减缩材料对特细砂泵送混凝土干燥收缩的影响

Effect of shrinkage-reducing material on drying shrinkage of ultra-fine sand pumping concrete

通过混凝土干缩试验,研究了粉煤灰、聚丙烯纤维和膨胀剂等3种常见减缩材料对特细砂泵送混凝土不同龄期干燥收缩的影响。试验结果表明：分别掺加粉煤灰、聚丙烯纤维和膨胀剂均能不同程度地降低特细砂泵送混凝土的干缩率,且降低作用随着掺量增加、龄期增长而增大。粉煤灰能延缓干燥收缩的发展,在60~90 d龄期内降低作用明显;聚丙烯纤维掺量在0.8 kg/m^3时对干燥收缩影响效力最大;膨胀剂通过早期膨胀补偿抑制了干燥收缩,且其效果在湿度较大环境下更好。

Through the concrete drying shrinkage test,effects of fly ash,polypropylene fiber and expansion agent on drying shrinkage of ultra-fine sand pumping concrete at different ages were studied.The results show that,fly ash,polypropylene fiber and expansion agent can reduce drying shrinkage rate of ultra-fine sand pumping concrete in varying degrees,and the effects grow with concrete age and mixing amount of shrinkage-reducing materials.The fly ash can delay the development of drying shrinkage,and shows the strongest effect in the 60~90 d age;polypropylene fiber shows the greatest impact on drying shrinkage when the mixing amount is 0.8 kg/m3;expansive agent inhibits drying shrinkage through the early expansion compensation,and has a greater effect in higher humidity environment.