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前文报道了对CaO-SiO_2混合物经水热处理和低温烧成制备活性β-C_2S,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SiO_2。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-C_2S是经多聚硅酸化合物或至少有部分C_2S是经多聚硅酸化合物过渡而形成,这与通常公认的C_2S直接形成机理有所不同。
The previous report reported the CaO-SiO 2 mixture by hydrothermal treatment and low temperature sintering preparation of active β-C 2 S, this paper on its formation mechanism for further discussion. In this paper, chemical analysis was used to determine the fCaO and unbound SiO 2 in the steam-cured materials at different times. The formed hydrated calcium silicate was trimethylsilylated (TMs) and the TMS derivatives were separated and determined by gas chromatography (GLC) and gel permeation chromatography (GPC) In addition to silicic acid and disilicate compounds, there is also a significant amount of polysilicic acid anions, with the major phases being tetrasilicic acid (both bad and chain) anionic groups. The maximum molecular weight detected by GPC was 11,000. After steaming at 823K, 1023K and 1223K, the amount of monosilicic acid compound increased, the amount of polysilicic acid compound decreased correspondingly, and trisilicate compounds appeared obviously. According to the above results, the author preliminarily believes that active β-C 2 S calcined after hydrothermal synthesis treatment is formed by polysilicic acid compound or at least some C 2 S transition through polysilicic acid compound, which is in agreement with commonly recognized C 2 S Direct formation mechanism is different.