About the project:

Ravelling is a common mode of early failure for many types of asphalt pavement. There are several potential causes for this loss of aggregate particles, so it is difficult to assess the theoretical potential to ravel of an asphalt mixture in the design stage. Recently, several simulative laboratory tests have been developed that are claimed to give an indication of that potential. These tests use scuffing machines that repeatedly apply a scuffing action to slab ~ samples to replicate in service loading. The test methods for four such scuffing machines have been written up as a draft technical specification by Comité Européen de Normalisation (CEN) as prCEN/TS 12697-50, Resistance to scuffing. However, these methods need rationalised so that one single measure exists that has good precision and is validated
against site performance.

This project will seek to validate existing testing methods to simulate asphalt ravelling in laboratory conditions. The appropriate CEN committees responsible for draft technical specification prCEN/TS 12697-50, Resistance to Scuffing will be engaged in the course of the project. The project has eight partners coordinated by TRL. Ravelling tests will be coordinated across six laboratories at: BRRC (Belgium), IFSTTAR (France), BAM and Heijmans (the Netherlands), and TU Darmstadt and ISAC-RWTH (Germany). Independent assessment of the results will be undertaken by TNO (the Netherlands) and TRL.

DRaT has been commissioned by CEDR in response to the 2014 call on Asset Management and aims to build on the results of the previous 2010 ENR call on “Effective Asset Management meeting Future Challenges”.

Time frame

The project commenced in September 2015 and will conclude in August 2017.

Project delivery team

This project is sponsored by CEDR

The consortium has eight partners and five work packages:

TRL, United Kingdom

Coordinating and leading WP1 (review) & WP5 (dissemination)

BAM infra, the Netherlands

Leading WP2 (sample preparation) and testing using the ARTe device

BRRC, Belgium

Leading WP3 (test programme) and testing using the DSD device

TNO, the Netherlands

Leading WP4 (analysis)

ISAC, Germany

Testing using the ARTe device

TUDA, Germany

Testing using the DSD device

Heijmans, the Netherlands

Testing using the RSAT device


Testing using the Triboroute device

Further Information

The project’s nine deliverables can be found at the links below

Key outputs

D1: Flyer for project

Summary of the project scope, objectives and deliverables.

October 2015

D2: Review of parameters influencing propensity to ravel

Identifies factors that contribute most to the phenomenon of ravelling in surface course asphalts.

December 2015

D3: Compendium of sites and the extent of ravelling

Summary of the project scope, objectives and deliverables.

October 2016

D4: Result reporting template

Used to collect the laboratory results in a standardised format.

February 2016

D5: Report detailing properties of manufactured slabs

Collates the properties of each manufactured slab for future reference.

November 2016

D6: Interim report

Describes progress made in the first eight months of the project.

July 2016

D7: Factual report on test results

Summarises the raw data from laboratory testing collected via the result reporting template.

May 2017

D8: Report on analysis of results

Provides a full interpretation of the results, analysing the performance of the laboratory test methods.

July 2017

D9: Final report giving recommendations for the standard

Suggests how the standard might be revised based on the overall findings of the project.

July 2017