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

Abstract：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.