Research on multi-scale mechanical properties of environment-friendly high-damping concrete used for structural seismic mitigation

Ordinary concrete is difficult to meet the high damping performance requirements of important public service buildings that have high seismic fortification goals and can still work normally after earthquakes. Traditional methods for improving the damping performance of concrete often greatly weaken its good compressive performance. To solve the problem of mutual exclusion between damping and compressive performance, as well as high carbon emissions for concrete. Firstly, this study proposes a method of using rubbers (R) instead of fine aggregates, and steel slags (S) and fly ashes (FA) instead of some cementitious materials. An environment-friendly high-damping concrete (EHDC) is formulated, which combines high damping performance with good compressive and tensile performance while significantly reducing cement consumption. Secondly, through molecular dynamics simulations, the influence of R, S and FA on Ca-O, Si-O and H-O bonds in EHDC is analyzed from a microscopic perspective, and the transmission mechanism of multi-scale mechanical property information for EHDC is revealed. The influence of R on ion diffusion in EHDC is revealed through MSD analysis of Ca and Si ions. Then, the relationship models between the diffusion coefficients of Ca ions and Si ions and the elastic modulus are established separately. The damping performance and the stress-strain relationship of EHDC under axial tension are analyzed. Finally, the optimal formulation ratio of EHDC that combines good compressive and damping properties is selected. The results indicate that the formulated EHDC can effectively solve the difficult problem of the mutual exclusion between damping performance and good compressive performance, as well as high carbon emissions for traditional concrete. The addition of R can reduce the bonding of Ca-O bonds in EHDC, but there is a certain degree of increase in the bonding of Si-O bonds. When the substitution rates of R, S and FA are between 20% and 25%, the linear slope of MSD for Ca and Si ions in EHDC is the largest. When the substitution rates of R, S and FA are all 10%, EHDC exhibits excellent damping performance while retaining good compressive performance of concrete. The achievement of cross-scale mechanical information transmission between microscopic ion diffusion and macroscopic elastic modulus provides a theoretical basis for the multi-scale design and development of EHDC.