PURPOSES : This study aims to reduce the urban heat island phenomenon via utilization of porous asphalt pavements. METHODS : One of the many known functions of porous asphalt is that it reduces the urban heat island phenomenon. Indoor experiments were conducted to compare the surface temperature of sprinkled dense-graded and porous asphalt and outdoor experiments were conducted to verify the difference between the two asphalt pavements under external conditions. RESULTS : The results of the indoor experiment demonstrated that the temperatures of the two pavements were similar and that the porous asphalt pavement exhibited low temperature when sprinkled; the temperature of the porous asphalt was approximately 2 °C lower than that of the dense-graded asphalt pavement. The results of the outdoor experiment showed that the peak temperatures of the two pavements were approximately the same as usual. However, it was confirmed that the surface temperature of the porous asphalt pavement at night after sunset was lower than that of the dense-graded asphalt pavement and that the peak temperature dropped for approximately 1~2 days after the rainfall.. CONCLUSIONS : Porous asphalt pavement has a lower surface temperature than normal dense-graded asphalt pavement, under the presence of moisture in the pavement. In addition, it was confirmed that the lower surface temperature of the porous asphalt pavement is due to the low heat emission of the pavement at night. Accordingly, it is believed that the application of the porous asphalt pavement will not only have known effects but also significant impacts on the reduction of urban heat island phenomena.

PURPOSES : The objective of this study is to address various problems, such as an increase in material cost and premature failure (e.g., cracks and potholes) of porous pavements, and to develop multifunctional asphalt and asphalt mixtures to ensure the long-term commonality of porous asphalt pavements. METHODS : A basic quality test of two types of porous asphalt mixtures was performed. One type consisted of the existing porous asphalt mixture, using domestically presented grading, and the other a porous asphalt mixture using high-viscosity modified asphalt with enhanced low-temperature properties, aimed at improving strain resistance and developed by applying the grading suggested by the Federal Highway Administration (FHWA). RESULTS : The cantabros loss rate was 19.62 % for conventional modified asphalt (PG 82-22) and 5.95 % for the developed highviscosity modified asphalt (PG 88-28), indicating that both mixtures passed the criteria. Regarding the drain-down loss rate, mixtures using both types of asphalt were found to pass all quality standards. The average permeability coefficients for each porous asphalt mixture were 0.023 and 0.018 and both types of porous asphalt mixtures satisfied the quality standard of 0.01 cm/s, as given by the Asphalt Concrete Pavement Guidelines of the Ministry of Land, Infrastructure, and Transport. CONCLUSIONS : As a result of the mix design of the two porous asphalt mixtures, the mixture developed in this study was found to be superior to the conventional porous asphalt mixture using conventional porous asphalt grading and modified asphalt.

PURPOSES : In this study, noise reduction effect of a two-layer porous asphalt pavement was investigated through site measurement and computer simulation. METHODS: To examine noise reduction effect, a 3 km long quiet pavement was installed by removing previous normal pavement, which had a rather low porosity. The studied site was a high-rise apartment building surrounded by the quiet pavement and Seoul ring road with heavy traffic volume, indicating relatively high background noise. RESULTS: The measurement result before and after installing the quiet pavement showed a noise reduction effect of 4.3 dB(A) at a distance of 7.5 m from the road. After validating the accuracy of simulation using SoundPLAN, the reduction in SPL(sound pressure level) at the facades by the quiet pavement was predicted by considering five different road conditions generating traffic noise from each road or in the combination of the quiet pavement and Seoul ring road. In the case of no noise from Seoul ring road, noise reduction at the facades was 4.2 dB(A) on average for 702 housing units. With background noise from Seoul ring road, however, the average SPL decreased to 2.0 dB(A). Regarding subjective response of noise, the number of housing units with a noise reduction of over 3 dB(A) was 229 out of 706 units (approximately 32%). For 77 housing units, the noise reduction was between 1~3 dB(A), while it was less than 1 dB(A) for 400 housing units. CONCLUSIONS: The overall result indicates that the quiet pavement is useful to reduce noise evenly at low and high floors compared to noise barriers, especially in the urban situation where background noise is low.

PURPOSES : This study is to construct the regression models of drainage asphalt concrete specimens and to provide the appropriate coefficients of hydraulic conductivity prediction models. METHODS: In terms of easy calculation of the hydraulic conductivity from porosity of asphalt concrete pavement, the estimation model of hydraulic conductivity was proposed using regression analysis. 10 specimens of drainage asphalt concrete pavement were made for measurement of the hydraulic conductivity. Hydraulic conductivity model proposed in this study was calculated by empirical model based on porosity and the grain size. In this study, it shows the compared results from permeability measured test and empirical equation, and the suitability of proposed model, using regression analysis. RESULTS: As the result of the regression analysis, the hydraulic conductivity calculated from the proposal model was similar to that resulted from permeability measured test. Also result of RMSE (Root Mean Square Error) analysis, a proposed regression model is resulted in more accurate model. CONCLUSIONS: The proposed model can be used in case of estimating the hydraulic conductivity at drainage asphalt concrete pavements in fields.

본 연구는 배수성 아스팔트 포장에 사용하기 위하여 국내에서 개발한 개질 아스팔트 바인더 및 혼합물의 실내 및 현장 공용성을 평가한 연구이다. 국내에서 개발된 개질 아스팔트 2종에 대한 DSR, BBR 및 다양한 바인더 시험을 실시하여 공용성능이 상대적으로 우수한 1종의 개질 아스팔트를 선정하였다. 선정된 개질 아스팔트와 기존에 일본에서 사용되는 개질 아스팔트를 사용하여 각각에 대하여 배합설계를 실시하고, 배수성 아스팔트 혼합물을 생산하여 실내 공용성을 비교하기 위해 휠트래킹 시험, 수분손상 시험, 피로시험 등을 수행하였다. 그 결과, 공용특성 측면에서 국산의 개질 아스팔트가 일본 개질 아스팔트와 비슷하거나 경우에 따라서는 우수함을 확인하였다. 실내시험결과를 바탕으로 현장 시험시공을 실시하였고, 추적조사를 통하여 시간에 따른 공극률과 소음특성의 변화를 측정하였다. 그 결과 시공 초기에는 배수 및 소음 저감 능력이 우수하였으나 2년이 경과한 후 소음 저감 능력이 감소하여 SMA 포장과 비슷한 수준의 소음저감효과를 나타내었다.

높은 포장온도는 아스팔트포장 소성변형의 주요인이나 소성변형을 줄이기 위한 방안으로서 포장온도를 줄이는 측면에서는 아직 많은 연구가 이루어지지 않은 실정이다. 본 연구에서는 소성변형결함을 줄이기 위한 하나의 대안으로, 온도저감 효과가 있는 것으로 알려져 있는 보수성 포장을 배수성 포장의 하부층에 설치한 포장의 공용특성을 연구하였다. 본 연구의 목적은 보수형 배수성 포장의 온도저감효과를 정량화하고, 포장가속시험(Accelerated Pavement Testing)을 이용하여 온도 저감에 따른 소성변형 감소효과를 확인하고, 정량화하는데 있다. 또한 추가적으로 보수성 포장의 상대강도계수를 분석하고, 일반 포장과 비교하여 설계법 적용시 포장두께를 줄일 수 있는지 여부를 알아보고자 하였다. 본 연구를 위해 보수형 배수성포장 2개 단면 및 일반 배수성 포장 1개 단면 등 총 3개 시험구간이 시공되었다. 히팅 및 살수를 일정주기로 실시하였으며 하중조건은 윤하중 8.2ton, 타이어 공기압 7.03kgf/cm2 타이어 접지면적 610cm2이었다. 이 연구에서 포장체 온도저감효과는 중간층의 경우 6.6~7.9℃(평균7.4℃), 표층의 경우 7.9~9.8℃(평균 8.8℃)였으며, 이를 통해 포장표면의 소성변형 발생을 26% 감소시킬 수 있었다. 또한 탄성계수로부터 추정된 보수성 포장의 상대강도계수는 0.173으로 일반 밀입도 포장의 1.2배 정도였으며, 일반배수성 포장 구간에서는 표층, 중간층, 기층 모두 소성변형이 발생한데 반해 보수형 배수성 포장 구간에서는 표층에서 대부분의 소성변형이 발생된 것으로 나타났다.

Surface fog coating methods to porous pavements with a polymer, that contains MMA as a main ingredient, are being widely used in Japan and called 'Top-Coat Processes'. They have lots of effects such as to prevention of the pavement void choking, improvement of the water permeability of the pavements and so on. The purpose of this research is to show the characterization of the polymer to optimize the functions of the polymer fog-coat methods. This study focused on the difference of 'wetting' by water among polymers used for the fog coatings, and calculation the surface free energy from the water contact angle on each material. At the end, the water permeability test were conducted using porous asphalt mixtures that were coated with several kinds of polymers. The permeability was also measured on the specimens that were forcibly choked by muddy water and the resistance to choking was compared. It is concluded that the reduction of the surface free energy between water and a polymer improves the life of the permeability functions of porous pavements. Improvement of water permeation capacity and void-blocking controlling effects can be quantitatively evaluated using the interfacial tension (γsl) with water for the coating material (high-viscosity asphalt and hardening resin binder). Consequently, the smaller the γsl of the coating material the higher the water permeation capacity and void-blocking controlling effects of the porous asphalt pavements.

Improving traffic capacity and vehicle speed is no longer the main focus in transportation because of developments of technology and awareness of the citizens. Therefore, transportation's focus has been changing to solve social and environmental phenomena, such as noise and accident reduction and disaster prevention. One of new solutions that solves transportation problems is porous asphalt concrete pavement that can reduce highway noise and accident in wet condition. This research evaluated the economic characteristics of porous asphalt pavements by selecting associated safe and environmental variables. Also, The research conducted economic analysis between porous pavements and traditional pavements. The results show economic benefits of porous pavements.