石灰石粉和粉煤灰对混凝土抗冻融性能的影响

Influence of limestone powder and fly ash on freezing-thawing resistance of concrete

为全面掌握石灰石粉和粉煤灰对混凝土抗冻融性能的影响,提高混凝土的应用技术水平,通过可蒸发水含量法和快冻法,结合扫描电镜(SEM)微观分析,研究了石灰石粉细度对混凝土抗冻融性能的影响以及粉煤灰的改善作用.实验结果表明,比表面积分别为382、627和883 m2/kg的石灰石粉对混凝土的抗冻融性能影响不大,均低于普通混凝土;掺量为10%的粉煤灰极大地改善了石灰石粉混凝土的抗冻融性能,并接近普通混凝土,表现出石灰石粉早期增强和粉煤灰后期活性的互补效应;继续增加粉煤灰掺量,急剧劣化了石灰石粉对混凝土的抗冻融性能,并低于单掺10%石灰石粉的混凝土.

In order to obtain the comprehensive understanding for the influence of limestone powder and fly ash on the freezing-thawing resistance of concrete as well as enhance the application technology level of concrete,the influence of limestone powder fineness on the freezing-thawing resistance of concrete and the modification effect of fly ash were studied based on both evaporable water content and rapid freezing methods combining with scanning electron microscope（SEM） micro-analysis.The experimental results indicate that limestone powder respectively with specific surface area of 382,627 and 883m2/kg has little effect on the freezing-thawing resistance of concrete,and its freezing-thawing resistance is lower than that of ordinary concrete.The freezing-thawing resistance of limestone powder concrete gets remarkably improved by fly ash with mixing content of 10%,and is close to that of ordinary concrete.In addition,the complementary effect exhibits as the early enhancement of limestone powder and the later activity of fly ash.When the mixing content of fly ash continuously increases,the improvement effect of limestone powder on the freezing-thawing resistance of concrete deteriorates sharply,and the freezing-thawing resistance is lower than that of concrete only mixed with 10% limestone powder.