Alternatives for the Optimization of Aggregate and Pavement Properties Related to Friction and Wear Resistance.

摘要

Utilizing literature review,expert opinions,research experience and limited tests,the following findings were obtained. Aggregates having a relatively high content of hard minerals accompanied by relatively high levels of differential hardness or porosity and good bonding of grains will resist both polishing and wear. The shape,size and distribution of the aggregate particles and of the grains within the particles also play a significant role in aggregate and surface performance. The levels of friction required by existing traffic and environmental conditions depend upon the presence of adequate surface microtexture at low speeds and the presence of both microtexture and macrotexture at high speeds. Equations to predict skid numbers from texture indicators were developed. Tire noise and tire wear were found to be mainly a function of tire characteristics. However,noise increased as the surface texture became very dense or very coarse and tire wear increased with increasing microtexture or when tire slippage occurred. The effect of aggregate and texture on rolling resistance is small except at extreme macrotexture levels. Open graded surfaces which provide good skid resistance also reduce glare,splash and spray. Known processes and innovations for aggregate beneficiation and for producing synthetic aggregates have been reviewed and discussed. Recommendations are made on properties,processes,testing procedures,and materials that appear promising and warrant further studies. An economic evaluation of various surfacing systems revealed that the costs of tire wear,accidents and noise are significant in that order,and that a 'Systems Cost'is the most important consideraton in choosing the system.