Increasing service life of concrete in sewage treatment plants using silica fume and natural zeolite

Abstract

Microbial attacks rapidly degrade concrete structures in wastewater facilities, leading to brief service lifespans. Hence, producing concrete resistant to chemical and sulfuric acid corrosion is more cost-effective. In the present study, a total of six concrete mixtures incorporating 7.5% silica fumes (SF) and 10% natural zeolite (ZE) were immersed in 0.5% and 1% sulfuric acid solutions with a maximum pH threshold of 2 and 1, respectively, for 70 weeks. The specimens were regularly monitored for surface deterioration, mass change and crushing load change. To better understand the relationship between the pore structure of concrete mixtures and resistance to sulfuric acid, various durability tests such as rapid chloride penetration, water absorption, electrical resistivity and chloride diffusion coefficient were performed. Based on the results obtained, converting calcium hydroxide into calcium silicate hydrate gel through pozzolanic reactions and then refining the porosity of concrete with silica fumes (SF) and natural zeolite (ZE) was effective in enhancing the resistance of concrete to attack by sulfuric acid of relatively low concentration. As a result, using silica fumes (SF) and natural zeolite (ZE) is a lower-cost method for reducing corrosion rates to extend the service life of facilities, particularly in lower concentrations.