Molecular dynamics simulation of interfacial mechanical properties of crumb rubber concrete

Abstract

Crumb rubber concrete is a new type of cement concrete made from waste rubber as partial aggregate. The mechanical properties and resistance to cracking of crumb rubber concrete are not only related to the mechanical properties of each constituent phase, but also closely related to the interface characteristics and interactions between the cement paste and rubber/aggregate. This article uses molecular dynamics simulation to analyze the two characteristic interfaces (coarse aggregate/cement paste, rubber/cement paste) in the micro and nano structures of crumb rubber concrete at the molecular scale. By simulating the indentation process, interfacial adhesion energy, and interfacial pull-out performance, the micro mechanical properties and mechanisms of different interfaces were further compared and analyzed. From the simulation results, it can be seen that the C-S-H/calcite interface is mainly composed of ion bonds, with the highest interaction force. The C-S-H/silica interface is mainly composed of hydrogen bonds, while the C-S-H/rubber interface is mainly composed of van der Waals force, with the lowest interaction force. The C-S-H/calcite interface has the highest adhesion energy, while the C-S-H/rubber interface has the lowest adhesion energy. In interface indentation simulation, calcite has the greatest impact on C-S-H, while rubber has the smallest impact on C-S-H.