大孔隙胶粉改性沥青混合料吸声特性试验研究

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

利用驻波管对孔隙率为20%的大孔隙胶粉改性沥青混合料和孔隙率为4%的SBS改性沥青混合料试件进行试验。分别对3cm、4cm、5cm厚度的两种试件按1/3倍频测定吸声系数。试验结果表明:随试件厚度的增加吸声系数增大;大孔隙胶粉改性沥青比SBS改性沥青混合料试件吸声效果明显提高。同时,利用阻尼衰减振动特性测试仪器对两种改性沥青混合料车辙板试件进行轮胎垂直自由落体衰减振动试验。可以看出,与SBS改性沥青混合料相比,胶粉改性沥青混合料试件系统的垂直衰减振动阻尼比D值和损耗因子1/Q值增大约5倍,且自由衰减振动的振幅衰减程度大,即胶粉改性沥青混合料试件具有更好的阻尼特性和降噪功能。因而进一步证明,用大孔隙胶粉改性沥青混合料铺筑路面具有较好的降噪效果。

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 carded 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.