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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。
In this paper, thermogravimetric analysis (TGA) and its differential (DTG) were used to quantitatively determine the amount of bound water in hydration samples of β-C 2 S in all ages, and different states of bound water were distinguished, thereby revealing β-C 2 S hydration products. Including: Hydrated calcium silicate (CSH) gel dehydrated below 300°C; hydrated calcium silicate similar to C_2SH(A) dehydrated from 300 to 420°C; Ca(OH)_2 dehydrated around 450°C; A hydrated calcium silicate phase dehydrated around 850°C. Combining TGA with the QXRD method described earlier, the degree of hydration of β-C 2 S, the content of Ca(OH) 2 , the total amount and the average composition of calcium silicate hydrate, and the β- C 2 S hydration rate. The experimental results show that the stable hydration rate of β-C_2S in B_2O_3 is higher than that of Ca_3(PO_4)_2 stable β-C_2S. The hydration rate of the latter is almost the same within 60 days, which is similar to that of the first-order chemical reaction control. The average composition of calcium silicate hydrate is C_(1.75-1.80)SH_(2.20-2.35); the hydration of the former is also affected by Diffusion control, the average composition of calcium silicate hydrate is C_(1.70-1.75) SH_(2.2-2.4). The difference in crystallinity, density, and crystallite size of β-C_2S is a possible cause of QXRD’s quantitative analysis of regression equations and differences in hydration activity.