Effect of dry deposited particles on the tire/road friction

Assuming that friction is governed by the surface fraction (X) covered by particles, a model was developed. The calculated friction coefficient is a weighted sum of friction coefficients when the surface is respectively clean (X=0) and fully covered by particles (X=1). It was found that the surface fraction can be expressed as a function of the ratio of available particles' mass to initial particles' mass. Comparisons between model and experiment are satisfactory. Discussions are made in terms of interactions between surface textures and particles' size and concentration.