Effect of temperature and acidity of sulfuric acid on concrete properties

Concrete corrosion caused by sulfuric acid attack is a known phenomenon in sewer systems, resulting in significant economic losses and environmental problems. However, there is a scarcity of reported laboratory simulations and experimental work investigating the contributing factors controlling the corrosion. In this investigation, funded by the U.K.'s Engineering and Physical Sciences Research Council (EPSRC), the effect of temperature and the acidity of sulfuric acid solution on concrete specimens extracted from brand-new concrete sewers has been investigated. In this investigation, the concrete samples are submerged in three sulfuric acid solutions (pH = 0.5, 1, and 2) for 91 days under different temperatures (10, 20, and 30°C). Mass loss and compressive strength of the concrete specimens were tested and recorded at 7, 14, 28, 42, 56, and 91 days, providing interesting data for visualizing the changes taking place in the concrete samples (change in properties) during the time of immersion. The results revealed that samples overall mass increased at the early stages of the corrosion process. It also was observed that the overall mass of the samples decreased significantly at the later stages of the testing process with respect to the acidity of the solutions used. Although the change in temperature did not have a significant effect on the compressive strength of the tested samples, the rise in temperature, however, had a considerable effect on the mass loss of the concrete samples that were immersed in the most aggressive solution (i.e., pH = 0.5 and temperature =a 30°C) at 91 days. This research clearly demonstrated a high correlation between the acidity of the solution and the rate of corrosion with respect to time.