Chemical Resistance of Synthetic Fiber-Reinforced Concrete Pipes in Highly Corrosive Environments

Among different components of the US highways and roads, concrete pipes are one of the most important parts of these infrastructure. Currently, most of the concrete pipes that are produced in the US are made from steel-reinforced concrete composite, and this system is prone to deterioration and steel corrosion during the service life of these pipelines. In this study, a newly developed synthetic fiber-reinforced concrete composite was studied to determine its chemical resistance in highly acidic environments with accelerated aging methods. Actual reinforced concrete pipes with 0.54% fiber volume fractions were immersed in low pH solutions and elevated temperatures. The D-load test results showed that specimens that were immersed in pH2 solutions lost their ultimate D-load capacity by 20% after 1 year, and pH4 specimens showed an 18% load decrease at the same time. Furthermore, by using SEM and EDX analysis, the chemical composition of specimens that were extracted from these pipes was analyzed. The results showed that at the early stages of the immersion tests, the surface of the pipes in pH4 solution did not absorb a significant amount of sulfur, and it shows that these specimens have not deteriorated significantly. With longer immersion duration, the amount of sulfur element on the surface of the specimens increased gradually, and for pH2, the surface was mostly saturated after 5 months of immersion. For pH4, this value was constantly increasing, and similar to the mechanical tests, pH4 results were converging to the same value of pH2 results. The findings of this research would pave the road to determine the service life of this composite in highly corrosive acidic environments.