The rheological properties of cement-based materials made with manufactured sand vary with the content and physio-chemical properties of microfines in the sand. However, the evaluation of rheological properties regarding the structural build-up at early-age hydration remains challenging for the cementitious materials prepared with different manufactured sands, due to complicated underlying structuration mechanisms. This paper studies the effect of disparate microfines of different manufactured sands on the non-linear growth of static yield stress of cement pastes at rest. The paste mixtures were prepared with 0.40 and 0.275 water-to-cement mass ratio (W/C) and had a fixed mini-slump flow of 240 ± 5 mm. Test results show that the additional microfines facilitate the rapid early increase of static yield stress over 10 min rest, due to the intensified flocculation between total solid particles and simultaneously the greater strengthening of the agglomerating network by rapid cement hydration. Besides, the microfines promote the exponential growth of static yield stress over 10 to 120 min rest, given the accelerated particle network densification by the continuous cement hydration. Qualitative approaches describing the enhancement of flocculation by rapid early hydrates and the particle network densification during the succeeding early-age hydration are proposed to evaluate the rapid increase and exponential growth of static yield stress, by taking into account the evolving ratio of solid particles to excess interstitial solutions and the degree of cement hydration.

中文翻译：

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机制砂的微细粒对水泥浆体非线性结构堆积影响的潜在机制


用机制砂制成的水泥基材料的流变特性随砂中微细粉的含量和物理化学特性而变化。然而，由于复杂的底层结构机制，对于用不同机制砂制备的胶凝材料来说，对早期水化结构堆积的流变性能评估仍然具有挑战性。本文研究了不同机制砂的不同微细粒对静止时水泥浆体静态屈服应力非线性增长的影响。浆料混合物的水灰质量比 （W/C） 为 0.40 和 0.275，固定的小坍落度流动为 240 ± 5 mm。试验结果表明，由于总固体颗粒之间的絮凝加剧，同时水泥快速水化对团聚网络的更大加强，额外的微细颗粒有利于在 10 min 静止期间静态屈服应力的快速早期增加。此外，鉴于连续水泥水化加速了颗粒网络致密化，微细颗粒促进了静态屈服应力在 10 至 120 min 静止期间的指数增长。通过考虑固体颗粒与过量间隙溶液的比率和水泥水化程度，提出了描述快速早期水合物增强絮凝和随后的早期水化过程中颗粒网络致密化的定性方法，以评估静态屈服应力的快速增加和指数增长。