锚具槽回填微膨胀自密实混凝土试验研究

Experimental Study on Backfilling Micro-expansive Self-compacting Concrete in Anchor Slot

为解决长距离引水隧道无黏结预应力结构锚具槽混凝土振捣不密实或发生较大塑形变形导致开裂脱空等问题,研究粉煤灰掺量、膨胀剂掺量和水胶比对强度、限制膨胀率等性能的影响,设计了微膨胀自密实混凝土,测定其自身体积变形和自收缩变化。结果表明:水胶比0.40,粉煤灰掺量25%,膨胀剂用量30kg/m^(3)时,28d抗弯拉强度和抗压强度分别为4.77,53.6MPa,抗渗等级大于W11,混凝土60d自身体积变形率为20×10^(-6),趋于基本稳定,90d干燥收缩率约为-460×10^(-6),应加强微膨胀自密实混凝土的保湿养护,延长保湿养护的时间,以利于膨胀剂性能的发挥。

In order to solve the problems of cracking and voiding caused by uncompacted vibration or large plastic deformation of concrete in anchorage slot of unbonded prestressed structure in long-distance diversion tunnel,the effects of fly ash content,expansive agent content and water-binder ratio on strength and limited expansion rate were studied.The micro-expansion self-compacting concrete was designed,and its free volume deformation and autogenous shrinkage were measured.The results show that when the water-binder ratio is 0.40,the content of fly ash is 25%,and the dosage of expansive agent is 30kg/m^(3),the 28d flexural tensile strength is 4.77MPa and the 28d compressive strength is 53.6MPa,respectively,and the impermeability grade is greater than W11.The autogenous volume deformation of concrete is 20×10^(-6)in 60d,which tends to be basically stable,and the drying shrinkage is about-460×10^(-6)in 90d.The moisturizing curing of micro-expansion self-compacting concrete should be strengthened,and the time of moisturizing curing should be prolonged to facilitate the performance of expansive agent.