Reconciling the structural design of bitumen stabilised materials - heuristic versus mechanistic empirical models

The use of BSM technology is growing worldwide as a practical, economic and sustainable solution for the rehabilitation of the ageing road network. This paper describes the update of the South African Technical Guideline (TG2) for BSMs, the third edition of which was released in 2020. The paper particularly focusses on the structural design methods, but also discusses the revised mix design procedure, updated DEMAC Material Classification System and the pavement investigation and evaluation guidelines given in TG2 (2020), as these processes and analyses provide the inputs for the structural design. This highlights the strong links between material investigation, classification, mix design and structural design. Two methods of structural design for BSMs have been incorporated, and updated Pavement Number (PN) and a Stellenbosch Design Function for BSMs for use in Mechanistic-Empirical Design. The techniques and data used in the development of these methods are presented. The paper also includes a comparison of both methods by comparing eight pavement structures.

Automated summary

The paper describes the updates of the South African Technical Guideline (TG2) for BSMs, focusing on structural design methods and discussing revised mix design procedures, updated material classification systems, and pavement investigation and evaluation guidelines. It highlights the strong links between material investigation, classification, mix design, and structural design, presenting two structural design methods for BSMs. The paper also includes a comparison of eight pavement structures utilizing the two methods.