2017 Volume 71 Issue 1 Pages 353-360
Nowadays, there is necessity to consider the degradation phenomena of concrete with sulfate derived from groundwater and underground soil in relation to long-term durability of concrete structure, and material design for the sulfate resistance is required. Also, as sulfate deterioration changes hydrate and pore structure generated by reaction between sulfate ion and cement hydrate every moment, it is indispensable to consider mass transfer behavior in evaluating long-term durability. On the other hand, there is a need for effective use of industrial by-products. Therefore, the purpose of this research is to evaluate the effect of hardened cementitious materials using CaO-MgO-SiO2-based materials from industrial by-products with autoclave curing to the sulfate resistance, and to clarify the mechanism of sulfate resistance from the view point of the changes in hydration products and pore structure including secondary products after sulfate entry on the material transfer property. As a result, the generation of tobermorite and calcium magnesium silicate hydrate having Si-O bonds equivalent of and tobermorite could possibly contribute to the sulfate resistance. Furthermore, unreacted akermanite and C-S-H remaining in the cured body reacted with the sulfate, and the formation of secondary hydrate such as silica gel with high degree of polymerization resulted in complicated pore structure and suppression of material transfer properties.'
