Analytical techniques to quantify modifiers in bitumen for the South African asphalt pavement industry

Abstract

Modifying bitumen is currently a common practice in South Africa. The asphalt pavement industry has seen an increase in use of different types of modifiers in an attempt to improve or extend the properties of bitumen. Common modifiers used in South Africa include plastomers (e.g. ethylene vinyl acetate or EVA), elastomers (e.g. styrene-butadiene-styrene or SBS) and warm mix additives (e.g. waxes). Bitumens are already complex materials which can be represented mechanically and rheologically with mathematical models. Recently, the need to also characterise the in situ structural and chemistry effect of modifiers within bitumen has been appreciated, in order to determine their influence on modified bitumen performance. This paper explores the analysis of bitumen with various modifiers using Fourier Transform Infra-Red (FTIR) spectroscopy and Differential Scanning Calorimetry (DSC). Special attention is paid to quantification of these modifiers in bitumen as a quality control and forensic investigative tool, due to the current asphalt failure challenges facing the industry. The aim is to accurately determine the extent of modification through analytical techniques as a monitoring tool for the better construction of asphalt pavement roads. The paper shows such analytical scientific techniques have the potential to quantify locally used modifiers in South African bitumen.