材料设计参数对双层多孔路面吸声性能影响

Influence of material design parameters on noise reduction performance of two-layer porous pavement

为提升双层多孔路面吸声性能,增强对轮胎与路面接触源头噪声的消减效果,给路面降噪功能优化设计提供依据,分析层间结合材料用量、底面层空隙率对双层多孔路面吸声性能的影响规律。采用表面声学阻抗试验获取混合料吸声系数曲线,对比不同层间结合材料用量、底面层空隙率对双层多孔路面吸声系数峰值和峰值频率的影响,并采用层间剪切、拉拔强度试验分析层间黏结性能。基于层间材料用量和底面层空隙率优化,提出一种采用聚氨酯表面层与改性沥青混合料底面层复合的双层多孔路面结构,通过室内试验分析复合路面材料的基本力学特性和吸声性能。研究结果表明:增加层间改性乳化沥青材料用量能够提升层间黏结强度,但会损失双层多孔路面的吸声效果,主要吸声频谱也会受到影响;提高底面层空隙率能够提升双层多孔路面的吸声性能,特别是对于高频噪声的吸收;而当底面层空隙率小于20%时,吸声系数峰值衰减较快。在聚氨酯材料提供足够黏结强度和表面层力学性能的条件下,复合型路面未采用层间结合材料,并提高了底面层空隙率,因此呈现出显著的高、低频吸声效果。为保持双层多孔沥青路面吸声性能和黏结强度的均衡,底面层空隙率不宜低于20%,在保障足够有效吸声功能基础上,宜使用较高的层间结合材料用量。采用复合式双层多孔路面可以同步提高表面层和底面层的空隙率,从而增强吸声性能,具有更为突出的材料力学特性。

For improving the sound absorption property of the two-layer porous pavement,which will lead to an increased performance of reducing noise generated from tyre and road surface interaction,and providing support for optimizing the design of noise reduction function.Influences of material design parameters of a two-layer porous asphalt,including the amount of bonding materials between layers and the air voids content of the bottom layer,on sound absorption coefficients were studied.The sound absorption coefficient curve of the asphalt mixture was obtained by the surface acoustic impedance measurement.The effects of the amount of bonding materials,and the air voids content of the bottom layer on the peak sound absorption coefficients and peak frequency locations were compared.The bonding strengths were observed by measuring the tensile strength and shear strength of the two-layer samples.For further improving the performance of two-layer porous pavement,a composite structure was developed based on control of the amount of interlayer bonding materials and air voids contents of the bottom layer.In this structure,the surface layer was made of mixture using polyurethane as binder,and material of the bottom layer was the modified asphalt mixture.The basic mechanical performances and sound absorption properties of the composite pavement materials were observed and analyzed by laboratory tests.The results show that increasing the amount of modified emulsified asphalt between the porous asphalt layers can improve the bonding strength,but it will reduce the sound absorption performance of the two-layer sample,as well as influencing the frequency interval of sound absorption coefficient distribution.Improving the air voids content of the bottom layer can increase the sound absorption performance of the two-layer porous pavement,especially for noise absorption at high frequencies.When air voids content of the bottom layer is less than 20%,the peak value of the sound absorption coefficient will decrease obviously.Under the condition that the polyurethane provides sufficient bonding strength and mechanical performance of the top layer,the bonding material is eliminated in this structure and air voids contents of both layers are improved.A significant sound absorption effect is demonstrated at both high and low frequencies for the composite pavement structure.In order to obtain a balanced sound absorption and bonding strength of two-layer porous asphalt,the air voids content for bottom layer should be no less than 20%.On the basis of ensuring sufficient sound absorption,a larger amount of bonding material is suggested to be used.For the composite two-layer porous pavement,the air voids content for both layers can be increased to some extent,in order to improve the sound absorption performance and obtain prominent material mechanical properties.2tabs,8figs,23refs.