Effects of EAF Slag, Steel Fiber, and Polyurea Coating on Mechanical Properties and Sulfuric Acid Resistance of Concrete Pipes

In this study, the effect of using electric arc furnace (EAF) slag for infrastructure pipes was investigated. By using EAF slags and natural aggregates, normal and high strength concrete mixtures with and without steel fiber were produced for concrete pipes. The physical, mechanical, and permeability properties and fracture behavior of these concrete mixtures were determined. The usability of EAF slags in concrete and reinforced concrete pipes with acidic corrosion risk was investigated by exposing the concrete samples to sulfuric acid attacks. In addition, some concrete samples and concrete pipes were covered with polyurea material. Thus, apart from using EAF aggregates, the effect of a polyurea coating on the resistance of concrete pipes against acid effects and crushing strength were also investigated. When EAF aggregates were used instead of natural aggregates, the mechanical properties and resistance of the concrete against acidic corrosion increased. The polyurea coating on concrete pipes provided a more obvious improvement against acid attack and increased the crush strength of the pipes. As a result, it is possible to produce concrete pipes with a longer service life by using EAF aggregates or polyurea coatings.

The slag produced as waste in iron and steel plants is one of the major problems for producers. EAF slag can be used in concrete production by substituting natural aggregates. Concrete pipes are widely used in infrastructure sewer applications. However, the chemical environment in the sewage causes physical and chemical deterioration of the concrete. One of the effective ways to protect reinforced concrete structural elements against acid corrosion is coating the inner surface of the concrete pipe with polyurea. This study was aimed to determine the resistance of the reinforced concrete infrastructure pipes against the sulfuric acid attacks when they are produced using EAF slag aggregates or if their inner surfaces are covered with a polyurea material. In addition, the effects of these applications on the mechanical performance of concrete and reinforced concrete pipes were determined by concrete tests in the laboratory and crush strength tests in industrial products. As a result of the study, both the use of EAF aggregates in the production of pipes or the coating of the inner surfaces of the pipes with a polyurea material were found beneficial in terms of both mechanical behavior and resistance to acid effects in infrastructure pipes. However, in the case of the polyurea coating on the inner surfaces of the pipes, the resistance to acid attacks improved more significantly compared to the use of electric arc furnace (EAF) aggregates.