Fracture energy of fiber-reinforced and rubberized cement-based composites: A sustainable approach towards recycling of waste scrap tires

Using crumb rubber particles obtained from end-of-life tires as aggregate in concrete can reduce the environmental overburden caused by the huge accumulation of these scrap tires. However, reduction in the mechanical properties of concrete is observed with the incorporation of rubber aggregates. To counter this detrimental effect of crumb rubber in concrete, amorphous metallic fibers are added to balance the loss in strength and durability issues. Mechanical characteristics along with the fracture energy of rubberized fiber-reinforced mortar are presented here. Four mortar mix compositions were investigated; the first one is reference mortar (control mortar), the second mix containing 30 kg/m3 of metallic fibers, the third mix containing 30% of rubber aggregates as replacement of sand by equivalent volume and fourth containing both rubber aggregates and metallic fibers with the dosage 30% and 30 kg/m3, respectively. Compression tests, modulus of elasticity and direct tension tests were conducted for mechanical characterization. Deformation capacity, residual post-cracking strength and fracture energy of these composite mortar mixes were evaluated through uniaxial direct tension tests. The fracture energy was determined from the obtained complete softening curves. Test results show a reduction in mechanical properties with the incorporation of crumb rubber as aggregates in mortar. However, a significant increase in fracture energy was observed in rubberized fiber-reinforced mortar mixes. Moreover, the mortar mixes containing both rubber aggregates and metallic fibers show positive synergetic effect resulting in enhanced post-cracking residual tensile strength, strain capacity and energy dissipation capacity.