7 INTERNATIONAL CONFERENCE ON ASPHALT PAVEMENTS th TOWARDS ANALYTICAL MIX DESIGN FOR LARGE- STONE ASPHALT MIXES F C Rust, Pr Eng. J E Grobler, Division of Roads and Transport Technology, CSIR, Pretoria, South Africa P A Myburgh, Pr Eng, Southern African Bitumen and Tar Association. F Hugo, Pr Eng, Professor, University of Stellenbosch, South Africa Increasing traffic volumes and axle loads in South Africa has recently resulted in traffic loading beyond the current design classes. In addition, there is a strong lobby to increase the legal axle load limit. A need was expressed by the Southern African Bitumen and Tar Industry for an investigation into Heavy Duty Asphalt Pavements. A project focussing on the use of large-aggregate asphalt mixes (37,5 mm and 53 mm) was defined. This paper addresses the development of an analytically based design procedure for large-aggregate asphalt and its application in thirteen trial sections. In addition, the physical and engineering properties of the various materials are discussed and related to the constructability of the mixes. The performance of these trial sections under accelerated trafficking are related to laboratory results. INTRODUCTION Increasing traffic growth in terms of both volume and axle loads is a world-wide phenomenon. In South Africa this has resulted in traffic loading on some of the major highways in excess of the current design classes. There is also currently a strong lobby to increase the legal axle load limit from 8,2 tonnes to approximately 10 tonnes. In addition, higher tyre pressures due to new tyre types exacerbate the situation. Both the South African road authorities and the South African asphalt industry expressed a need for an investigation into Heavy Duty Asphalt Pavements (HDAPs). The main aims of this project were to assess the ability of HDAPs to carry very heavy traffic, to develop design procedures for such materials, to assess their constructability and to evaluate their benefit in terms of economic analysis. The project focussed on the use of large-aggregate asphalt mixes as a possible solution to the above problem. The use of 37,5 mm and 53 mm aggregate in various gradings was investigated. This paper addresses the development of a design procedure for large-aggregate asphalt, the implementation thereof in trial sections, the correlation of laboratory obtained engineering properties with field values, the effect of constructability on engineering properties and the performance of these trials under Heavy Vehicle Simulator (HVS) testing. As part of this work thirteen trial sections were constructed with various aggregate gradings, binder contents and types of binder. These are located near Cape Town and