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Study on the Influential Factors of Noise Characteristics in Dense-Graded Asphalt Mixtures and Field 时间:2018-09-01 09:51 来源:未知作者:admin 点击: 次 Abstract:Determining the influential factors of noise characteristics in dense-graded asphalt mixtures and field asphalt pavement is important in constructing highways that are both low noise and environmentally friendly. In this study, the effects of nominal maximum aggregate size, asphalt binder type, air void percentage, and the service life of pavement on the noise absorption characteristics of asphalt mixtures were first investigated in laboratory. Thereafter, tire/pavement noise measurements were conducted on different types of dense-graded asphalt pavements. The effects of the service lives of the pavements, the types of the pavements, driving speeds, and test temperatures on the noise levels of the pavements were also studied. The Zwicker method is used to calculate psychoacoustic parameters on the tire/pavement noise spectrum. The laboratory results indicate that reducing the nominal maximum aggregate size, using rubber asphalt, and increasing air void percentage as well as surface texture depth improve the sound absorption performance of asphalt mixtures. The field measurements show that laying down asphalt pavements with a shorter service life or larger texture depth, using rubber asphalt, reducing traffic speed, and increasing air temperature can reduce noise.
1. Introduction
Traffic noise is one of the primary contributors to sound pollution in a city [1, 2]. It has been widely recognized that traffic noise can introduce issues in long-term psychosocial health and well-being [3]. In general, traffic noise can come from four different sources: engine noise, exhaust noise, aerodynamic noise, and tire/pavement interaction noise. Among them, tire/pavement interaction is the dominant noise source for properly maintained vehicles at speeds above 50 km/h [4–7]. Therefore, knowing how to reduce tire/pavement noise plays an important role in controlling the problems associated with highway noise.
Many past studies have focused on optimizing the design and manufacture of quieter automobiles and tires [8, 9], effectively constructing sound barriers [10, 11], planting noise absorbent tree belts on both sides of a highway [12], and paving low-noise or porous pavement [13, 14]. Nevertheless, it must be noted that the reduction in the amplitude from tire/pavement noise caused by the improved design and manufacture of a car or its tire has begun exhibiting diminishing returns. On the other hand, sound barriers and noise absorbing tree belts are limited in their potential application due to the impact they have on the surrounding road space as well their engineering costs. As a result, low-noise pavement has been developed and applied in many sites to reduce tire/pavement noise [15].
Porous asphalt pavement was used mostly as the low-noise pavement of choice over the past twenty years [16]. It had been reported that the reduction on the sound pressure level of noise is 3∼5 dB for porous asphalt pavement [17]. However, porous asphalt pavement suffers from a shorter service life when compared with dense asphalt mixes, and this consideration has discouraged its widespread application [18]. In fact, most of the asphalt pavement used in worldside highways is made of dense asphalt mixes. Therefore, how to control and reduce the tire/pavement noise from dense-graded asphalt pavement has become a central question with important strategic implications for developing quieter environment in the future. Regardless, few studies have been conducted to investigate the noise reduction characteristics of dense-graded asphalt pavement.
In this study, the influential factors of the noise reduction characteristics in laboratory compacted dense-graded asphalt mixtures are investigated first. An impedance tube experiment is conducted to analyze the sound characteristics of the mixtures. The effects of the nominal maximum aggregate size (NMAS), types of asphalt binders, and air void percentages on the noise reduction performance are studied. Here NMAS is measured specifically as one sieve size larger than the first sieve to retain more than 10 percent of the material. In addition, cored cylinder samples from three field pavements are also obtained to determine the effect of service life on noise reduction performance.