高性能混凝土的自收缩机理研究

SELF-DESICCATION MECHANISMS OF HIGH-PERFORMANCE CONCRETE

主要研究了水灰比m (w) /m (c)和硅灰对高性能混凝土(HPC)自收缩率和内部湿度的影响 ,并对自收缩机理进行了理论探讨 .结果表明 :混凝土自收缩率随着m(w) /m(c)的降低而增加 ,但内部湿度随之降低 ;在相同m (w ) /m (c)下 ,掺入硅灰将明显使HPC的自收缩率增加和内部湿度降低 .理论分析表明 ,混凝土中可溶离子浓度的增大 ,及凝胶孔水、吸附水、层间水在总可蒸发水量中的比例增大是导致HPC自收缩或自干燥的主要机理 .

Effects of m（w）/m（c） ratio and silica fume on the autogenous shrinkage and internal relative humidity of high performance concrete (HPC) were mainly investigated. Self_desiccation mechanisms of HPC were also analysed. Results show that the autogenous shrinkage and internal relative humidity of HPC increase and decrease respectively with the reduction of m（w）/m（c）. The effects are amplified by the addition of silica fume. Theoretical analyses indicate that the reduction of internal relative humidity or so_called self_desiccation of HPC may be mainly caused by the increase in the mole concentration of soluble ions in HPC and the fractions of gel water, absorbed water and interlayer water in the total amount of evaporable water.