含石膏骨料引起的混凝土内部硫酸盐侵蚀

Internal Sulfate Attack on Concrete Caused by Gypsum-Bearing Aggregates

采用XRD,SEM/EDS,BSEM/EDS,光学显微分析和显微硬度分析等测试方法对湖北十字垭隧道工程混凝土进行了分析.结果表明:混凝土部分粗骨料含有石膏,在粗骨料中石膏与砂浆界面过渡区生成了钙矾石和碳硫硅钙石,导致混凝土开裂、界面过渡区疏松多孔,混凝土内部受到硫酸盐侵蚀破坏.

Some concrete samples taken from Shiziya tunnel in Hubei province were analyzed by XRD, SEM/EDS, BSEM/EDS, optical microscope and micro-hardness device. It is shown that deterioration of concrete in the form of cracking, and decrease of cohesion and strength are caused by the internal sulfate attack caused by gypsum-bearing dolomite coarse aggregates. Ettringite and thaumasite are formed in the interface transition zone between gypsum in the coarse aggregate and mortars. Therefore, the structures of the interface transition zone and the matrix are loose and porous, the micro-hardness is reduced.