Enhancing of damping capacity in crumb rubber concrete at various damage levels: Effects of fly ash and ground granulated blast furnace slag

Abstract

Crumb rubber (CR) incorporated as damping units in concrete, partially replacing natural aggregates, enhances the material's damping capacity. However, the filler type and replacement rate will usually influence the crack development of crumb rubber concrete (CRC) elements under repeated loading, which in turn influences their damping capacity at different damage levels. Thus, the damping characteristics of CRC cantilever beams at different damage levels, influenced by filler type and substitution rate, are investigated in the present paper through low-cycle repeated damage and free vibration tests. The results reveal that partial cement replacement with fly ash (FA) significantly enhances the energy dissipation capacity, especially at a 30% FA replacement rate. Positive effects on the damping ratio are observed only when the ground granulated blast furnace slag (GGBFS) substitution rate is 30%. For the CRC cantilever beams both with and without filler, the damping ratio shows an increasing and then decreasing trend with increasing displacement angle. The maximum damping ratio is exhibited when the displacement angle is 0.02. With increasing displacement angle, FA and GGBFS doping accelerated the degradation rate of the bending dynamic stiffness and the damage index rose faster. A model is formulated to describe the correlation between the damping ratio and the damage index in CRC cantilever beams both with and without filler. The effect of filler incorporation on the pores and microcracks may be the main reason for the damping ratio increase as observed by micro-microscopy.