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中文摘要：
为了研究硫酸盐侵蚀后喷射混凝土表面损伤层厚度变化,采用干湿交替方法,对同配合比模筑混凝土、喷射混凝土及钢纤维喷射混凝土进行硫酸盐侵蚀,利用超声波平测法对试件表层声时进行测定,采用回归方法对试验数据进行拟合,得出试件损伤层厚度。结果表明：随着干湿交替次数增加,试件表层超声波波速降低,试件密实度下降,损伤层厚度增大,用损伤层厚度表征试件硫酸盐侵蚀具有较好相关性。而后对硫酸盐侵蚀后喷射混凝土微观结构进行分析,发现喷射混凝土硫酸盐侵蚀破坏方式从初期钙矾石破坏转变为后期钙矾石、石膏复合破坏,且钙矾石及石膏含量随着交替次数的增多而增加;同时,对交替150次喷射混凝土试件进行钻孔分层取粉,对其进行物相分析及热分析,随着深度增加,试件中钙矾石含量先增大后减小继而平稳,但石膏含量持续减小,深度大于12mm时石膏含量为0。
英文摘要：
In order to analyze the damage layer thickness of shotcrete after sulfate attack,sulfate attack experiment was done to the formwoking concrete and shotcrete with and without steel fiber,which all were the same mixture by drywet cycle method.Meanwhile,the surface sonic time of specimen was determined by ultrasound plane monitor method,and the curves of sonic time and ranging were fitted by regression method.The experimental results showed that with dry-wet cycles increased,the surface ultrasonic velocity and density of specimen decreased.However,the damage layer thickness rose.It had a good correlation to characterization sulfate attack of specimen for using damage layer thickness.Furthermore,the microstructure of shotcrete under sulfate attack was analyzed and the main erosion pattern of shotcrete turned from ettringite to ettringite-gypsum.Meanwhile,the content of ettringite and gypsum increased with dry-wet cycles adding.Simultaneously,the stratified powders which drilled from shotcrete under 150＇s dry-wet cycle were analyzed for mineral phase composition.With the dry-wet cycle raised,the amount of ettringite first increased and then decreased,and finally led to stable.However,the determination of gypsum decreased gradually and even to 0when the depth was more than 12 mm.
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