Admixture driven Rheology and Carbonatization pathways of Recycled Concrete Fines (ARCTIC)

该提案涉及将碳化再生混凝土微粉作为未来的补充胶凝材料(SCM)的价态。这一新方法结合了许多可持续发展的方法，即回收、捕获二氧化碳和减少水泥熟料。因此，碳化水泥浆体(CCP)领域的研究对我们发达社会的未来具有重要意义(德国每年约有6000万吨建筑垃圾)。这一领域仍然很年轻，许多问题仍然悬而未决，例如关于CCP作为SCM的反应性、水化动力学、力学性能和耐久性。这项建议侧重于再生混凝土微粉在碳化过程中产生的非常大的表面积。这反过来又导致高用水量，从而导致低强度值和不令人满意的耐久性。在这里，我们建议研究通过化学添加剂或水热后处理来改变所产生的表面的策略。此外，以聚羧酸醚(PCE)为基础的高效减水剂也能显著减少水分，但迄今尚未与碳化混凝土细粉结合进行研究。因此，该项目将涉及以下主题：a)了解碳酸化产生的大表面积的来源，b)改变(特别是减少)这一表面积的策略，c)结合CCP开发PCE的结构-活性关系，并确定含有CCP的水泥体系中减水的最佳结构，作为新型SCM，d)了解新型SCM的反应性取决于其表面和所使用的PCE化学，以及最后，了解新型SCM对水泥水化的影响。

The proposal deals with the valorization of carbonated recycled concrete fines as future supplementary cemenititous material (SCM). This new approach combines many sustainability approaches, namely recycling, capture of carbon dioxide and cement clinker reduction. Hence, research in this field of carbonated cement pastes (cCP) is of great importance for the future of our developed society (construction waste amount to approx 60 million tons per year in Germany). The field is still young and many questions are open, e.g. concerning the reactivity of cCP as SCM, hydration kinetics, mechanical properties and durability. This proposal focuses on the very large surface area which is generated by the carbonation process of recycled concrete fines. This in turn leads to a high water demand and as a consequence to low strength values and unsatisfying durability. Here, we propose to study strategies to change the resulting surface by either chemical additives or hydrothermal post treatment. Additionally, superplasticizers based on polycarboxylate ethers (PCE) also can provide a significant water reduction but have not been studied in combination with carbonated concrete fines as of yet. Consequently, the project will deal with the following topics: a) Understanding the origin of the large surface area generated by carbonation, b) strategies of changing (especially reducing) this surface area, c) developing a structure-activity relationship for PCE in combination with cCP and identifying the best structures for water reduction in cement systems containing cCP as novel SCM, d) understanding the reactivity of the novel SCM depending on their surface and PCE chemistry used and finally, e) understanding the influence of the novel SCMs on cement hydration.