The Belgian standard specifications for road construction contain several clauses on surface treatment techniques.  Their goal is to improve certain surface characteristics without jeopardizing other ones, e.g. improving noise behaviour while maintaining or improving skid resistance and evenness. The most used techniques are diamond grinding and fine- and micromilling. Other treatments, mainly used for decorative pavements, are hammering (“bouchardage”), sand- or shotblasting, hydrojet and honed concrete. 

The first experiences on both diamond grinding and milling date from the 1990’s when some test sections were treated on motorways E314 and E40.  The results were excellent, especially for the diamond ground surfaces. This technique was used later on for a number of noisy surfaces of regional and local roads, mainly through town centres, in order to abate the rolling noise.  Fine milling is often applied mainly on municipal roads; it is less performing but cheaper compared to diamond grinding. A new promising development is micromilling with a finer texture compared to fine milling. 

Recently, technical prescriptions were added for the combination of grinding and grooving, the so called “Next Generation Concrete Surface” (NGCS), a newly developed technique coming from the United States, to reduce rolling noise. Thanks to diamond blades, a negative texture is ground each time with 1 deeper groove and 4 shallow grooves in the longitudinal direction. It can be applied on new concrete surfaces as well as on existing pavements. The first Belgian trial section, composed of 2 different profiles, was carried out on an existing jointed concrete road with exposed aggregate surface, in October 2015 on the regional road N44 in Maldegem. The difference between the profiles was in the spacers, which were considerably narrower for the first profile. Noise measurements, both CPX and SPB, were done right after the treatment and after a half year and a year.  The first profile performed the best:  CPX results, immediately after treatment, showed that the noise level of cars decreased by 6 dB (A) compared to the existing surface. Compared with the reference pavement SMA-C (stone mastic asphalt with maximum aggregate size of 10 mm) the level obtained was 3 to 4 dB(A) quieter. A year later, the difference was still 4 dB (A). For heavy vehicles, the CPX measurements were less conclusive but the SPB measurement showed again a significant reduction. The results are very promising but further monitoring and new sections are necessary. 

The driving surface is of utmost importance for the safety and driving comfort of the road user.  When surface characteristics don’t meet the requirements (anymore), several mechanical treatments are available, which allow to extend the lifetime of the concrete pavement, without the need of an overlay.

Die Kurzfassung zur Veranstaltung ist im PDF verfügbar.