%) and tensile strength (36.85%). Although silica fume shows minimal improvement on strength, it effectively reduced water absorption, with the lowest absorption (1.15%) observed at 15% CR and 2.5% silica fume content. These findings suggest that crumb rubber concrete (CRC) is a viable, sustainable alternative due to the enhanced concrete mechanical performance and for its important role in environmental protection by integrating such waste in concrete industry.