Environmental performance and durability of concrete incorporating waste tire rubber and steel fiber subjected to acid attack

Corrosion of sewage concrete pipes is a major dilemma in the modern world and annually considerable amounts of money are spent for the maintenance. On the other hand, the use of waste materials in concrete mixes has recently attracted the attention of engineers due to the environmental importance. In this study, the effects of different dosages of steel fibers (SFs) by volume (0, 0.25, 0.5, and 1. %) and different contents of recycled crumb rubber (CR) waste with different fine aggregate (sand) replacement ratios (0, 10, and 20%) were evaluated on the durability properties. The corrosion resistance of the specimens was measured in terms of weight loss, crushing load, ultrasonic wave velocity, impact resistance, and X-ray diffraction analysis (XRD) in different immersion cycles of 15, 30, 45, 60, and 90 days. The most important factors affecting on crushing load, weight, ultrasonic wave velocity and impact resistance were determined by using variance (Anova) method. Also, global warming potential (GWP) was studied as a criterion for CO2 emissions. According to the results, addition of 10% CR and 0.25% SF could create more efficacies for better performance in both terms of durability and crushing load. Besides, the specimen containing 10% CR and 1% SF exhibited the highest performance in the impact resistance. The GWP evaluation shows that the use of CR reduces the amount of CO2 emitted from the production of raw materials consumed. Although adding SFs to the concrete slightly increases CO2 emissions, effects of synthetic CR and SF can be of great benefit in improving durability and impact resistance in sulfuric acid solution.