Optimization of concrete containing waste crumb rubber mix design for thermal insulating applications using Taguchi method

This study investigates incorporating waste crumb rubber as a cost-effective aggregate in concrete to improve properties and address environmental concerns. Using the Taguchi method, mix proportions were optimized based on water/cement ratio (0.45 -0.60 wt/wt), volume of water (38 -44 cm 3 ), sand/cement ratio (0.1 -0.4 wt/ wt), and crumb rubber content (3 -15 wt%). The concrete properties were studied including unit weight, compressive strength, water absorption, sulphate attack resistance, and thermal conductivity. The obtained results revealed a noteworthy reduction in unit weight, achieving structural lightweight concrete (1598 -1746 kg/ m 3 ) as per ASTM C330/C330M-14. However, crumb rubber had an adverse impact on compressive strength (7.45 -31.26 MPa). The sand/cement ratio significantly improved compressive strength, water resistance, and sulphate attack resistance. Notably, crumb rubber improved thermal insulation properties (0.51 -0.67 W/mK). The optimized mix outperformed commercial alternatives in terms of thermal insulation, suggesting that crumb rubber concrete could be a cost-effective, sustainable, and high-performance thermal insulator in energy -efficient construction materials.