预拌干料贮存期对补偿收缩混凝土抗拉强度的影响

预拌干料是一种将混凝土的原材料——水泥、砂子、石子在不加水的情况下按设计配合比拌合均匀、贮存的混合料,使用时掺加膨胀剂和水制成预拌补偿收缩混凝土。对预拌干料贮存不同时间、不同膨胀剂掺量的预拌补偿收缩混凝土进行劈裂抗拉试验,研究结果表明,膨胀剂掺量为6%时,预拌补偿收缩混凝土抗拉强度较大;随着贮存期延长,预拌补偿收缩混凝土抗拉强度不断降低,近似呈指数函数下降趋势,在贮存期10 d内降低程度较大;相同贮存期条件下,膨胀剂为6%的预拌补偿收缩混凝土抗拉强度损失率低于普通混凝土的,掺入适量的膨胀剂能够起到密实混凝土以及减少混凝土抗拉强度损失的作用。

Influence of Storage Period for Dry-mixed Materials on Tensile Strength of Shrinkage-compensating Concrete

Dry-mixed materials are mixture that is made by blending cement, sand and gravel uniformly in design proportion without adding water and store in bags. Use dry-mixed materials to produce ready-mixed shrinkage-compensating concrete by adding expansive agent and water. The splitting tensile test of ready-mixed shrinkage-compensating concrete with different dosages of expansive agent and different storage periods was conducted. The results show that the tensile strength of ready-mixed shrinkage-compensating concrete with 6% expansive agent addition is higher. The tensile strength of ready-mixed shrinkage-compensating concrete with 6% expansive agent declines similarly in an exponential function with the prolong of the storage period. Compared with 0% dosages of expansive agent, the tensile strength loss rate is lower when dosages of expansive agent is 6%, adding proper dosages of expansive agent can improve the densification of concrete and reduce tensile strength loss of concrete.