摘要
本文用热重分析(TGA)及其微分(DTG)定量测定β-C_2S各龄期水化试样中的结合水量,并区分出不同状态的结合水,由此揭示出β-C_2S水化产物包括:300℃以下脱水的水化硅酸钙(C-S-H)凝胶;300～420℃左右脱水的类似C_2SH(A)的水化硅酸钙;450℃左右脱水的Ca(OH)_2;还有一个850℃左右脱水的水化硅酸钙相。将TGA与前文所述的QXRD方法相结合,就能定量地求出各龄期β-C_2S的水化程度,Ca(OH)_2含量、水化硅酸钙总量与平均组成、以及β-C_2S的水化速度。实例测定表明:B_2O_3稳定的β-C_2S水化速度高于Ca_3(PO_4)_2稳定的β-C_2S。后者在60天之内水化速度几乎相同,类似于一级化学反应控制的过程,水化硅酸钙平均组成为C_(1.75-1.80)SH_(2.20-2.35);前者的水化还受到扩散控制,水化硅酸钙平均组成为C_(1.70-1.75)SH_(2.2-2.4)。β-C_2S的结晶度、密度及晶粒尺寸的差别是造成QXRD定量分析回归方程及水化活性差异的可能原因。
The amount of fixed water in hydrated β-C_2S was determined by TGA and its combination states were distinguished by DTG. It was shown that. β-C_2S hydration products include C-S-H losing water below 300C, a gel similar to C_2SH(A) dehydrating between 300℃ and 420℃, Ca(OH)_2, and another gel losing weight around 850℃. By combining the results of TGA and DTG with that of QXRD mentioned in prresious paper, β-C_2S hydration extents, the contents of Ca(OH)_2, the total amount and average composition of gels at variors peri- ods, and the hydration speed of β-C_2S can be calculated. A practical application of this method indicated that the hydration speed of β-C_2 S doped with B_2O_3is higher than that with Ca_3(PO_4)_2 and the total gels from them have average formula C_(1.75-1.75)SH_(2.2-2.4) and C_(1.75-1.80) SH_(2.20-2.35) respectively. The later is controlled by chemical reaction while the former is contoled by both diffusion and chemical reaction. These differences may be caused by the differences in crystallinity. density, and crystal size of the two kinds of β-C_2 S.
出处
《中国建材科技》
1991年第3期32-41,共10页
China Building Materials Science & Technology
