补偿收缩混凝土的自收缩特性

AUTOGENOUS SHRINKAGE OF SHRINKAGE-COMPENSATING CONCRETE

通过对比掺与不掺膨胀剂的混凝土的早期自收缩及其胶凝材料体系的水化热和化学结合水量发展规律,研究了膨胀剂对低水胶比混凝土自收缩的补偿作用效果。结果表明:8%掺量(质量分数)的钙矾石系膨胀剂(U型)对硅酸盐水泥混凝土和粉煤灰混凝土的自收缩有一定程度的补偿效果,而对矿渣混凝土的自收缩没有补偿。在较早期,膨胀剂促进复合胶凝材料的水化,在后期,膨胀剂也促进了矿渣–水泥体系的水化,其总放热量和化学结合水量均高于未掺膨胀剂的,但抑制了硅酸盐水泥和粉煤灰–水泥体系的正常水化,使其水化放热速率降低,总放热量和化学结合水量减小。

The compensation effect of calcium sulfoaluminate based-expansive agent on autogenous shrinkage of three types of concrete containing different binders prepared with/without fly ash or slag were studied.The heat of hydration and non-evaporable water content of various binders were also examined.The results show that hydration reactions in all pastes are enhanced at early ages（the first two days of hydration） and reduced except slag cement pastes at late ages when expansive agent is added.It also indicates that expansive agent with 8%（in mass） dosage has compensation effect to some extent for autogenous shrinkage of ordinary Portland cement concrete and fly ash concrete;but enhances autogenous shrinkage of slag concrete.