Evolution of aggregate surface texture due to tyre-polishing

Three kinds of aggregates were polished by genuine pneumatic rubber tyres.The initial states of surface texture and dynamic friction coefficient were measured and their developments in polishing process were monitored.The characterizations of height distribution and power spectral density of aggregate surface texture were estimated.The changes of micro-texture were also investigated based on a fractal filtering method with sound theoretical backgrounds of rubber friction on rough surfaces.Global height reduction and differential removal of mineral component are observed in polishing process.It is concluded that the tyre-polishing action plays the critical roles in the micro-scale texture,and the evolution of friction of aggregate is governed by the micro-texture changes due to the differential removal of mineral component.

A mechanical system to predict wet grip potential of pavements

A precise friction model is essential for the prediction of tyre wet grip performance and optimization of pavement surface texture design.A mechanical system for predicting the wet grip potential of asphalt pavement was systematically presented using an extended rubber material model by a time step integration scheme.This analytical approach was transferred to a 2D numerical multi-body system consisting of interconnected masses,coupling spring and elementary rubber element of a generalized Maxwell model of rubber tyre tread.The system consists of two basic modules with the same program structure and algorithm,considering the frequency-,temperature-,and strain-dependency behaviors of the complex dynamic modulus of rubber element.The dependence of penetration depth and friction coefficient on the velocity was simulated and validated.It can be concluded that this system can be used for predicting the wet grip potential of asphalt pavements.