硬化混凝土气孔参数的研究  

On Better Understanding of Effect of Air VoidParameters on Freeze-Thaw Durability of Concrete

作　　者：张德思[1] 成秀珍[1] 

机构地区：[1]西北工业大学建筑材料科学研究所,陕西西安710072

出　　处：《西北工业大学学报》2002年第1期10-13,共4页Journal of Northwestern Polytechnical University

基　　金：国家自然科学基金(59879024)资助

摘　　要：通过试验研究，采用显微计数观测法测定了硬化混凝土的含气量、气孔比表面积、气泡间距指数等气孔参数。探讨了气孔参数、强度等级、引气量水平、水灰比等因素对普通混凝土和粉煤灰混凝土抗冻融耐久性的影响。研究指出，硬化混凝土中的实际含气量和新拌混凝土引气量线性相关。气泡间距指数随引气量的增加而减小。气孔的比表面积随引气量的变化而变化。硬化混凝土中的实际含气量、气泡间距指数和抗压强度是影响混凝土抗冻性的决定性因素。Abstract: Previous studies on effect of air void parameters on freeze-thaw durability of concrete are, in our opinion , quite unsystematic and deficient in specific information provided. The air void parameters we studied were air void content, specific surface area and spacing factor and we used microscopical examination method to measure them. We explain in section 2 in much detail. The experiments we carried out and the results we obtained are shown in Figs. 1 through 4. These results suggest to us three conclusions. (1) There is a linear relationship between the measurements of air content in the fresh state and the air void content in the hardened state. The specific surface area varies with air content. The spacing factor decreases with increasing air content. The air content, spacing factor and strength of the concrete affect significantly the freeze-thaw durability of concrete with and without PFA. (2) Required air content limits for frost resistant concrete depend on the grade of the concrete specified. The minimum air content and maximum water/cement ratio required by ACI 318 for freeze-thaw resistant concrete and the upper limit of 0. 25 mm for the spacing factor recommended by Powers may be too restrictive. (3) For concrete in the strength range of C20 to C50, an air content of 3. 5 % and a spacing factor less than 0. 45~ 0. 55mm can ensure a freeze/thaw durability factor above 90 %.

关 键 词：硬化混凝土 引气量 含气量 气泡间距指数 抗冻性 气孔参数 抗压强度 

分 类 号：TU528.45[建筑科学—建筑技术科学]