Acceleration of cement hydration with synthetic calcium silicate hydrates II - Mechanism of action and significance for alternative binders

波特兰水泥基粘结剂是目前地球上使用最多的合成材料。因此，水泥行业承担了大约8%的人为二氧化碳排放。此外，该行业正在发展壮大。复合水泥中熟料份额的减少会导致反应动力学变慢，这必须由有效的促进剂来补偿。项目“合成水化硅酸钙加速水泥水化II-机理及其对替代粘结剂的影响”旨在将C-S-H播种这一有前途的概念应用于其他SCM和粘结剂。在第一步中，应对该机制有更深入的了解。人工C-S-H对水泥水化的加速作用通常归因于水泥外表面水化产物的成核。然而，这一假设缺乏明确的证据。此外，还需要关于种子和产品相互作用的额外信息，以便对单个种子材料进行量身定制的合成。第一个目标应通过研究特性良好的混凝土外加剂与水泥中的C-S-H种子的相互作用来间接实现。此外，还应通过分离反应环境和原位方法来研究种子和粘结剂的直接相互作用。先前项目中进行的原位红外研究被证明是非常有前景的，并提供了关于C-S-H合成过程的有价值的信息。作为拟议项目的一部分，该方法现在将适用于整个活页夹系统。这项工作还通过对水合过程进行建模来补充。根据结果，将对C-S-H种子进行靶向修饰，以揭示该方法的全部潜力。为此，将寻求一种无机方法，其中产生晶态C-S-H相，或者在非晶态C-S-H的结构中加入外来原子。一方面，用混凝土外加剂制备有机复合材料以获得多功能外加剂；另一方面，与聚合物的相互作用有待于研究，因为聚合物对矿物形态的影响是已知的。前两个工作包的结果将结合在一起，以实现最后一个目标--使该方法适应替代粘合剂。首先，分析反应产物为水化硅酸钙的粘结剂，如波特兰水泥中的粘结剂。最后，具有不同水化产物的粘结剂，如铝酸钙水泥，应通过量身定制的形核种子来激活。

Portland cement-based binders are currently the most used synthetic material on earth. As a result, the cement industry is responsible for about 8% of the anthropogenic CO2 emissions. Moreover, the industry is growing. A reduction of the clinker share in composite cements results in a slower reaction kinetics which must be compensated by effective accelerators. The project "Acceleration of cement hydration with synthetic calcium silicate hydrates II - mechanism and implications for alternative binders" aims to adapt the promising concept of C-S-H seeding to other SCMs and binders. In a first step, a deeper understanding of the mechanism shall be obtained. The acceleration of cement hydration by artificial C-S-H is commonly attributed to the nucleation of hydration products on the extra surface. However, clear evidence for this assumption is missing. Moreover, additional information about seed and product interaction is needed for a tailored synthesis of individual seeding materials. This first goal shall be achieved indirectly by investigating the interaction of well-characterized concrete additives with C-S-H seeds in cement. Moreover, the direct interaction of seed and binder shall be investigated by separating the reaction environment and in-situ methods. In-situ infrared studies conducted in the previous project proved to be very promising and provided valuable information on the reaction process during C-S-H synthesis. The method is now to be adapted to the entire binder system as part of the proposed project. The work is supplemented by modelling the hydration process. Based on the results, targeted modifications of the C-S-H seed will be investigated to reveal the full potential of the method. To this end, an inorganic approach will be pursued in which crystalline C-S-H phases are produced, or foreign atoms are incorporated into the structure of the amorphous C-S-H. On the one hand, organic composites are to be produced with concrete admixtures to obtain multifunctional additives; on the other hand, the interaction with polymers, whose influence on the morphology of minerals is known, is to be investigated. The results from the first two work packages will be combined to achieve the last objective - adapting the method to alternative binders. Initially, binders whose reaction product is calcium silicate hydrate, as in Portland cement, will be analyzed. Finally, binders with different hydration products such as calcium aluminate cement shall be activated by tailored nucleation seeds.