Properties of concrete mixes containing tire rubber and brick powder exposed to sulfuric acid and cured in water: A comparative study

The existing literature shows that rubberised concrete suffers from reduced mechanical properties when it is compared with normal density non-rubberised concrete. This is due to the underlying reduced bonding between tire rubber and other concrete ingredients. The massive sulfuric acid attack in rubberised concrete must have additionally discouraged researchers from attempts to assess the phenomenon of improving performance of rubberised concrete. A research was undertaken to compare the properties of concrete mixes containing tire rubber replacing coarse aggregate and waste clay brick powder (WCBP) replacing cement exposed to sulfuric acid and cured in water. Concrete cubes and cylinders of concrete grades of 20 MPa, 25 MPa and 30 MPa were immersed in 5% sulfuric acid solution up to 90 days following moist curing of 27 days. Other concrete cubes and cylinders were cured in water for comparison. The compressive strength findings indicated that all the specimens exposed to sulfuric acid had lost more than 57% of their compressive strengths after 90 days with reference to the corresponding samples cured in water. In contrast, out of all concrete mixes investigated for all concrete grades, never were the split tensile strength losses of the specimens exposed to sulfuric acid greater than 43.1% compared with those cured in water. In each exposure condition, concrete mixes with 5% WCBP showed slight improvements in compressive and split tensile strengths in contrast with the conventional concrete mixes. Visual inspection of the specimens illustrated depositions of flaky or white substances on the outer layers of specimens exposed to sulfuric acid compared with specimens cured in water. Moreover, the split tensile strengths of specimens were not severely affected with exposure to sulfuric acid in comparison with compressive strengths. Eventually, the research identified the existence of WCBP in rubberised concrete as a promising criterion of minimising strength losses of rubberised concrete.