Waste Rubber Pre-treatments and Their Effects on Compressive and Flexural Strength of Modified SIFCON

Slurry-infiltrated fiber concrete (SIFCON) is a comparatively new and unique steel fiber-reinforced concrete (FRC) form. SIFCON possesses many desirable characteristics, including high strength and ductility. Sustainable concrete is one of the most critical types of concrete for the current environment. An enormous volume of waste rubber tires is produced globally due to the expansion of the automobile industry. This study's primary purpose is to assess the impact of employing pre-treated waste rubber tires in slurry-infiltrated fiber concrete on its flexural and compressive strengths. Based on flexural and compressive strengths, an experimental program was conducted to evaluate the flexural and compressive strengths of SIFCON containing 4% steel fiber and 6%, 8%, and 10% waste rubber. Different pre-treatment methods were used to improve the bonding between the cement paste and rubber particles, including Na(OH) solution, Ca(OH)2 solution, and pre-treatment using Cempatch AB solution. Compressive and flexural strength decreased with increasing waste rubber content, up to 43% and 37% for a 10% waste rubber content, respectively. Moreover, The test results showed that the pre-treatment of chopped rubber with NaOH solution produced the highest values for compressive and flexural strength, giving strong polarity groups to the surface of the rubber and generating a strong chemical interaction between the rubber and the cement matrix.