Research on the Sulfate-resistant Chemical Attack Mechanism of Concrete with Mineral Admixture

Abstract

Abstract Durability is the most important factor for evaluating the service life of concrete, and the chemical attack of sulfate is an important factor affecting the durability of concrete. In this paper, fly ash, slag, metakaolin and silica fume were used as mineral admixtures to explore their impact on sulfate chemical attack, and the chemical attack mechanism of sulphate was deeply analyzed, the results showed that: the incorporation of fly ash, slag, and silica fume effectively improves the sulfate-resistant chemical attack capacity of concrete. The concrete was chemically attacked 30d in sulfate solution, which will increased its compressive strength and quality, it was mainly due to the secondary hydration reaction of fly ash and slag, part Ca (OH)2 reacted with Na2SO4 solution to generate gypsum and ettringite, and made the internal structure of concrete more compact. As the age of sulfate chemical attack increases, the ettringite expands with water, and causes concrete to be expanded or peeled. Silica fume mainly provides more active SiO2 for the secondary hydration reaction, consumes more Ca (OH)2, and reduces the formation of ettringite.