Innovative low noise surfaces - comparison of damping and absorption

Abstract

While sound absorption is an acoustic related property reasonably well known and currently used tocharacterize low noise surfaces, damping is a property commonly used in other domains to define the energydissipation of a material but rarely used to characterize this important mechanism in road pavements. Thispaper compares noise related properties such as damping and absorption of five road pavement surfaces. Twoof which are innovative and therefore expected to be low noise since they have high voids content,incorporate fine grading aggregates and expanded clay. Other two incorporate rubber and waste high-densitypolyethylene giving them an elastic and stiff behaviour respectively. The fifth is a conventional material,asphalt concrete, used for control. Sound absorption tests and mechanical impedance tests were carried out in30x30 cm slabs at 20ºC. To measure absorption, an impedance tube with an open end was put on the surfaces.To determine damping, the response of a hammer impact measured by an accelerometer on suspended slabswas analysed. Results show that the innovative surfaces have better acoustic related properties while thesurface with high-density polyethylene provided the worst results. Furthermore, a strong correlation ofdamping and air voids was found.