高频振捣对混凝土抗冻性的影响

Effect of high-frequency vibration on concrete frost resistance

采用4种水利水电工程常用的引气剂,分别配制水胶比为0.40、0.45和0.55的二级配引气混凝土进行试验,测量高频振捣后混凝土含气量变化和抗冻性。结果表明,水胶比为0.40时,优质引气剂混凝土的抗冻性对高频振捣并不敏感;水胶比为0.45时,高频振捣60 s和90 s后混凝土的抗冻性明显下降;水胶比为0.55时,混凝土的抗冻性随高频振捣时间的延长迅速下降。同时,引气剂品质对混凝土的抗冻性有明显的影响。根据试验结果,给出了不同水胶比混凝土对高频振捣时间的要求,供施工参考。

Four kinds of air-entraining admixtures normally used in hydraulic projects are adopted in the experiment concerned, with which two-graded air-entraining concrete with water cement ratios （W/C） of 0. 40, 0. 45 and 0. 55 is made for measuring the change of the air content and the frost resistance of the concrete after high-frequency vibration. The result shows that at a W/C ratio of 0. 40, the frost resistance of the concrete made with high-quality air-entraining admixtures is not sensitive to the high-frequency vibration; at a W/C ratio of 0. 45, the frost resistance is obviously decreased at the vibration time of 60 s and 90 s; when W/C ratio is further increased to 0. 55, the frost resistance of the concrete is quickly dropped along with the increase of vibration time. At the same time, the quality of air-entraining admixture also has obvious effect on the frost resistance of concrete. Based on the test results, appropriate high-frequency vibration time for the concrete with different W/C ratios is proposed.