Experimental effect of pre-treatment of rubber fibers on mechanical properties of rubberized concrete

The current experimental research encompasses the outcome of the pre-treatment of rubber fiber (RF) derived from discarded tires when utilized in concrete as a limited substitution of sand by its volume. To overcome the causes of reduction in strengths of concrete after inclusion of rubber particles (RP) as fractional or complete replacement of fine aggregates, three different pre-treatments are adopted in this study by using sodium hydroxide (NaOH), hydrochloric acid (HCL), and water spray method, and the obtained results compared with controlled concrete and rubberized concrete (RC) with untreated RF. The fine aggregates from concrete are swapped with discarded tire RFs of size 2.36–1.18 mm and a maximum length of 20 mm from 0% to 20% with an increase of 5%. RC's mechanical properties are studied, and they are contrasted with those of controlled concrete that has no sand substitute. Fresh properties like workability, density, and hardened properties such as compressive, flexural, and splitting tensile strengths were assessed. In addition to this abrasion resistance to check wear and tear of concrete, load–displacement relationship, elastic modulus, and microstructural analysis of RC were also studied. The research study investigated that the strengths varied with the pre-treatment methods adopted. Altered concrete with RFs has shown the enhancement in strengths for a replacement of sand by RFs up to a certain limit of replacement. The maximum reduction in strengths is observed for concrete with a 20% inclusion of untreated RFs as a substitution for sand. Concrete with 10% RFs pretreated with NaOH and HCL has shown enhancements in strength and decline in rate of reduction for strengths as compared to controlled concrete and concrete with untreated RFs. Based on the major findings of this study, the better strain rate behavior of RC was observed.