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为了测定水泥基材料的早龄期热膨胀系数,并揭示和把握其时变特征、影响因素,通过自行设计的实验方法抑制早龄期胶凝材料的水化和自收缩的发生,获得水泥砂浆的单纯温度变形随测试温度变化的规律,从而求得热膨胀系数,进而以水化龄期为参数获得热膨胀系数的时间依存特征。结果表明:以–2～3℃作为测试变温区间能有效抑制水泥的水化进程和自收缩,从而获得砂浆的单纯温度变形;砂浆的早龄期热膨胀系数随龄期增加的变化表现为急剧下降、缓慢回升和持续稳定3个基本阶段;随着水泥用量的减少和水灰比的提高,砂浆的热膨胀系数特征值(最大值、最小值和稳定值)增大。
In order to determine the coefficient of thermal expansion of cement-based materials at early age and to reveal and grasp the time-varying characteristics and influencing factors, the hydration and self-shrinkage of early-age gelling materials were restrained by self-designed experimental methods. According to the law of temperature change, the coefficient of thermal expansion was calculated, and then the time dependent characteristics of thermal expansion coefficient were obtained by hydration age. The results show that the temperature change of -2 ~ 3 ℃ can effectively suppress the hydration process and self-shrinkage of the cement, so as to obtain the pure temperature deformation of the mortar. The change of the early age thermal expansion coefficient of the mortar shows a sharp decline with age , Slow recovery and steady three basic stages. With the decrease of cement consumption and the increase of water-cement ratio, the eigenvalues (maximum, minimum and steady value) of the thermal expansion coefficient of mortar increase.