burn.
Dap
Fuel oil evaporating through the voids of the pavement ignited, causing blue flames. However, pavement materials did not
burn.
Pers
Fuel oil evaporating through pavement voids ignited; rubber panels burned up, causing reddish flames. Fire spread over the pavement very slowly.
1.0-1.5 m
A column of black smoke was observed from the burning rubber panels.
Approximately 0.3 m Only a little smoke
was observed.
3. F irst test construction
PERS construction in highways requires the structure to be developed as a total
pavement system and a construction method that is very different from the previous ones in PWRI test courses. There are two reasons for improving the structure and construction method.
The first one is a time constraint. One potential application of PERS is for
heavy-traffic arterial highways in urban areas, where the working time is limited to 10 hours at night (such as from 8 PM to 6 AM) to avoid causing traffic congestion. The standard area of pavement resurfacing of an urban highway is 2,000-3,000 square meters per day. The construction work involves removing the existing wearing course & base course, constructing new semi-flexible pavement as the base course, putting adhesive on the base course, and paving PERS as shown in Figure 9(a). Considering the working time before paving PERS, it is impossible to complete all the works within the limit.
The second reason is for quality control of adhesive performance. In the early stage of development of PERS, there were various troubles concerning the adhesive as mentioned in the previous section. The polymer type of adhesive is very sensitive to the ambient conditions of curing such as temperature and humidity. It seems very difficult to maintain stable performance of the adhesive during outdoor work.
In response to these problems, pre-fabricated types of PERS would appear to be the only solution. The main pre-fabricated types of pavement products are Inter-Locking Block (ILB), Pre-stressed Concrete Panel (PCP), and Reinforced Concrete Panel (RCP). The ILB has been widely used for pedestrian ways especially in prestige areas and shopping malls, where architects and planners are interested in the visual impact of paving. Some ILBs are also to be found in industrial areas, such as storage yards and dock-side paving, where the main concerns are structural performance, cost and maintenance. The PCP is pre-tensioned in the transverse direction during fabrication, and post-tensioned together in the longitudinal direction after placement. The PCP and RCP are mainly used for sections where extremely high durability is required, such as the pavement in tunnels.
.
In view of the time constraints, it is impossible to use PCP and RCP as the base course of PERS because of the slow speed of construction of less than 100 square meters per ten hours. The present mechanical method of laying ILB improves the construction efficiency and overcomes the constraint. With this background, the author has proposed using ILB for the first test construction of PERS. However, ILB has been used in very few cases for highways and its durability for the surface course is unknown. The author has clarified the initial durability of the ILB-PERS composite surface by accelerated pavement tests in the laboratory shown in Figure 9(b). No fatal damage to the surface was found after 12,000 passes of the test truck.
PERS was first constructed at Tazawa of National Highway Route 46 on 18 October, 2002. The total number of lanes is two and the width of each is 3.75 meters. The total length is 20 meters. The traffic volume, heavy traffic ratio, and speed limit are 10,120 vehicles per day, 20%, and 60k m/h, respectively. Figure 10 shows the general view of the section and the initial condition of the PERS surface. The author measured the noise of individual vehicles by using a special method proposed by Meiarashi (1996). The vehicles were limited to smaller ones such as passenger cars and light trucks, because of the short section length. Figure 11 illustrates the arrangement of equipment, including a sound level meter as a microphone and two sets of photo-detectors as a speed meter. Figure 12 shows the A-weighted peak levels of vehicles measured at PERS and DENAP. When noise reduction levels are defined as the difference in levels between PERS and DENAP, they are approximately given by the formula: ΔPWL = 0.1V
4. Conclusion
The Public Works Research Institute (PWRI) has, since 1993, been developing a new low-noise pavement named “Porous Elastic Road Surface” (PERS). The author estimates that the potential noise reduction levels in Leq exceed 10 dB(A). The PWRI has already solved several of the problems with PERS such as insufficient adhesion between the pavement and the base course, low skid resistance, and poor fireproof
performance.
Based on the above research results, PERS was first constructed at the National Highway Route 46. Noise reduction levels measured in the field were less than expected, because the size of the construction area was very small.
The author will continue these investigations in the field and will attempt another test construction using a more efficient construction method than ILB .
References:
[1]Alan Lilley (1988): “Precast Concrete Paving History, Design, Applications and Problems”, The Journal of the Institute of Highways and Transportation, pp. 18-25 [2] David Merritt, B. Frank McCullough, and Ned H. Burns (2001): “Feasibility of Using Precast Concrete Panels to Expedite Construction of Portland Cement Concrete Pavements”, Transportation Research Record 1761, Paper No. 01-2904 [3]Meiarashi S, et al. (1996): “Noise Reduction Characteristics of Porous Elastic Road Surface”, Applied Acoustics, Vol. 47, No. 3, pp. 239-250
[4]Ulf Sandberg and Jerzy A. Ejsmont (2002): “Tire/Road Noise Reference Book”, INFORMEX Ejsmont & Sandberg Handelsbolag
多孔弹性路面将作为最终的高速公路隔音措施
Porous Elastic Road Surface as An Ultimate Highway Noise
Measure
S. MEIARASHI
先进的材料队，材料及岩土工程研究组，公共工程研究所，日本
mei@pwri.go.jp
摘要：在日本的市区公路交通噪音是一个严重的问题，不仅对公路沿线的居民，也对公路管理员。只有13 ％的城市公路已达到环境噪声标准。隔音板不能作为大多数出入不受控制的高速公路的隔音措施。一些城市的公路沿线地区的噪音水平超过15分贝（A）或以上的标准。这个问题是阻碍新的公路在城市地区的建设。多孔沥青路面最近已在日本的城市公路上采用。其噪音减少3分贝（A）的效果是不够的，因为它仅仅提高了噪声环境满意率几个百分点。此外，其降噪效果的耐久性通常差不多只有三年，这比其作为路面生命周期较短。
公共工程研究所（PWRI ） ，自1993年以来，一直在开发一个新的名为“多孔弹性路面”（PERS）的低噪音路面。这种新的路面具有多孔结构，由旧轮胎制成的剂橡胶颗粒作为其骨料与聚氨酯树脂作为其粘结组成，其孔隙率约为40 ％ 。这种路面设计在20世纪70年代在瑞典首次提出的，但是，瑞典的研究人员想改善它作为一种实用的路面的想法已经失败。降低汽车噪音水平15分贝（A）和卡车8分贝（A）。笔者估计， Leq值减少潜在的噪音水平超过10分贝（A） 。如果达到这个降噪水平那么超过90 ％的市区公路将符合标准。公共工程研究所通过多孔弹性路面已解决了几个问题，例如，路面和基层之间的附着力不足
，防滑性低，防火性能差。其技术水平已达到城市公路建设的试验阶段。
本文通过过去研究所的发展中检查到多孔弹性路面的一般表现。它还概述了最近进行的研究结果，以进一步提高多孔弹性路面的降噪水平，用于多孔弹性路面的测试建筑在日本第一次建成。任何类型的车辆的最终噪声减排目标是15-20分贝（A ）之间。笔者预计，多孔弹性路面可将日本的市区公路交通噪音问题减少到很小，甚至在不久的将来可以忽略不计的水平。 关键词：
路面，降噪，公路交通噪声，防滑性，耐久性，粘附 1．引言