Anwendungszentrum für Holzfaserforschung HOFZET®

Forschungsprojekt

SenAD – Continuous and comprehensive monitoring of the road condition through sensors in the asphalt

The assessment of the structural condition of asphalt base layers is of considerable importance for the planning of road repairs. Currently, destructive measurement methods are used, through which the road under investigation is additionally damaged. Due to the high outlay and the resulting supplementary damage, a continuous evaluation of the base layer is not feasible. In collaboration with two universities, we are developing a non-destructive measurement system with which the road condition can be ascertained at any time and with no significant technical measurement effort. This would enable a more efficient and more timely planning of road repair measures.

Cross-section of an asphalt test specimen with built-in sensor fabric which is visible at the cut edges.
© Fraunhofer WKI | Moritz Micke-Camuz
Bio-based sensor carrier fabric in asphalt test specimen.
Open-weave sacking-type fabric with light-colored threads.
© Fraunhofer WKI | Christina Haxter
A gauze fabric made from natural fibers serves as the carrier material for the sensor technology.

The basis for the measurement system is formed by an electrically conductive material, which is integrated into a fabric. This hybrid fabric is incorporated into the asphalt base layer. The resistance of the sensor material changes due to its structural damage and consequently serves as a characteristic value for its time of failure. The damage processes caused by the loads in the asphalt affect the asphalt and, simultaneously, the integrated sensor fabric. It is therefore possible to infer the time of failure of the asphalt section from the fatigue state of the conductive material. Data on the actual internal condition of the base layer are provided, which, in the long term, can replace the previous drilling tests.

The transmission and storage of the data is also being examined as well as the secure data transport - from the road via various interfaces all the way through to the software and the companies carrying out the work. The processing and evaluation of the measurement results is performed through adaptation of a suitable software. For the interpretation of future measurements, the relationship between resistance change and degradation of the road is illustrated.

The carrier fabric, into which the sensor technology is integrated, is completely bio-based. The fabric development and production is being carried out at the Fraunhofer WKI in close cooperation with the Fraunhofer IFAM. At the Magdeburg-Stendal University of Applied Sciences, the measurement system is incorporated into asphalt test specimens and subjected to mechanical stress. In parallel, researchers at the Fraunhofer IFAM analyze the sensor technology and collect the data. The transport as well as the further processing of the data by means of suitable software are investigated and implemented primarily at the Hochschule Hannover, University of Applied Sciences and Arts.

In order to demonstrate and ensure the practical feasibility, a road-construction company is directly involved in the investigations and is supporting the research institutions in their efforts to define the locally applicable framework conditions.

Results

Together with our project partners, we succeeded in developing the measurement system and demonstrating its applicability. The findings can not only simplify planning in road construction but can also form the basis for many other applications. An integrated measurement system can be implemented in diverse further areas of structural and civil engineering. Furthermore, new functions can be integrated into components used in the construction industry. The project team is already in close contact with representatives from industry, who are showing great interest in the innovative research approaches. Further collaborative research has already been initiated.

Project partners

  • Hochschule Hannover, University of Applied Sciences and Arts
  • Magdeburg-Stendal University of Applied Sciences

Funding

The project is being funded by the German Federal Ministry of Transport and Digital Infrastructure within the framework of the funding guideline “mFUND” (Modernitätsfonds = modernity fund) with a total of around 90,000 euros.

Official project title: Sensorintegration in Asphalt für ein Daten-basiertes Degradationsmonitoring (Sensor integration in asphalt for data-based degradation monitoring)

Funding reference: 19F1070A

Project management: TÜV Rheinland Consulting GmbH

Duration: 01.10.2020 to 30.06.2021

Information on the mFUND of the BMVI

Within the framework of the mFUND research initiative, the BMVI has been funding research and development projects addressing data-based digital applications for Mobility 4.0 since 2016. In addition to financial assistance, mFUND also supports networking between participants from politics, business and research with a variety of event formats and facilitates access to the mCLOUD data portal. Further information can be found at www.mfund.de