【摘要】 前文报道了对CaO-SiO₂混合物经水热处理和低温烧成制备活性β-C₂S,本文则对其形成机理作进一步探讨。本文用化学分析法测定了经不同时间蒸养的物料中的fCaO和未结合的SiO₂。对形成的水化硅酸钙经三甲基硅烷化（TMs）反应,并用气相色谱（GLC）及凝胶渗透色谱（GPC）分离和测定TMS衍生物.发现在蒸养物枓中除有单硅酸和二硅酸化合物外,还有相当数量的多聚硅酸阴离子,其中主要的相是四聚硅酸（包括坏状和链状）阴离子团。GPC检测到的最大分子量为11000。蒸养料经823K、1023K和1223K煅烧后,单硅酸化合物增多,多聚硅酸化合物量相应减少,且明显出现三硅酸化合物。作者据上述结果初步认为,经水热合成处理后再煅烧得到的活性β-C₂S是经多聚硅酸化合物或至少有部分C₂S是经多聚硅酸化合物过渡而形成,这与通常公认的C₂S直接形成机理有所不同。更多还原

【Abstract】 An active β-C₂S, synthesised under hydrothermal treatment by using a CaO-SiO₂ mixture and then sintered at low temperature, has been reported in a previous paper. In this paper the formation mechanism of active β-C₂S is studied. The amounts of fCaO and unreacted SiO₂ in the mixture after hydrothermal treatment for various periods are determined by chemical analysis. Trimethylsilyl derivatives of calcium silicate hydrates formed in the mixture are separated by gas-liquid chromatography （OLC） and gel permeation chromatography（GPC）. It is found that, in addition to monomer anddimer, there is also a significant quantity of polymer in the mixtures. The measured molecular weight of the TMS derivatives is about 11000, and the major phase identified by GPC is tetramer（including both cyclic and chain forms）. After sintering at 823K, 1023K and 1223K, the amount of monomer increases with temperature, and meanwhile, the amount of polysilicates decreases. The trimer also appears in the mixture in an appreciable amount. From these, it appears that the formation mechanism of active β-C₂S, is somewhat different from the prevailing solid-state reaction mechanism, i.e. β-C₂S at least part of β-C₂S is derived from intermediate products——polysilicate hydrates, but is not formed immediately from the hydrate.更多还原