Sugars have been widely used as setting retarders due to their efficiency and low cost. At low levels, they delay the hardening of the cement paste, reducing the hydration rate of the cement paste, especially alite. Some studies, however, have observed an accelerating effect through rheological tests, depending on the additive content and the water to cement (w/c) ratio, among other factors. So far, there is no explanation of the reason for this phenomenon supported by solid evidence. In this context, this work investigates the effect of sucrose on the structure (through in situ XRD and isothermal induction calorimetry) and on the rheological behavior (stationary rotational rheometry) of cement pastes. The results show that sucrose acts as an efficient setting retarder at low concentrations, delaying the setting time of the pastes with the reduction of the alite hydration rate, and without significant changes in the yield stress evolution. At high concentrations, the hydration delay of alite is even longer, followed by an intense formation of ettringite, whose main precursor is the ferrite phase. The formation of needle-shaped crystals of ettringite is the reason behind the acceleration phenomenon.

由于糖的效率和成本低，糖已被广泛用作缓凝剂。在低水平时，它们会延迟水泥浆的硬化，降低水泥浆的水化率，尤其是阿利特。然而，一些研究已经通过流变测试观察到加速效果，这取决于添加剂含量和水与水泥 (w/c) 的比率等因素。到目前为止，还没有确凿证据支持这种现象的原因。在此背景下，这项工作研究了蔗糖对结构（通过原位XRD 和等温感应量热法）和流变行为的影响（固定旋转流变仪）水泥浆。结果表明，蔗糖在低浓度下作为一种有效的缓凝剂，随着阿利特水化速率的降低而延迟浆料的凝固时间，而屈服应力演化没有显着变化。在高浓度下，阿利特的水化延迟甚至更长，随后强烈形成钙矾石，其主要前体是铁素体相。钙矾石针状晶体的形成是加速现象背后的原因。