Porous top layer optimization of cement concrete slabs for tyre/road noise reduction

Abstract

The I-STREET CUD-SF project aims at developing an urban pavement made of cement concrete slabs that can be easily removed and replaced for maintenance purposes. These slabs are made of a dense cement concrete body and a functionalized porous top layer ensuring water drainage and sound absorption. In order to optimize the porous layer for tyre/road noise reduction, several mix recipes with different porosity and maximum aggregate size were considered. Recipes with the most interesting absorption properties were preliminary selected based on absorption coefficient measurements performed on cylindrical test specimens with an impedance tube. A second phase was dedicated to evaluation of texture induced coast-by rolling noise levels with the tyre/road noise prediction model HyRoNE from 3D texture scans performed on rectangular laboratory samples. Finally, based on a porous medium model and a propagation model considering the tyre/road noise source as an omnidirectional point source over an impedance plane surface, the porous layer thickness of the selected mix was adjusted to minimize the predicted noise at roadside for different reference rolling speeds. This paper gives an overview of the results obtained at the different stages of the optimization process, prior in-situ assessment of the industrial solution in a near future.