【摘要】 测试了水胶比为0.10~0.16水泥净浆及水胶比为0.16~0.50混凝土的自收缩,分析了石灰石粉和龄期对超低水胶比水泥净浆自收缩的影响.结合水泥石孔结构与水化进程,探讨了超低水胶比水泥混凝土的自收缩机理.结果表明:当水胶比≤0.16时,水泥净浆自收缩随水胶比的降低而降低;当水胶比低于0.25时,混凝土自收缩随水胶比的减小而降低;当水胶比高于0.25时,混凝土自收缩随水胶比的降低而增加;当水胶比为0.25(临界水胶比)时,混凝土的自收缩最大;磨细石灰石粉可以很好抑制水泥净浆的自收缩;超低水胶比水泥净浆1 d龄期的自收缩可达到180 d龄期收缩值的50%以上;超低水胶比水泥混凝土的自收缩特性与水泥石中孔结构以及水化进程有关.更多还原

【Abstract】 Autogenous shrinkage of cement paste with water-binder ratio(m(W)/m(B))of 0.10-0.16,and of concrete with m(W)/m(B) of 0.16-0.50 were measured,respectively.Influences of limestone powder and age on autogenous shrinkage were studied.Mechanism for autogenous shrinkage of cement concrete with very low m(W)/m(B) was analyzed by studying the pore structure and hydration progress of hardened cement paste.The results show that the autogenous shrinkage of cement paste reduces with decrease of m(W)/m(B) in the case of m(W)/m(B)≤0.16,the autogenous shrinkage of concrete reduces with decrease of m(W)/m(B) when m(W)/m(B) is less than 0.25,but autogenous shrinkage of concrete increases with decrease of m(W)/m(B) when m(W)/m(B) is over 0.25.A critical(m(W)/m(B)) of 0.25 is observed in which autogenous shrinkage of concrete is biggest.Limestone powder is effective to restrain the autogenous shrinkage of cement paste.The autogenous shrinkage of cement paste at 1 d age is above 50% of shrinkage value at 180 d.It is also concluded that mechanism for autogenous shrinkage of cement concrete with very low m(W)/m(B) is related to pore structure and hydration progress of hardened cement paste.更多还原