EXPERIMENTAL STUDY ON SOUND ABSORPTION OF CRUMB RUBBER MODIFIED ASPHALT MIXTURE WITH LARGE POROSITY

The Standing wave tube experiment is carried out for the specimens of Crumb Rubber modified asphalt mixture with 20% porosity and the SBS modified asphalt mixture with 4% porosity. The absorption sound coefficient is measured at 1/3 multiples frequency to the 3 cm，4cm，5cm specimens. The result of the experiment shows that the absorption coefficient increases with the thickness of specimen increasing，and the sound absorption effect of the specimen with its large porosity which was made of Crumb Rubber modified asphalt mixture is much better than that of the specimen made of SBS modified asphalt mixture. In the meantime，the free falling bounce test for two kinds of modified asphalt mixture plate specimens is carried out by a damped vibration testing instrument. It is observed that in comparison with SBS modified asphalt mixture，Crumb Rubber modified asphalt mixture specimen system damped vibration subsidence ratio D and loss factor 1/Q becomes five times as great，and the amplitude decays more faster. Therefore，Crumb Rubber Modified Asphalt Mixture has better damping characteristic and sound insulation fall function. Consequently, the pavement with Crumb Rubber modified asphalt mixture of large porosity results in better characteristics of sound absorption.