Mix Type Selection
Pavement type selection processes are used by pavement authorities such as state highway agencies to identify the most beneficial type of pavement structure for a given set of traffic, soils, climate, and other factors. They may be as simplistic as specifying a certain type of pavement on the basis of traffic level, or they may be as complicated as assigning weighting factors to more than a dozen characteristics and evaluating the outcome through a scoring system. Whatever process is used, it should be a rational and explainable methodology in which the effects of different variables on decision making may be determined. Information used to develop the process should reflect documented historical performance and cost records.
The 1993 AASHTO Guide for the Design of Pavement Structures, published by the American Association of State Highway and Transportation Officials, outlines the considerations for pavement type selection in its Appendix B. The principal factors to be considered include traffic, soils characteristics, weather, construction considerations, recycling, and cost comparison. The secondary factors include performance of similar pavements in the area, adjacent existing pavements, conservation of materials and energy, and availability of local materials, among other issues.
The Asphalt Pavement Alliance has developed a position paper in order to discuss the primary considerations in pavement type selection as presented in the AASHTO Guide in detail, and to present the advantages available from Hot Mix Asphalt pavements in each of these. Additional considerations include the issue of tire-pavement noise generation, ride quality, and safety, and the advantages asphalt offers in these characteristics.
To download the PDF on Pavement Type Selection, click here.