Molecular modeling and experimental of rubber-based ultra-high-performance concrete

The preparation of concrete by replacing aggregates with waste rubber particles after simple pretreatment is an efficient and environmentally friendly way. However, a large number of studies have shown that the introduction of rubber aggregates can significantly degrade the mechanical properties of concrete. In this paper, silane coupling agent-modified rubber is incorporated into ultra-high-performance concrete (UHPC) materials, and the effectiveness of SCA in bridging rubber and UHPC was confirmed. It was confirmed that the modified treated rubber did not introduce a new hydration phase by X-Ray Diffraction. At a molecular scale, SCA molecules can penetrate into the rubber group, forming a physical barrier between the matrix and the rubber. The SCA modification of 50% and 100% silica interfaces can increase the shear strength by 58.5% and 24.4%, respectively. And the shear strength of C-S-H modified by SCA can be increased by 96.6%. In the experiment, the flexural strength of rubber-based UHPC can be increased by 12.3% at 2.5% concentration of SCA. Therefore, the rubber powder is expected to be incorporated into the UHPC system through further mix ratio design.