Damage Evolution of Concrete under the Actions of Stray Current and Sulphate

Abstract

Based on the mechanism of stray current generation in underground structures, the concrete durability test device for stray current and sulphate in typical soil environment was designed to study the damage of concrete under the action of stray current and sulphate. The deterioration law of concrete under the action of stray current and sulphate was studied by microscopic techniques such as scanning electron microscopy (SEM) and X-ray diffraction (XRD). The microstructure of corroded concrete was observed to determine the phase composition of erosion products. The damage performances such as quality, strength, and dynamic elastic mode of corroded concrete were performed. The experimental results show that, under the action of stray current, the products of sulfate-eroded concrete are mainly gypsum, ettringite, and thaumasite; the stray current accelerates the hydration process of cement and the erosion of concrete by sulfate; when the concrete pores are filled with the erosion product, there is an increase of approximately 10% in the concrete compressive strength and dynamic elastic modulus; and the concrete compressive strength is more sensitive to the stray current electrification period than the current intensity.

Keywords

stray current / sulfate attack / concrete damage / deterioration mechanism / degradation law

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