Research on the Classification of Concrete Sulfate Erosion Types in Tumushuke Area, Xinjiang

Abstract

Tumushuke, a significant node of “the China–Pakistan Economic Corridor” and “the Silk Road Economic Belt”, is strategically located in the southern region of Xinjiang. Due to the widespread distribution of its salty soils, concrete construction safety is significantly compromised. The construction of this project used sulfate-resistant cement, which was costly to construct. Six groups with varying sulfate immersion concentrations were set up to perform sulfate erosion tests and sulfate freeze–thaw coupling tests, respectively, based on the survey of the distribution of sulfate concentration in the area. The Tumushuke area’s concrete erosion kinds were classified using a microanalysis of the degraded concrete. The findings indicate that the concrete primarily exhibits gypsum-type erosion when the sulfate concentration is greater than 20,000 mg/kg, ettringite–gypsum-type erosion when the sulfate concentration is between 15,000 and 20,000 mg/kg, and ettringite-gypsum-type erosion when the sulfate concentration is less than 15,000 mg/kg. The erosion product, carbon–sulfur silica-calcite, also occurs under sulfate freeze–thaw coupling. In the Tumushuke area, ettringite-type erosion damage is primarily found in low-sulfate areas in the southwest and a small portion of the northeast. In contrast, higher-sulfate areas in the central northward area are primarily affected by ettringite–gypsum and gypsum-type erosion damage. The results of this study can provide a basis for adopting different anti-sulfate erosion measures for engineering construction in different regions.