常温养护条件下活性粉末混凝土抗硫酸盐侵蚀性能试验研究

Experimental study on resistance to sulfate attack of active powder concrete under normal temperature curing condition

通过常温养护条件下活性粉末混凝土力学性能试验,优选3组配合比进行硫酸盐干湿循环侵蚀试验,从质量和抗压强度两个方面分析活性粉末混凝土的损伤劣化程度。试验结果表明:随着干湿循环时间的增加,活性粉末混凝土的质量和抗压强度损失率均呈现先缓慢增长后缓慢降低的趋势;同时,掺入适量的粉煤灰和硅灰,可以较好的发挥二次反应,改善试件的结构性能,提高试件密实度,增强抗侵蚀性能。配合比最优的一组活性粉末混凝土,质量损失率由-1.5%到0.2%,抗压强度损失率由-1.0%到3.3%,其质量和抗压强度损失率都较为理想,前期出现质量和抗压强度不减而增的现象,后期虽有减小但是很微弱。在饱和硫酸钠溶液的侵蚀活性粉末混凝土的基础上建立腐蚀损伤模型,即试件的抗压强度损失率与侵蚀介质浓度和侵蚀时间成正比,计算和试验结果基本吻合。

Through the mechanical property test of reactive powder concrete under the condition of normal temperature curing,three groups of mix proportion were selected to carry out the sulfate dry wet cyclic erosion test,and the damage and degradation degree of reactive powder concrete was analyzed from two aspects of quality and compressive strength.The test results show that with the increase of dry and wet cycle time,the quality and compressive strength loss rate of reactive powder concrete show a trend of slow growth first and then slow reduction.At the same time,adding a proper amount of fly ash and silica fume can give full play to the secondary reaction,improve the structural performance of the specimen,improve the compactness of the specimen,and increase the erosion resistance.The group of reactive powder concrete with the best mix proportion,the loss rate of mass is from-1.5%to 0.2%,the loss rate of compressive strength is from-1.0%to 3.3%,the loss rate of mass and compressive strength are both ideal,the phenomenon that the mass and compressive strength increase in the early stage and decrease in the later stage is very weak.Based on the erosion of reactive powder concrete by saturated sodium sulfate solution,a corrosion damage model is established,which means that the loss rate of compressive strength of the specimen is directly proportional to the concentration of the erosion medium and the erosion time,and the calculation results are basically consistent with the test results.