The use of recycled concrete aggregates for new concrete production is an important avenue to increase the sustainability of concrete. While numerous studies have demonstrated the benefit of nanosilica on recycled aggregate concrete, a connection between the enhanced properties and the properties of the calcium-silicate-hydrates is unproven. Thus, we investigate how nanosilica modifies the distribution of calcium-silicate-hydrates in fine recycled concrete aggregate mortar. Using an interdisciplinary approach of nanomechanical testing, data science, and advanced chemical, microstructural and pore structure characterization, we find that 12 wt.% nanosilica results in a 30.8% increase in the combined relative amount of high-density and ultra-high-density C-S-H, 16.7% reduction in C-S-H gel porosity, 24.4% reduction in total porosity, and 3.9% increase in fracture toughness.

中文翻译：

---

胶体纳米二氧化硅促进细再生混凝土骨料砂浆中的高密度硅酸钙水合物

使用再生混凝土骨料生产新混凝土是提高混凝土可持续性的重要途径。虽然大量研究已经证明纳米二氧化硅对再生骨料混凝土的益处，但增强的性能与水合硅酸钙的性能之间的联系尚未得到证实。因此，我们研究了纳米二氧化硅如何改变细粒再生混凝土骨料砂浆中硅酸钙水合物的分布。使用纳米力学测试、数据科学以及先进化学、微观结构和孔隙结构表征的跨学科方法，我们发现 12 wt.% 的纳米二氧化硅可使高密度和超高密度的相对数量增加 30.8% CSH，CSH 凝胶孔隙率降低 16.7%，总孔隙率降低 24.4%，断裂韧性提高 3.9%。