Structural build-up in fresh cement paste at rest is characterized by time evolutions of storage modulus and yield stress, which both increase linearly in time during the induction period of hydration, followed by an exponential evolution after entering the acceleration period. Here, we investigate structural build-up by coupling calorimetry and oscillatory shear measurements of Portland Cement at different w/c ratios and in the absence of admixtures, capturing how the storage modulus evolves with changes in cumulative heat. This allows the decoupling of hydration kinetics from the mechanisms dictating build-up at rest. We obtain an exponential relation between stiffness and heat, with the same exponent in both the induction and acceleration periods. This suggests that, at least in the absence of admixtures, the same mechanism dictates build-up at rest in both periods. Since it is understood that C-S-H dictates build-up at rest in the acceleration period, we deduce that the same mechanism holds in the induction period.

中文翻译：

---

Portland Cement 的诱导期和加速期的静止结构堆积


新水泥浆体在静止状态下的结构堆积的特点是储能模量和屈服应力的时间演变，在水化诱导期均随时间线性增加，进入加速期后呈指数级演变。在这里，我们通过耦合量热法和振荡剪切测量来研究不同 w/c 比率和在没有外加剂的情况下波特兰水泥的结构堆积，捕捉储能模量如何随累积热量的变化而变化。这允许水合动力学与决定静息时堆积的机制解耦。我们得到了刚度和热量之间的指数关系，在诱导周期和加速周期中具有相同的指数。这表明，至少在没有外加剂的情况下，相同的机制决定了两个时期的静息堆积。既然可以理解 C-S-H 决定了加速期的静止积累，我们推断同样的机制在诱导期也成立。