开级配沥青磨耗层降低路面噪声优化

Optimization on open-graded friction course asphalt pavement based on noise reduction capacity

为了评估开级配沥青磨耗层(OGFC)在降低路面噪声方面的性能,采用击实法制备了20种集料级配组成的OGFC混合料(OGFC-16、OGFC-13、OGFC-10和OGFC-5)马歇尔试件,利用驻波管按1/3倍频测得了不同试件的吸声频谱,并与密级配沥青混合料(AC-13)进行了对比.结果表明:OGFC混合料的吸声频谱近似呈现出先升后降的变化规律,AC-13混合料的吸声频谱没有明显起伏变化,OGFC混合料的吸声系数要远大于AC-13;随着空隙率的增加,OGFC混合料的平均和峰值吸声系数逐渐增大,峰值频率向高频方向移动,并得到了吸声系数和降噪值随空隙率变化的数学表达式;对于空隙率相近的OGFC混合料,平均吸声系数几乎不受级配组成的影响,峰值频率随着公称最大粒径的增加向高频方向移动;随着试件厚度的减小,同一OGFC混合料试件的峰值吸声系数略有增加,峰值吸声频率向高频方向移动,但平均吸声系数明显衰减.因此,在满足路用性能和排水性能的前提下,降噪效果可作为优化OGFC混合料的依据,其空隙率宜为20%~23%.

Marshall specimens of open graded friction course(OGFC)asphalt mixture(including OGFC-16,OGFC-13,OGFC-10 and OGFC-5)with 20 kinds of gradation composition were prepared by the compaction method.The sound absorption spectra of all asphalt mixture specimens were measured by one-third octave frequencies using the standing wave tube and compared with that of dense gradation asphalt mixture(AC-13).The results show that the sound absorption coefficient of OGFC mixture increases first and then decreases with frequency.However,the sound absorption coefficients of AC-13 specimen change relatively smoothly with frequency,much smaller than those of OGFC specimens.The average and peak sound absorption coefficients of OGFC specimens increase with the increase of void content,and the corresponding peak frequency exhibits a tendency moving to the high frequency direction.The mathematical expressions of sound sound absorption coefficient noise reduction value varying with void content are obtained by the fitting method.For the OGFC specimens with void content closely,the average sound absorption coefficient is almost independent of the change of gradation composition,and the peak frequency moves to high frequency with the increase of the nominal maximum particle size.As OGFC specimen thickness decreases,the peak sound absorption coefficient increases slightly,and the peak frequency moves to the high frequency direction,but the average sound absorption coefficient decreases obviously.On the premise of meeting the requirements of pavement strength,stability,durability and drainage performance,the noise reduction effect can be used as the basis for optimizing the OGFC mixture,and the void content should be 20%to 23%.