The main purpose of the project is the construction of concrete road top layers with due regard to six essential optimisation parameters.
For dense concrete road surfaces the longitudinal textures and the exposed aggregate technology can be optimized in order to minimize the rolling noise without damaging the driving safety. The skid resistance and the aquaplaning behaviour maintain appropriate values for safe driving.
A dense concrete with a durable surface texture and sufficient freeze thaw and polishing resistance, which fullfils the requirements concerning compressive and flexural strength can be produced. Technologies which have been specifically developed for such purposes have proven to be economical and at the same time render high standards of quality.
Porous concrete shows similar noise, skid resistance and texture characteristics to porous asphalt, always based upon the used granulometry, and constructed in 2 ways: wet on wet, and wet on dry.In the wet on dry solution, the bond between the dense concrete bottom layer and the porous concrete top layer is critical. A cement glue is needed. Cement glue composition and its laying system have to be improved.
No clear correlation has been found between the rolling noise and the sandpatch texture index, and consequently, a more representative macrotexture index must be defined. New methods based on the use of laser techniques are at the development stage. No clear correlation has been found between the texture spectra and the noise measurements.
The parameters are:
-Traffic safety: the skid resistance must meet for at least 20 years the requirements in the national road standards
-noise reduction: for dense concrete surfaces the noise production must be reduced to the average value of low noise dense asphaltic concrete
-useful life and economic feasibility: the lifetime of concrete road top layers must be at least 20 years, as is normal for concrete roads. Construction and maintenance costs must be competitive with other types of asphalt and concrete roads, taking into account that for these roads acoustic walls might be needed in order to reduce the noise emission to the surroundings to the level given in national specifications (reduction 3dB as an average compared with present used dense concrete for porous concrete and 5-6dB for dense concrete)
-in the case of a porous concrete top layer the porosity must guarantee over the whole lifetime that even under heavy rainy conditions on the base of maximum rain measured by national meteorological institutes, there is no more water than a thin film (20-25m as a maximum) on the surface
-construction methods must be developed and approved in test sections in order to meet the goals mentioned above. These construction methods must be available for new roads as well as for overlays on existing roads
-description of all knowledge obtained in a code of practice and a guideline to be used in all EC countries.
1117 ZR Schiphol
28820 Coslada Madrid
6130 PD Sittard