Libs: An innovative laboratory technique for the characterisation of bituminous material

Abstract

The principal use for bitumens is in road construction. Some of the properties of bitumens, for example their consistency, change throughout their life, from manufacture to the end of their service life. Analytical techniques can be used to ascertain their chemical structure but not fully, due to the complexity of their composition. For several years, variability in the quality of bitumen has been observed. The conventional laboratory tests performed on bituminous materials are unable to identify any difference between the binders in question. More detailed studies reveal that they differ in terms of their elemental composition, for example the metals they contain, which are also markers of the origin of the crude oil. Metal contents can be quantified by various analytical techniques such as Atomic Absorption Spectroscopy (AAS) and Inductively Coupled Plasma (ICP) which are unfortunately quite complex to perform. Recently, a laboratory technique for determining the elements present in materials has attracted the attention of the scientific community. This method, known as Laser Induced Breakdown Spectroscopy (LIBS), uses a laser coupled with an optical emission spectrometer. We have adapted the LIBS protocol to make it suitable for the characterization of bituminous materials, and it represents a highly innovative technique for bitumen testing. This method is compatible with the precepts of sustainable development because, amongst other things, it does not use any solvents and generates no waste. This paper explains the principle of the LIBS technique, the necessary equipment, the way it is set up and practical applications in the field of road construction.