Rubber wear on concrete: dry and in-water conditions

Rubber wear results from the removal of small (micrometer-sized) rubber particles through crack propagation. In this study, we investigate the wear behavior of Styrene-Butadiene Rubber (SBR) and Natural Rubber (NR) sliding on two different concrete surfaces under dry and wet (in water) conditions. Experiments are conducted at low sliding speeds ($\approx 3 \ {\rm mm/s}$) to minimize frictional heating and hydrodynamic effects. For two SBR compounds, we observe significantly higher wear rates in water compared to the dry state, with enhancement factors of $1.5-2.5$ for a low-glass-transition-temperature SBR compound ($T_{\rm g} = -50^\circ {\rm C}$) and approximately $4$ for a higher-glass-transition compound ($T_{\rm g} = -7^\circ {\rm C}$). In contrast, the NR compound showed no wear in water at low nominal contact pressures ($\sigma_0 \approx 0.12$, $0.16$, and $0.25 \ {\rm MPa}$), while at higher pressures ($\sigma_0 \approx 0.36$ and $0.49 \ {\rm MPa}$), the wear rates in dry and in-water states are similar. The findings provide insights into the mechanisms of rubber wear under varying environmental and mechanical conditions, highlighting the influence of material properties, interfacial effects, and applied pressures on wear behavior.