MgO混凝土自生体积变形影响因素分析

自生体积变形是MgO混凝土在工程应用中最重要的性能之一。系统研究了MgO膨胀剂品种和掺量、水泥品种、骨料种类、粉煤灰掺量等原材料以及水胶比对龄期长达1 400 d的MgO混凝土自生体积变形性能的影响。结果表明：掺入4%～6%、活性反应时间为50～200 s的MgO膨胀剂后，混凝土的自生体积变形经过2 a左右逐渐趋于稳定，无倒缩或不收敛现象；水泥中MgO含量并不能真实反映产生有效膨胀的方镁石含量；骨料长期吸水率与MgO混凝土的自生体积变形存在着良好的对应关系，骨料吸水率越高，其MgO混凝土自生体积膨胀变形越小。

Analysis of influential factors on autogenous volume deformation of MgO concrete

The autogenous volume deformation is one of the most important performances of MgO concrete. The influences of MgO expansion agent types and amount, cement types, aggregates types as well as the fly ash amount on autogenous volume deformation of MgO concrete with 1400d curing age were systematically investigated. The research results indicated that the autogenous volume deformation tended to stable in approximately 2 years without retraction when 4% to 6% of MgO with reactivity time ranging from 50s to 200s was doped. The MgO content in cement concrete cannot accurately reflect the periclase content that generates effective expansion. The autogenous volume deformation and long-term water absorption of aggregates are correlated well, namely the autogenous volume decreased with the increase of water absorption of aggregates. 