Abstract
Sulfate attack is known as one of the deterioration phenomena of concrete structures. Sulfates react chemically with hydration products of cement pastes and lead expansion or weakening of cement matrix. Deterioration cases of this phenomenon have been reported in a variety of environments all over the world. However, most of studies about sulfate resistance of hardened cementitious materials were mainly considered at 23℃ in Na2SO4 solution immersion. Thus, this study was conducted to investigate the effect of sulfate species（Na2SO4 and MgSO4）and high temperature（40℃）on the mechanisms of sulfate attack of cementitious materials containing Ordinary Portland Cement（OPC）with Blast Furnace Slag（BFS）, Anhydrite（AH）and Limestone Powder（LSP）, and to evaluate the expansion characteristics of specimens immersed sulfate solutions considering “Amount of ettringite”, “Ettringite generation rate” and “Ettringite generation origin”.
From the results of sulfate immersion test, the expansion was caused due to Na2SO4, however not only expansion but also mass decrease were caused due to MgSO4. This was considered that hydration products in each sulfate solution were different because of pH differences of sulfate solutions were occurred by the difference of sulfate species. And the expansion characteristics of the specimens were not evaluated by only simple amount of ettringite, however it became able to evaluate considering the ettringite generation rate and ettringite generation origin. In addition, the paste specimen of 70％ BFS-cement with 10％ AH and 10％ LSP（BFS 59.5％-OPC 25.5％-AH 10％-LSP 10％）was proposed a material design against sulfate attack.
