Proceedings of Meetings on Acoustics

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1 Proceedings of Meetings on Acoustics Volume 15, rd Meeting Acoustical Society of America/ACOUSTICS 2012 HONG KONG Hong Kong May 2012 Session 1aNSc: Noise 1aNSc2. Noise-reducing asphalt rubber surfaces in China George Way, Jorge Sousa, Rongji Cao and Krishna P. Biligiri* *Corresponding author s address: Center for Infrastructure, Sustainable Transportation and Urban Planning, Indian Institute of Science, Bangalore, , Karnataka, India, krishna@cistup.iisc.ernet.in In the earlier part of 2004, the state-of-the-art and practice of asphalt-rubber (AR) surfaces as used and applied in the United States of America (USA) to reduce traffic noise was presented in China. AR surfaces have been used in the USA for many years to reduce the traffic noise. The AR surfaces can be applied as the final wearing course on conventional concrete and/or asphalt pavements. In the USA, the States of California and Arizona, and several others have successfully employed thin wearing courses (12.5 to 40 mm) of AR to reduce highway noise. Following this early exposure to the AR technology, China began to experiment and later used AR to reduce noise, as well as to provide a durable and good quality skid resistant wearing courses. This paper reports the progress of use of AR in China and the noise data from various surfaces in China. These surfaces included Stone Mastic Asphalt, Polymer Asphalt, Asphalt Rubber Asphalt Concrete and Asphalt Rubber Open Graded Friction Course. Published by the Acoustical Society of America through the American Institute of Physics 2013 Acoustical Society of America [DOI: / ] Received 2 Aug 2012; published 31 Jan 2013 Proceedings of Meetings on Acoustics, Vol. 15, (2013) Page 1

2 1. Introduction In the United States, Asphalt-rubber (AR) began to be used as an asphalt modifier in the State of Arizona in the late 1960s. In 1978, it was patented by two asphalt supplier companies in Arizona [1]. In 1994, American Society for Testing and Materials (ASTM) International established two standards that define and specify AR [2, 3]. The ASTM defines AR as a mixture of at least 15% ground tire rubber derived from scrap tires and 75% hot paving grade asphalt (bitumen). The Arizona Department of Transportation (ADOT) began using AR binder as a chip seal coat binder in the 1970s [4]. Later in the 1980s, the City of Phoenix, Arizona began using a hot mix with AR binder. This hot-mix was called an AR gap graded mix Asphalt-Rubber Asphalt Concrete (ARAC). Also in the 1980s, the ADOT developed an open graded hot mix using AR as the binder [5] and called this mix an Asphalt-Rubber Friction Course (ARFC). Both of these mixes (and gradations) shown in Figure 1 reduced the tire/pavement noise to such a degree that both City of Phoenix and ADOT conducted research studies to document the degree of tire/pavement noise reduction [6]. Starting in 1985, the ADOT began the construction of an extensive network of new freeways to serve the Phoenix metropolitan area. This new freeway system consists of new and older widened concrete pavements encompassing hundreds of kilometers. In the process of widening the older concrete pavements, an ARFC surface 25 mm in thickness was placed as the final wearing surface for reasons of improving the concrete smoothness, skid resistance and to facilitate the re-stripping of the freeway. As this construction proceeded, the citizens of the greater Phoenix area noted how much quieter the ARFC surface was in comparison with the concrete pavement surface. As a result of public recognition of the degree of noise reduction due to the ARFC, the ADOT developed a new program called the Quiet Pavement Program (QPP) wherein all of the concrete pavements in the Phoenix freeway system were immediately overlaid with an ARFC surface before opening to traffic [7]. 2. Measuring tire/pavement noise Since both the City of Phoenix and the ADOT noted tire/pavement noise reduction due to either an ARAC or ARFC surface [6, 8], it became very important to develop a method to accurately measure tire/pavement noise. Starting in the 1990s, the ADOT began to research and investigate how to measure tire/pavement noise. Initially the ADOT built an open air trailer with a microphone mounted closer to the tire. Later, the ADOT constructed a close proximity trailer which measured the tire/pavement noise inside of an enclosed trailer and discussions ensued with California colleagues to perform noise measurements. It was determined that an On Board Sound Intensity (OBSI) method of measuring the tire/pavement interface noise appeared to be the best and most practical method of measurement [8]. Figure 2 shows the chronology of noise measurement devices employed by the ADOT. As a result of the interest expressed by the ADOT, a joint research study was begun in 2004 by both Arizona and California to measure the tire/pavement noise using OBSI technique on a wide range of pavement surfaces. Based on the results of that study [9], a graph of the OBSI noise measurements versus pavement type was developed as shown in Figure 3. These measurements clearly showed that the ARFC surface was the quietest with a value of 96.6 dba. Likewise, the ARAC surface also exhibited a very good tire/pavement noise value of 97.2 dba. In 2004, a seminar on AR was held in Beijing, China [10]. This seminar introduced the benefits of using AR in a chip seal coat and as a hot mix, either gap or open graded. From this seminar, an interest was generated to use AR in China. Proceedings of Meetings on Acoustics, Vol. 15, (2013) Page 2

3 GRADATION DESIGN RECORD SIEVE SIZES RAISED TO 0.45 POWER (a) GRADATION DESIGN RECORD SIEVE SIZES RAISED TO 0.45 POWER (b) Figure 1 Arizona Mixture Designs: (a) Marshall Mix Gradation for Hot Mix Asphalt (conventional) and Gap Graded Asphalt-Rubber Mixes; (b) Open Graded (conventional) and Asphalt-Rubber Open Graded Mixes Note: VMA or Voids in Mineral Aggregates are the inter-granular space occupied by asphalt and air in a compacted asphalt mixture Proceedings of Meetings on Acoustics, Vol. 15, (2013) Page 3

4 Figure 2 Arizona Tire/Pavement Measuring Devices Figure 3 Arizona and California Tire/Pavement Measurements for Various Surfaces Proceedings of Meetings on Acoustics, Vol. 15, (2013) Page 4

5 3. AR in China As China s economy has grown so has the number of scrap tires. In 2004, China produced about one hundred million scrap tires per year and by 2010, the amount had increased to three hundred million scrap tires per year. In the 1980s, there had been some test trials of using scrap tire in a dry form in a dense graded hot mix. Later by 2004, experiments began on using both dry and the wet process of AR. From 2004 to 2007, many experimental test sections and test projects were constructed using AR as a chip seal coat interlayer referred to as a stress absorbing membrane interlayer (SAMI). Also, test sections of ARAC hot mixes were constructed; both the SAMI and ARAC test sections closely approximated the materials placed in Arizona and California. From 2007 until now, the use of AR in the wet process similar to one used in the US has grown, as shown in Figure 4. Implementation of AR as a hot mix or seal coat has reached over 20 provinces in China [11]. Additionally, specifications and guidelines for AR are becoming more common in China [12-16]. An International conference on AR and its applications was held in Nanjing, China in 2009 where the use of AR in China was widely disseminated [17]. Figure 4 Use of AR in China 4. China tire/pavement noise measurements Now that the use of AR is becoming more common in China, attention has turned to measuring the tire/pavement noise of various pavement surfaces. Although the use of AR is still relatively new in China, the measurement of tire/pavement noise is also in the developmental stages. It is noteworthy that Jiangsu province in China measured the tire/pavement noise of various surfaces as previously done in Arizona and California. Table 1 represents the first effort within China to measure the tire/pavement noise using the OBSI method [18]. As shown in the Table, the pavement surfaces constructed with either ARFC or ARAC demonstrated very significant tire/pavement noise reduction. Proceedings of Meetings on Acoustics, Vol. 15, (2013) Page 5

6 Table 1 OBSI Noise Measurements Performed in China, 2009* *All measurements in Discussion AR use in China is just in the beginning stages as compared to the US where AR has been in use as a chip seal coat since the 1970s and as an ARAC and ARFC mix since the 1980s. It appears that China will use AR and its applications to best fit its materials and environment. Although the use of AR has the quality of reducing the tire/pavement noise, the material also has many other benefits, including: reducing cracking, and improving durability. With proper design and construction, AR mixes can provide very smooth riding surfaces with very good skid resistance and low splash and spray, which can translate to fewer accidents [5]. It should be noted that no AR pavement surface has been designed to reduce tire/pavement noise, but rather the use of AR in ARFC and ARAC mix designs produces low noise surfaces as an important functional benefit. Research is needed to develop a design method to produce mixes with a predictable noise reduction quality. It is anticipated that China will partake actively in such research activities to develop a rubber-type surface of even superior noise-reducing qualities. Proceedings of Meetings on Acoustics, Vol. 15, (2013) Page 6

7 References [1] Heitzman, Michael A., State of the Practice Design and Construction of Asphalt Paving Materials with Crumb Rubber Modifier, Federal Highway Administration, FHWA-SA , May [2] ASTM D8, Standard Terminology Relating to Materials for Roads and Pavements, American Society for Testing and Materials, American Society for Testing and Materials International Standards Worldwide, Volume 04.03, Road and Paving Materials; Vehicle-Pavement Systems, [3] ASTM D6114, Standard Specification for Asphalt-Rubber Binder, American Society for Testing and Materials, ASTM International Standards Worldwide, Volume 04.03, Road and Paving Materials; Vehicle-Pavement Systems, [4] Scofield, L. A., The History, Development, and Performance of Asphalt-rubber at ADOT, Report Number AZ-SP-8902, ADOT, December [5] Way, George B., Kamil Kaloush., and Krishna P. Biligiri, Asphalt-Rubber Standard Practice Guide, Rubber Pavements Association, USA, 2011 Edition. [6] Scofield, L., Development of Arizona s Quiet Pavement Research Program, Asphalt rubber 2003 Proceedings, Brasilia, Brazil, December 1-4, 2003, ISBN [7] Arizona Department of Transportation, Quiet Pavement Program, December [8] Gruner, J. R. and A. J. Assaf, Sound Level Survey, Phoenix, Arizona, Western Technologies Inc., April [9] Zareh, A., George B. Way., and Kamil E. Kaloush, Asphalt-Rubber open graded mix reduces tire pavement noise, Asphalt rubber 2006 Proceedings, Palm Springs, California, October 25-27, 2006, IBSN: [10] Way, George B., and Jorge Sousa, Seminar on Rubber Modified Asphalt and AR Mixture, Beijing, China, July [11] Cao, Rongji, Asphalt Rubber in China, Rubber Pavements Association Meeting, Maui, Hawaii, January [12] Tianjin Construction Commission, Technical Specification of Waste Tire Rubber Powder Modified Asphalt Pavement, In Tianjin, [13] Jiangsu Expressway Construction Bureau, Construction Guide for Asphalt Rubber Pavement, [14] Beijing Highway Bureau, Design and Construction Guideline of Crumb Rubber Asphalt and Mixtures, [15] Road Research Institute of Highway MOT, China, Design and Construct Guide for Asphalt Rubber and Mixtures, [16] MOT, China, Specification for Asphalt Rubber. [17] Zareh, A., Douglas D. Carlson., and George B. Way, Asphalt-Rubber Open Graded Friction Course Reduces Noise - The Quiet Pavement Program, AR2009 Conference Proceedings, Nanjing, China, November 2-4, 2009, pp , ISBN: [18] Cao, Rongji, communication from Cao to George Way, regarding China OBSI measurements, February Proceedings of Meetings on Acoustics, Vol. 15, (2013) Page 7