The PERSUADE project aims at developing the experimental concept of poroelastic road surfacing (PERS) into a feasible noise-abatement measure as an alternative to, for example, noise barriers.
The project comprises an extensive investigation and testing in the laboratory to develop a durable mixture, the construction of seven test sections in five partner countries, a monitoring effort for the test sections (noise, rolling resistance, skid resistance, durability, winter behaviour, etc.), and a study of all conceivable environmental and economic aspects. The laboratory development is led by VTI in Sweden. The project has been scheduled for a duration of six years.
The Arnakke test site – Denmark
A small size field test of the PERS material, called test “zero”, was carried out in October 2011 preceding the construction of full scale test sections. A 10 m2 test section was constructed by the project partner NCC Roads. It is situated at the Arnakke rest area located alongside the Holbæk motorway in Denmark, about 60 km west of Copenhagen. The test site consists of a ramp from a parking area for passenger cars only. The ramp leads the traffic to the motorway. The traffic volume and the driving speed (typically 30 km/h) are low.
The purpose of this “zero test” was to:
- Gain experience with mixing and laying the PERS material outside the laboratory on a real road
- Monitor the performance of the surface during a winter period and see its behavior with frost, snow and ice
- Obtain a first indication of the durability of the developed PERS mix
- Assess skidding resistance, permeability, acoustical absorption, texture, mechanical impedance, surface temperature and drainability.
A small mixer for cement concrete and a short mixing time of 3 minutes were used when the PERS surface was constructed.
Drainability, absorption, texture and mechanical impedance measurements on the zero test track all indicate that the developed PERS mix has a good potential for noise reduction. However, sometime after the construction mushroom shaped bumps appeared on the PERS surface and at the edge of the test track a pothole started to develop.
Close examination by the PERSUADE team revealed that the bumps were caused by pockets of uncured polyurethane, due to an insufficient mixing and a subsequent reaction with rainwater. The pothole can be attributed to the heterogeneous mixture as well.
An important lesson drawn from this test track in Arnakke is that the mixing is crucial and has to be carried out thoroughly. A very positive result was that PERS does not compromise safety: both the skidding resistance measurements with the VTI developed “portable friction tester” and with the classical skidding resistance tester (SRT) pendulum yielded higher values than the ones measured on the existing asphalt pavement on the Arnakke site.
PERSUADE is the acronym for PoroElastic Road SUrface: an innovation to Avoid Damage to the Environment. The work presented in this article is financed by the European commission as well as by the concerned Danish, Swedish and French PERSUADE partners.
Twelve partners from seven European countries are cooperating in this project, including research institutes, universities and companies representing the involved industry sectors. The three partners from the Nordic countries are the Danish Road Directorate, VTI in Sweden and NCC Roads in Denmark. See also the PERSUADE website at Fehrl.
More information can be found in the report on the PERSUADE homepage: Bendtsen, Olesen, Pigasse, Andersen, Raaberg, Kalman and Cesbron “Measurements at the Arnakke test site with small PERS sections”. Persuade Report 2012.