The development of cost-effective pavement design approaches using minerology tests with new nano-technology modifications of materials

Abstract

The current official road pavement design manuals used in southern Africa dates back to the 1980s. In addition, materials criteria in general use are based on empirically derived tests, the majority of which were developed in the northern hemisphere more than 50 years ago. These material criteria often lead to the exclusion of naturally available materials due to the possibility of “problem” materials that “may” lead to premature pavement failure. New testing technology (e.g. XRD scans) developed to determine the mineral composition of materials allows engineers not only to allow these “problem” materials to be identified, but also to address the “perceived risk” of these materials during the design process. New proven Nano-technologies developed over the last decade also allow engineers to adequately counter the presence of such problematic minerals. The introduction of these technologies in the road construction industry in southern Africa can considerable reduces the unit costs of much needed road infrastructure. The Gauteng Province Department of Roads and Transport (GPDRT) recognised the potential impact of the fast-tracking of these technologies in the road sector. Not only are these technologies already being implemented in the province, but the GPDRT also undertook to fund road demonstration sections for the Accelerated Pavement Testing (ATP) using the Heavy Vehicle Simulator (HVS) of the department as operated by the CSIR. In co-operation with the University of Pretoria, recommendations with regard to the classification, testing and applicable material criteria of Nano-Modified Emulsions (NME) stabilising materials have been developed as a prerequisite to facilitate full scale implementation of these new technologies. The objective of this paper is to describe the initial outcome of the research programme. A basic pavement design catalogue utilising NME stabilisation of naturally available materials for the HVS demonstration sections have been developed for comparison with typical road pavement structures currently in use.