Effects of annealing on crystal structure and hydraulic reactivity of alite doped with MgO were studied. Crystal structure of alite was analyzed by X-ray diffraction (XRD) and transmission electron microscopy (TEM).The hydraulic properties were presented by isothermal calorimetric. The results showed that T2, T3 and M3 modifications were obtained at room temperature while the dosages of MgO were 0. 5% ,1. 0% and 2. 0% , respectively. Samples doped with 0. 5% and 1. 0% MgO were remained as T2 and T3 modifications. Meanwhile,the reactivity of alite was reduced,thus resulting in a low 48 h cumulative heat of hydration. The polymorph of sample doped with 2. 0% MgO transformed from monoclinic to triclinic while annealed at 1 100 ℃ for 3 h or at 1 200 ℃ for 1 and 3 h,respectively. Many defects and strains were produced in the process of polymorph transformation, and consequently the hydraulic reactivity increased. Meanwhile, the process of polymorph transformation was a dynamics process and closely related to the time and temperature of annealing.%实验研究热处理过程对MgO掺杂阿利特的晶型与水化性能的影响,采用X线衍射仪(XRD)和透射电子显微镜(TEM)表征样品晶体结构变化,并测试其水化活性.结果表明:当MgO掺量为0.5％、1.0％和2.0％时,室温下样品稳定的晶型分别为T2、T3和M3型.MgO掺量为0.5％与1.0％的阿利特,热处理对样品晶型几乎没有影响,仍为T2和T3型,而热处理使样品水化活性降低,48 h累积水化放热量下降.MgO掺量为2.0％时,当样品在1100℃下热处理3h或1200℃下热处理1、3h后,晶型均发生明显转变,由单斜型转变为三斜型.由于晶型转变,阿利特产生大量的缺陷和应力,水化活性显著提高.另外,阿利特晶型的转变是一个动力学过程,与温度和时间紧密相关.
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