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对C_4A_3$-CaSO_4-CaO体系(CCC体系,C_4A_3$为4CaO·3Al_2O_3·SO_3)的膨胀机理进行探讨。X射线衍射谱、水化放热历程和封闭环境下的体积变化测试结果表明:CCC体系中CaO的水化活性显著大于其它两者,CaO在水化早期表现出剧烈的水化放热行为,并产生剧烈而短暂的膨胀;CCC体系水化的目标产物是氢氧化钙和钙矾石,但生成钙矾石不是产生宏观膨胀的充要条件,适宜的钙矾石生成位置可以使其在C4A3$颗粒表面,通过钙矾石生长过程中产生的颗粒互斥效应产生膨胀;钙矾石生成过程的膨胀机理,除了吸水肿胀和结晶生长外,还有孔隙形成机理。CCC体系中CaO和CaSO_4的存在有利于保障钙矾石的生成位置。使用CaO-SO_3~-Al_2O_3三元相图表征了CCC体系的组成与水化产物之间的关系,并给出了适宜组成的CCC体系在三元相图中的存在区域。
The expansion mechanism of C_4A_3 $ -CaSO_4-CaO system (CCC system, C_4A_3 $ 4CaO · 3Al_2O_3 · SO_3) was discussed. The results of XRD, hydration exothermic and volume change test in closed environment show that the hydration activity of CaO in CCC system is significantly greater than that of the other two. CaO shows intense hydration and exothermic behavior in the early hydration stage, And cause violent and transient expansion; the target product of hydration of CCC system is calcium hydroxide and ettringite, but the formation of ettringite is not necessary and sufficient for macroscopic expansion. Appropriate ettringite formation position can make it in C4A3 The particle surface is swollen by the mutual exclusion of particles produced during the growth of ettringite. The expansion mechanism of ettringite, in addition to water swelling and crystal growth, also has pore formation mechanism. The presence of CaO and CaSO 4 in the CCC system helps to ensure the formation of ettringite. The relationship between the composition of CCC system and the hydration products was characterized by using the ternary phase diagram of CaO-SO_3 ~ -Al_2O_3. The CCC system in the ternary phase diagram was also given.