Development of a new methodology for characterization of polymer modified bitumens ageing by infrared microspectrometry imaging

Title: Development of a new methodology for characterization of polymer modified bitumens ageing by infrared microspectrometry imaging
Author(s): V. Mouillet, J. Lamontagne, J. Kister, D. Martin
Paper category : conference
Book title: Sixth International RILEM Symposium on Performance Testing and Evaluation of Bituminous Materials
Editor(s): M. N. Partl
Print-ISBN: 2-912143-35-7
e-ISBN: 2912143772
Publisher: RILEM Publications SARL
Publication year: 2003
Pages: 153 - 159
Total Pages: 7
Nb references: 20
Language: English

Abstract: Increase in traffic volume has led to wider use of Polymer modified Bitumens (PmBs) in road construction. Although the mechanical properties of such materials have been widely studied, their change with time in service, also called ageing, is yet to be fully understood.
One of the most important issues is to identify the process involved : is PmB's ageing a consequence of bitumen ageing, polymer ageing or both at the same time? Additionally, most PmBs feature a two-phase structure made of polymer rich areas along with polymer poor regions, depending on the bitumen chemistry, the polymer nature and content. It is therefore important to take this into consideration when trying to sort out the respective effect on ageing of the polymer and the bitumen. FTIR microscopy is a suitable technique to analyse chemically and punctually in situ micro-phases of a material. By means of a motorized x-y sample stage and an appropri-ate software, the micro-morphology of a PmB can be studied by mapping functional group on a large area of a sample.
This paper presents the results of a study of the ageing of different PmBs containing either saturated plastomers or unsaturated elastomers. Firstly, PmB's ageing throughout its whole service life could be simulated by applying conventional ageing tests, RTFOT, for the mixing process and laying of asphalt concrete, and PAV for in service ageing. Changes in the bitumen properties before and after ageing were thus recorded. Secondly, an ageing cell specially designed to fit the FTIR microscope was developed to study directly and continually the PmB's oxidation by FTIR microscopy imaging. The results obtained by following simultaneously both phases evolution, allow to propose a method to measure changes in PmB's chemical composition. These changes are both bitumen and polymer dependent. Finally, the kinetics study shows that RTFOT and PAV can be simulated in the ageing cell in a quicker way.
In conclusion, the design of an ageing cell associated to the FTIR microscope appears to be a very effective tool to observe and chemically study the microstructure of PmBs during ageing. It also gives some insights to evaluate PmB's durability.

Online publication: 2003-03-02
Publication type : full_text
Public price (Euros): 0.00
doi: 10.1617/2912143772.017