Asphalt does not last forever. At some point, it ages and starts to crumble. This has to do with the bitumen, the sticky binding agent, which holds and keeps the rock content in the asphalt. Bitumen is a petroleum product consisting of several organic components, which undergo a chemical change over time. Until now, the condition of bitumen could only be approximately measured in a laboratory. At the Vienna University of Technology, a much easier and more accurate method has now been developed: By means of a fluorescence analysis, this small, mobile hand scanner can measure the bitumen’s quality in a quick and simple way.
Aged bitumen loses its useful properties
"Several causes can have a negative impact on the bitumen’s quality”, explains chemist Prof. Hinrich Grothe from the TU Wien. Together with the team of Prof. Bernhard Hofko, traffic scientist at the TU Wien, he conducted an in-depth study of bitumen. “Environmental influences or manufacturing faults can lead to the aging of bitumen - it loses its elasticity and becomes brittle and fragile”, explains Grothe. “The aging of bitumen is a serious problem for road construction, but also for the waterproofing of buildings.”
Until now, bitumen has mostly been explored by means of mechanic measuring methods. There are more than 100 different, standardized procedures for the quality measurement of bitumen, but these procedures can only be carried out by trained staff in a laboratory. “There must be an easier way to do this”, thought the staff at the TU Wien - and developed a measuring tool based on a fundamentally new principle.
The hand scanner functions with LEDs, which stimulate the bitumen’s fluorescence. “Due to the aging of bitumen, its composition changes, particularly the proportions of important components such as alkanes, aromatics, resins, and asphaltenes”, explains Hinrich Grothe. “The fluorescence measurements reflect the shifts of these proportions.”
As it shows, new bitumen can be clearly differentiated from aged bitumen in terms of its fluorescence. “We have identified three wavelengths that are particularly suitable for quality control”, says Grothe. “Thus, it is no longer necessary to measure a full spectrum - instead, it is fully sufficient to conduct three individual measurements with blue, violet and ultraviolet light.”
Handy fluorescence scanner
Based on these insights, a portable, handy scanner was developed, by means of which a reliable measurement can be performed within seconds. Thus, complete quality control of bitumen becomes possible. In order to use this method in the future not only for analysing new bitumen, but also for recycled bitumen consisting of existing asphalt pavements, data is being collected at the moment. In the future, the bitumen’s reusability will thus be assessable at the push of a button. It is already possible to measure whether a certain bitumen has changed its quality between refinery and paving. The bitumen scanner can be used in the fields of production, storage, and processing, as well as for the multifaceted application of bitumen in road construction, the sealing of buildings, or, for corrosion protection of technical components.
Apart from the bitumen scanner, the TU Wien will introduce the following innovations at the “Advantage Austria”-Booth (Hall 6 - Booth D18, from 24. to 28.4.2017):
- The sensorless control of synchronous motors by means of the INFORM®-method, including:
-- The synchronous reluctance machine, which, in terms of efficiency and cost, offers a highly interesting alternative to classic asynchronous motors: Given its simple construction, it requires less assembly space and generates a third less losses.
-- The sensorless permanent-magnet synchronous drive, which convinces with its high compactness and its excellent efficiency.
- The highly dynamic, sensorless magnetic bearing, which enables levitated rotating machine shafts at low cost.
- The top innovation, which is being presented at the Hannover Messe for the first time: the worldwide first electric planet motor with integrated gear and particularly high power output.
Picture download: www.tuwien.ac.at/hm2017
Regarding scientific questions:
Prof. Hinrich Grothe
Institute of Materials Chemistry
Getreidemarkt 9, 1060 Vienna
Regarding the TU’s presentation at the Hannover Messe:
Dipl.-Ing. Peter Heimerl
Department for Research Marketing
Karlsplatz 13, 1040 Vienna