预湿砂浆颗粒对高强混凝土早期自收缩的影响

Influence of pre-wetted mortar particles on the early-aged autogenous shrinkage of high-strength concrete

使用水灰比为0.5的早龄期砂浆颗粒对高强混凝土实施了内养护,研究了预湿砂浆颗粒对高强混凝土早期自收缩、抗压强度和显微结构的影响。结果表明:预湿砂浆颗粒可降低高强混凝土早期自收缩,掺量越大,减缩效果越显著,且适当的掺量对抗压强度影响较小;预湿砂浆颗粒掺量为12%时,可降低平均自收缩46.6%,而28 d强度仅降低6.7%;预湿砂浆颗粒是一种活性内养护载体,在混凝土中会继续水化,可改善水泥孔隙结构,提高界面密实性。

Early-age pro-wetted mortar particles with W/C of 0.5 were used as internal curing agent to investigate the influence on the early-age autogenuus shiinkage,compressive strength and micrastructure of high-strength concrete. Results showed that mortar particles as internal curing agent could mitigate the autogenous shrinkage of high-strength concrete, higher amount of added pro-wetted mortar particles could lead to more reduction of autogenous shrinkage. Proper amount of pro-wetted mortar particles would not significantly reduce the compressive strength,and 12% substitution ratio of sand by mortar particles could reduce 46.6% of the average autagenons shrinkage, which led to a reduction of＂ the 28 day compressive strength at only 6.7%. Mortar particles are reactive internal curing agent,which allows further hydration reaction within concrete,thus,refining the porosity and＂ strengthening the microstmcture of cement paste surrounding mortar particles.