The interface properties between hydrated cement paste (hcp) and aggregates largely determine the various performances of concrete. In this work, molecular dynamics simulations were employed to explore the atomistic interaction mechanisms between the commonly used aggregate phase calcite/silica and calcium silicate hydrates (C-S-H), as well as the effect of moisture. The results suggest that the C-S-H/calcite interface is relatively strong and stable under both dry and moist conditions, which is caused by the high-strength interfacial connections formed between calcium ions from calcite and high-polarity non-bridging oxygen atoms from the C-S-H surface. Silica can be also adsorbed on the dry C-S-H surface by the H-bonds; however, the presence of water molecules on the interface may substantially decrease the affinities. Furthermore, the dynamics interface separation tests of C-S-H/aggregates were also implemented by molecular dynamics. The shape of the calculated stress-separation distance curves obeys the quasi-static cohesive law obtained experimentally. The moisture conditions and strain rates were found to affect the separation process of C-S-H/silica. A wetter interface and smaller loading rate may lead to a lower adhesion strength. The mechanisms interpreted here may shed new lights on the understandings of hcp/aggregate interactions at a nano-length scale and creation of high performance cementitious materials.

水合水泥浆（hcp）与集料之间的界面性质在很大程度上决定了混凝土的各种性能。在这项工作中，使用分子动力学模拟来探索常用的聚集相方解石/二氧化硅与硅酸钙水合物（CSH）之间的原子相互作用机理，以及水分的影响。结果表明，CSH /方解石界面在干燥和潮湿条件下均相对牢固且稳定，这是由于方解石的钙离子与CSH表面的高极性非桥接氧原子之间形成了高强度界面连接所致。二氧化硅还可以通过氢键吸附在干燥的CSH表面上。然而，界面上水分子的存在可能会大大降低亲和力。此外，CSH /聚集体的动力学界面分离测试也通过分子动力学进行。计算出的应力-分离距离曲线的形状服从实验获得的准静态内聚定律。发现水分条件和应变速率会影响CSH /二氧化硅的分离过程。较湿的界面和较小的加载速率可能导致较低的粘合强度。此处解释的机制可能会为纳米级hcp /聚集体相互作用以及高性能胶凝材料的创建提供新的思路。发现水分条件和应变速率会影响CSH /二氧化硅的分离过程。较湿的界面和较小的加载速率可能导致较低的粘合强度。此处解释的机制可能会为纳米级hcp /聚集体相互作用以及高性能胶凝材料的创建提供新的思路。发现水分条件和应变速率会影响CSH /二氧化硅的分离过程。较湿的界面和较小的加载速率可能导致较低的粘合强度。此处解释的机制可能会为纳米级hcp /聚集体相互作用以及高性能胶凝材料的创建提供新的思路。