Authors: Umesh Seetha, Dr. Ala Satyanarayana
Abstract: This study investigates M40 standard-grade and M70 high-strength concrete incorporating waste tyre rubber as partial replacement of natural fine and coarse aggregates together with silica fume. The experimental programme evaluates workability, compressive strength, split tensile strength, flexural strength, stress-strain behaviour, Young's modulus, rebound number, ultrasonic pulse velocity, sorptivity and resistance to 5% MgSO4, HCl and H2SO4 solutions. The mixes include control concrete, concrete with 4% silica fume, concrete with 4% coarse waste tyre rubber and silica fume, and concrete containing both fine and coarse waste tyre rubber. The study reports 264 specimens, with 132 specimens for each concrete grade. Results show that increasing tyre-rubber content reduces workability and mechanical strength because of weak bonding between rubber particles and cement paste. The target mean strength was obtained for rubberized concrete con-taining 4% coarse rubber and 4% silica fume, while the required target mean strength was not achieved for M70 rubberized concrete. Non-destructive, sorptivity and chemical-exposure results provide additional assessment of quality and durability.
