A new hot-mix design method for Southern Africa

The paper describes the background, structure and components of a new hot-mix asphalt design method for Southern Africa. The design method is a result of a two-year project coordinated by a project management group consisting of representatives from research agencies, client bodies and industry. The new design method is centred on spatial design concepts and established knowledge of mix design, with additional validation of expected performance being attained through laboratory tests and prediction models. The mix design method integrates pavement structural design concepts with knowledge of mix type behavior to provide guidelines for mix type and layer thickness selection. Information on traffic volume, climate and the geometric situation is used to rank design objectives and select appropriate performance tests. Stochastic modelling concepts are also introduced, particularly to assess rutting potential as well as the effects of gradation variability on volumetric design parameters. The paper provides an overview of tests and procedures used for the evaluation of rutting, fatigue, durability, moisture sensitivity and permeability. Aspects related to the implementation program are also discussed in the paper. (a) For the covering entry of this conference, please see ITRD abstract no. E202467.