Laboratory evaluation of road construction materials enhanced with nano-modified emulsions (NMEs)

Abstract

Nano-modified emulsions (NMEs) have recently been used successfully across a number of trial projects in South Africa. Following the development of initial draft design approaches for NME stabilising agents, the Council for Scientific and Industrial Research (CSIR) has decided to evaluate these technologies more extensively by means of an independent laboratory-based research investigation. The aim of this paper is to present the initial results of this investigation, comprising an initial desktop study and a preliminary laboratory evaluation on NME materials in comparison to standard bituminous stabilised materials. The laboratory tests conducted form part of an extensive laboratory evaluation that may be used to verify existing preliminary material specifications for NME materials as well as correlate future test results obtained from Heavy Vehicle Simulator (HVS) tests on several NME demonstration sections. Nano-modified materials consisting of varying mineralogies are investigated using standard laboratory tests, with comparisons being made relative to materials enhanced with standard bitumen emulsion. Based on the results illustrated in this paper, various interpretations and correlations were made between the desktop study and the laboratory evaluation in terms of general trends expected and observed. The laboratory results conclude that NME materials perform significantly superior to standard bituminous stabilised materials, which may have direct implications for improved cost-effective pavement design alternatives. This paper additionally provides initial observations and limitations encountered during the treatment and laboratory testing of these materials, and these are presented together with recommendations being made, regarding the performance and use of NMEs as innovative stabilising agents for road infrastructure.