PURPOSES : In many European countries, the fine-size exposed aggregate concrete pavement (EACP) technique has been adopted for a quiet pavement. However, different noise reduction levels were reported based on the mixture design and texture conditions. This study aims to suggest a quality control condition for achieving low-noise texture and a mixture design procedure for exposed aggregate concrete overlay (EACO), which will provide the optimum mixture of the surface texture that can reduce the tire-pavement noise. METHODS : The tire-pavement noise is highly influenced by the pavement surface texture. The surface texture of the EACP can be quantified by the mean texture depth (MTD) and the exposed aggregate number (EAN). The optimum condition for the low-noise texture of the EACP was investigated herein based on the analysis of the review of the texture conditions and noise measurement in many EACP sites. RESULTS : The MTD and EAN criteria can be derived according to the investigated relationship between noise and texture condition. The optimum mixture design to satisfy these criteria can be achieved by controlling the maximum size of the coarse aggregate and the S/a. CONCLUSIONS: This study aimed to suggest a quality control condition for achieving low-noise texture and an optimum mixture design for EACO. As a result, we found that the early traffic opening of EACO can be achieved by using high early-strength cement.

PURPOSES : Almost every design method for airport concrete pavements considers only traffic loading and not environmental loading. This study proposes a mechanistic design method for airport concrete pavements, that considers both environmental and traffic loading simultaneously. METHODS: First, the environmental loading of concrete pavements in Korean airports was quantified. FEAFAA, a finite element analysis program for airport pavements, was used to calculate the maximum tensile stress (MTS) of the slab, caused by both environmental and traffic loadings. The factors that influence the MTS were identified via sensitivity analysis, and an MTS prediction model was developed using the statistical analysis program SPSS. The ratio of MTS to the tensile strength of slab was calculated using the prediction model. The fatigue model under the AC 150/5320-6E and AC 150/5320-6F standards of the FAA was corrected to make it suitable for the predicted stress-strength ratio. RESULTS : The MTS prediction model and corrected fatigue model were used to redesign the slab thickness and joint spacing of airport concrete pavements originally designed using the AC 150/5320-6D standard, which empirically considers traffic loading only. As a result, different slab thicknesses and joint spacings were redesigned with consideration for environmental loading, specifically the weather conditions of airports. . CONCLUSIONS: The slab thickness and joint spacing can be mechanistically designed at the same time, whereas previously, only the slab thickness was designed, and the joint spacing was determined empirically.

PURPOSES : As road pavement design in an apartment complex varies from one site to another, it is practically difficult to calculate and estimate the traffic volume of construction vehicles. Therefore, this study introduces a methodology to estimate the number of construction vehicles and use it as an indicator to evaluate the conditions of road pavement in an apartment complex. METHODS: Through a literature review and site survey, the operational status of the construction vehicles passing through the site was identified, and the factors affecting the number of construction vehicles were analyzed. The methodologies used to estimate the number of construction vehicles were verified by calculating the Cumulative Load Prediction Index (CLPI), which is a predictive index of the cumulative load on each path. By using this index, the traffic volume of construction vehicles can be estimated based on the number of households in an apartment complex. To prove this definition, we examined the surface and core conditions, and compared the results against the predicted values. RESULTS : By comparing the Cumulative Load Prediction Index with the crack rate on the pavement surface, we obtained a correlation coefficient of 0.92. Furthermore, the analysis indicated that the core condition rate would decrease as the Cumulative Load Prediction Index increased. This correlation between the Cumulative Load Prediction Index, and the pavement surface and core status demonstrates that the traffic volume can be estimated by considering the number of households. CONCLUSIONS: The Cumulative Load Prediction Index presented in this study is a suitable indicator for estimating the conditions of the road pavement in an apartment complex by considering the number of households in the complex, even if the construction processes and characteristics vary.

PURPOSES : In Korea, asphalt overlay has been used as a typical alternative rehabilitation method for deteriorated pavements. However, asphalt overlay has problems due to poor bonding of the asphalt overlay and the old concrete. Recently, concrete overlays, which have advantages such as long-term durability and high structural capacity to carry heavy traffic, have been considered for rehabilitation construction. However, concrete overlays have limitations such as difficulty in opening to traffic and pavement noise. Recently, an appropriate fine-size exposed aggregate concrete pavement technique was reported to solve these problems. Therefore, this study aims to suggest an optimum mixture design of fine-size exposed aggregate concrete overlay (EACO) that can ensure low noise and early strength. METHODS : The optimum mixture design of fine-size EACO is determined to ensure adequate structural performance for early traffic opening and good functional performances such as low noise. Therefore, the optimum mixture proportion is determined based on the optimum design of aggregate content to produce a low-noise pavement texture by controlling the exposed aggregate number (EAN) and mean texture depth (MTD). RESULTS : The water-cement ratio and unit cement ratio were used to determine the mixture designs to achieve workability and adequate strength for early traffic opening. The texture was determined by selecting the maximum size of coarse aggregate smaller than 10 mm with an S/a ratio of less than 30% for low noise. With these mixture proportions, the EAN and MTD were 50±5 / 25cm2 and 1.0±0.2 mm. Respectively, which meet the criteria for EACO. CONCLUSIONS: In this study, an optimum mixture design of EACO for early traffic opening and low noise is suggested by using earlyhigh strength cement, and the pavement texture is implemented considering EAN and MTD. In addition, a pavement surface texture criterion is suggested for the quality control of EACO.

PURPOSES : The objective of this study is to develop a simple regression model in designing the asphalt concrete (AC) overlay thickness using the Mechanistic-empirical pavement design guide (MEPDG) program. METHODS: To establish the AC overlay design equation, multiple regression analyses were performed based on the synthetic database for AC thickness design, which was generated using the MEPDG program. The climate in Seoul city, a modified Hirsh model for determining dynamic modulus of asphalt material, and a new damaged master curve approach were used in this study. Meanwhile, the proposed rutting model developed in Seoul city was then used to calibrate the rutting model in the MEPDG program. The AC overlay design equation is a function of the total AC thickness, the ratio of AC overlay thickness and existing AC thickness, the ratio of existing AC modulus and AC overlay modulus, the subgrade condition, and the annual average daily truck traffic (AADTT). RESULTS: The regression model was verified by comparing the predicted AC thickness, the AADTT from the model and the MEPDG. The regression model shows a correlation coefficient of 0.98 in determining the AC thickness and 0.97 in determining AADTT. In addition, the data in Seoul city was used to validate the regression model. The result shows that correlation coefficient between the predicted and measured AADTT is 0.64. This indicates that the current model is more accuracy than the previous study which showed a correlation coefficient of 0.427. CONCLUSIONS: The high correlation coefficient values indicate that the regression equations can predict the AC thickness accurately.

PURPOSES : One of the main components of road projects funded by the Economic Development Cooperation Fund (EDCF) is the improvement or rehabilitation of existing pavements. The result is that pavement structures are critical to the success of a project. There is, however, no design standard available at present that reflects a region's specific features including climate conditions and quality of pavement materials. For this reason, a comparative study of the major EDCF borrowers' flexible pavement design standards was conducted. This study led to the proposal of a new method for applying flexible pavement designs which can be used for EDCF-funded projects in Asia. METHODS : The method has been produced by adjusting some input data of the "AASHTO Interim Guide for Design of Pavement Structures" in accordance with certain Asian countries' geometrical features, tropical and subtropical weather, and strength of pavement materials. The Philippine regional factors, having five different grades, have been selected after taking into consideration the amount of rainfall, strength of pavement materials, and characteristics of the Asia and Pacific regions. Structural layer coefficients have been prepared for two different regions according to the geometric difference between Southeast and Southwest Asia. The Philippine and Sri Lankan coefficients have been used for Southeast Asia and Southwest Asia, respectively. CONCLUSIONS : Owing to applying this new method, it was verified that the thickness of the pavement was underestimated by between 11 cm and 16 cm compared with the originally designed thickness. Having discovered that the use of the Korean and Americanoriented factors and coefficients is not appropriate for other Asian countries, the new method is expected to enhance the quality of pavement in future projects.

최근에는 도심지 개발에 따른 지표면 포장률 증가로 인해 불투수면적의 증가하여 지하수의 고갈, 도시형 수해 증가 등의 문제가 발생하고 있다. 투수성 포장기법은 대표적인 저영향개발적용 기술 중 하나인 친환경 포장 공법으로 물순환 체계의 개선을 통한 환경 개선 효과와 더불어 차량 주행소음의 감소, 열섬 현상 완화, 미끄럼 저항의 향상 등 다양한 기능을 얻을 수 있으며 국내외 관련 연구가 활발히 진행되고 있다. 현재 일반도로는 한국형 포장설계법을 적용하여 설계를 하게 되어 있으나, 현재 투수성 아스팔트 도로를 설계를 위한 지침은 제시되어 있지 않다. 이에 본 연구에서는 국내외 선행 연구 조사 및 검토를 통해 투수성 아스팔트 포장 설계인자 및 구조 설계방법을 제안하고자 한다. 선행 연구 조사 결과, 투수성 포장 구조설계는 AASHTO 1993 설계법을 적용하여 수행하고 있는 것으로 확인되었다. 투수성 포장 설계인자 중 투수성 아스팔트 포장재료의 상대강도계수를 제안하였고, 한국형 설계법에서 고려하고 있는 도로설계등급을 고려하여 교통량 산정하는데 적용하였다. 또한, 투수성 콘크리트 포장설계를 위한 지지력 복합계수를 한국형 설계법에서 적용한 방법을 활용하여 구조 설계에 고려하였다. 이러한 설계인자를 고려하고 경제성을 고려한 최적 포장 두께를 산정하기 위한 최적화 알고리즘을 적용설계를 할 수 있는 PerPaveDesign 프로그램을 그림 1과 같이 개발하였다.

PURPOSES :This study proposes standards for rural access road pavement section and thickness design considering existing access road construction conditions; the study also proposes a complementary policy that can be used for design convenience.METHODS:Various literature review and case studies had been performed in terms of rural access road section and thickness design, both domestically and internationally, and this was followed by domestic rural access road field surveys. KPRP and KENLAYER were used to analyze the commonalities and predict the remaining life. Data on real cost is used to select an appropriate construction method through economic analysis.RESULTS:The economic efficiency of concrete pavement (15×15) was the highest in terms of economic efficiency of performance life and traffic volume. In the case of asphalt pavement, it is considered that the most economical method is to implement micro-surfacing method four times as a preventive maintenance method (once every 10 years and 4.5 years for asphalt concrete pavement and MS construction method, respectively). Repairable asphalt pavement is advantageous for areas where heavy vehicles are expected to pass. In the case of other general areas, it is considered economical to place concrete (15×15) pavement. However, as analytical results on its performance life are unavailable, it is to be considered for study in the future.CONCLUSIONS :This study proposed interim design guidelines based on various domestic and international design guidelines and case studies. However, in order to develop the final design criteria applicable to the field, it is necessary to (a) estimate the bearing capacity of the lower level of the pavement at various sites, (b) estimate the daily traffic volume, (c) implement advanced low-cost pavement technologies, and (d) propose maintenance standards and techniques for long-term performance.

지난 수십 년간 공공시설 및 사유지 적용을 위한 롤러전압콘크리트포장의 사용실적은 꾸준히 증가 하고 있는 추세이다. 롤러전압콘크리트포장은 아스팔트포장의 시공특성과 전통적 콘크리트포장의 재 료적 특성을 동시에 나타낸다. 또한 작업성(workability)과 다짐성(compactibility)은 롤러전압콘크 리트포장의 우수한 배합설계를 결정하기 위한 주요요소로써, 강도가 충분히 확보된 콘크리트라 할지 라도 적정 반죽질기 또는 작업성이 확보되지 않으면 시공이 용이하지 않을 수 있다. 일반적으로 포장 적용을 위한 롤러전압콘크리트의 배합설계 시 흙다짐 방법 및 반죽질기 방법을 사 용하고 있으나, 흙다짐 방법의 경우 작업성을 고려하지 못하며 반죽질기 방법은 작업성만을 고려하고 있다. 이에 본 연구에서는 포장 적용을 위한 롤러전압콘크리트에 대하여 실내실험 변수와 현장 공용성을 모두 만족시키는 배합설계방법의 개선방안을 제안하였다. 이를 위하여 실내실험 변수를 현장 공용성 으로 연계하여 적정 공용성을 확보할 수 있는 최적 롤러전압콘크리트 배합을 도출하였으며, 롤러전압 콘크리트의 주요 물성인 반죽질기, 강도 및 내구성과 배합비 간의 상관관계를 규명하기 위하여 다양 한 실내실험을 진행하였다. 또한 실제 현장 조건에서 이와 같은 물성들을 연계시키기 위하여 속초인 근 고속도로 부체도로에 총 5개 구간의 롤러전압콘크리트포장을 시공하여 품질관리 변수인 반죽질기 에 근거하는 하중지지력과 표면 물성에 대하여 조사하였다. 이와 같은 물성들의 새로운 이해는 포장 적용을 위한 롤러전압콘크리트의 배합설계절차 개선으로 이어진다.