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Concrete wastewater infrastructures are important to modern society but are susceptible to sulfuric acid attack when exposed to an aggressive environment. Fibre-reinforced mortar has been adopted as a promising coating and lining material for degraded reinforced concrete structures due to its unique crack control and excellent anti-corrosion ability. This paper aims to evaluate the performance of polyethylene (PE) fibre-reinforced calcium aluminate cement (CAC)–ground granulated blast furnace slag (GGBFS) blended strain-hardening mortar after sulfuric acid immersion, which represented the aggressive sewer environment. Specimens were exposed to 3% sulfuric acid solution for up to 112 days. Visual, physical and mechanical performance such as water absorption ability, sorptivity, compressive and direct tensile strength were evaluated before and after sulfuric acid attack. In addition, micro-structure changes to the samples after sulfuric acid attack were also assessed by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) to further understand the deterioration mechanism. The results show that overall fibre-reinforced calcium aluminate cement (CAC)-based samples performed significantly better than fibre-reinforced ordinary Portland cement (OPC)-based samples as well as mortar samples in sulfuric acid solution in regard to visual observations, penetration depth, direct tensile strength and compressive reduction. Gypsum generation in the cementitious matrix of both CAC and OPC-based systems was the main reason behind the deterioration mechanism after acid attack exposure. Moreover, laboratory sulfuric acid testing has been proven for successfully screening the cementitious material against an acidic environment. This method can be considered to design the service life of concrete wastewater pipes.

The external desulphurization of molten iron has become an important step in the production of steel and iron. The melting temperatures of high calcium desulfurization slag, which were taken from Shougang Shuicheng Iron and Steel (Group) Co. Limited, were investigated on basis of the method of hemisphaerium temperature. The contents of CaO, Al2O3 and CaF2 in the slag were adjusted in 47%-53%, 14%-20% and 2%-10% respectively by adding analytical reagent Ca (OH)2, Al2O3 and CaF2 using orthogonal design. The results show that the melting temperature of desulfurization slag decreases obviously with the increase of the content of Al2O3 between 14% and 20%, and decreased markedly with the increase of the content of CaF2 lower than 8%. The impact to the melting temperature of the high calcium slag is as follows: Al2O3 > CaF2 > CaO.