도심부 도로에서 불투수면적 증가로 인해 발생한 홍수 및 물순환 장애 문제를 해결하기 위해, 투수블록포장이 도입되고 있으며, 물순환 시스템 강화의 필요성에 따라, 투수블록포장은 효과적인 대안으로 주목받고 있다. 투수성 포장의 성능 향상 을 위해서는 교통 하중 지지력을 만족하고, 투수 성능을 동시에 확보해야 하므로 표층뿐만 아니라 하부 투수기층의 설계 기준과 입도 특성에 대한 고려가 필요하다. 그러나, 국내의 경우 설계법이 잘 정립되어 있지 않고, 국외에서는 AASHTO 93 설계법을 구조설계법으로 적용하고 있으며, 투수성 포장재료의 상대강도계수에 대한 연구가 부족하여 다양한 재료에 대 한 설계 적용이 어려운 한계가 존재한다. 이에 본 연구는 투수블록포장 하부 투수기층 골재의 물리적 특성과 입도 기준에 관한 고찰을 통해, 내구성 향상을 위한 설계 요인과 투수 성능 간의 관계 분석 결과를 정리함으로써, 두 방향을 모두 고려하여 효율적인 골재 입도 구성을 도모할 수 있는 적합한 방향성을 정립하는 것을 목표로 한다. 다양한 투수성 포장 설계 조건과 성능에 관한 연구를 다루는 문헌을 수집해 투수 블록포장의 하부구조 단면 설계에 적용할 수 있는 기준 및 연구 방법론을 정리함으로써 실무 연구자들의 국내 연구 활성에 기여하고자 한다

단지 내 도로는 별도의 설계법 없이 AASHTO 및 TA 설계법, 한국형 도로포장 설계법을 적용하여 일률적인 포장 두께를 적용하고 있으나 비산먼지 방지 목적으로 중간층 또는 기층 포설 후, 공사차량을 사전개방하고 사업 준공 단계에서 표층을 시공하는 단계시공 을 실시하고 있다. 이에 의해 포장단면 두께는 공사차량의 영향으로 공용수명을 만족하지 못하게 되므로 포장 파손이 빈번하게 발생 하므로 이를 고려한 포장 설계법 정립이 필요하다. 따라서 공사차량 통행을 고려한 단지 내 도로포장 설계기준을 적용한 시험시공 구 간을 대상으로 현장 모니터링 조사를 수행하였으며, 구조해석 프로그램을 활용하여 단면두께에 대한 포장 공용수명을 산출함으로써 적정성을 검토하였다. 현장조사 결과, 표층 시공 후, 공사차량 교통량을 개방한 구간에서는 공용기간 48개월일 때 표면 균열율이 1% 미만으로 조사되었으며, 중간층만 포설된 단면에서 공사차량 하중이 재하되고, 표층을 포설한 구간의 균열율은 약 8%로 상대적으로 높게 나타났다. 일반적으로 균열율이 8% 초과할 경우, 노후화된 포장층으로 판단하여 유지보수를 실시(서울시, 2018)하므로 조기파손 이 발생한 것으로 제시할 수 있다. 또한, 기존 설계기준을 적용한 구간의 표면상태 조사결과와 KENPAVE를 활용한 Damage 산출 결과 가 유사한 추세로 나타났으며, 6,170 세대 이상의 공사차량이 통행할 경우 공용년수를 만족하지 못하였으므로 해당 세대수에 대해서는 상향 설계를 실시해야 한다. 유지보수 기준에 따라 5∼7년 동안 공용된 포장에서 나타나는 균열율을 기준으로 KENPAVE Damage 10%, KPRP 피로균열 6% 이하이면 10년 이상의 공용이 가능한 것으로 도출되었다. 그러나 절삭 후 덧씌우기를 진행하지 않은 포장 단면에서는 상대적으로 높은 표면 균열율이 발생하므로, 잔존수명 예측을 통해 적절한 절삭 깊이를 산출하여 목표 설계수명을 만족할 수 있는 단지 내 도로포장 설계단면의 적정 기준을 제시함으로써 공용수명을 향상시킬 수 있을 것으로 기대한다.

본 연구는 2011년에 개발된 한국형 포장설계법(KPRP)이 국내 도로포장 분야에서 어떻게 활용되고 있는지를 조사하며, 특히 JCP(적층 콘크리트 포장) 설계에 중점을 두고 다양한 해외 포장설계 프로그램과의 비교를 수행하였다. 이를 위해 AASHOTO Ware와 같은 국제적으로 인정받고 빈번히 활용되는 해외 프로그램을 선택하여 두 프로그램 간의 차이점을 파악하고자 했다. 비교 대상으로 선정된 AASHOTO Ware는 미국에서 개발된 프로그램으로, 차량 분류 및 기후데이터 활용과 관련하여 KPRP와는 다른 특징을 보인다. AASHOTO Ware는 차량을 16종으로 분류하는 반면, KPRP는 12종으 로 분류하며, 특히 화물차량에 대한 상세한 분류 기준을 가지고 있다. 또한, AASHOTO Ware는 실시간 기후데이터를 인터넷 기반으로 활용하는 반면, KPRP는 기상대에서 축적한 데이터를 사용한다. 두 프로그램 간의 Input 값은 기후데이 터와 교통량 데이터 중 차량 분류를 중심으로 비교하였다. 향후에는 AASHOTO Ware의 설계로직을 분석하여 더욱 세 밀한 비교를 진행하고, 두 프로그램의 설계 전이함수와 로직을 분석하여 KPRP 프로그램의 발전에 기여하는 것이 이 연 구의 최종 목표이다. AASHOTO Ware의 유연한 최종IRI값 설정과 상세한 차량 분류 기준은 KPRP의 발전 가능성을 탐 구하는 데 중요한 지표로 활용될 것으로 예상된다.

PURPOSES : A mechanistic-empirical (ME) predictive design logic that can compute the reflective cracking life of hot-mix asphalt (HMA) overlaid on top of a composite pavement is proposed herein. METHODS : The overlay thickness design and analysis logic of the HMA were formulated based on the ME concept of reflection crack propagation. Climate data, traffic load data, the pavement material properties, and the thickness of each layer of the pavement are the main inputs for the ME-Reflective Cracking Rate (RCR) prediction algorithm. An Microsoft Excel Virtual Basic for Application (VBA) program was created to aid designers in assessing the expected performance of an HMA overlay design. Calibration was done using data from the Long-Term Pavement Performance (LTPP) sections. Sensitivity analysis was conducted to compare the results yielded by the program and data from a report by the Texas Transportation Institute. RESULTS : The predictive model performance effectively generates the dynamic and relaxation modulus curves. The correlation value of the calibration factors, R2, is 0.79. The calibration factors used for the Asphalt Overlay Thickness Design (AOTD) program and the sensitivity analysis, i.e., k1, k2,, and k3,, are set to 5, 5, and 150, respectively. The sensitivity of the AOTD program affords reasonable results. Additionally, the program yields results similar to the trends presented in a report by the Federal Highway Administration. CONCLUSIONS : The proposed ME design logic is successfully translated into an Excel VBA program, AOTD, which can perform routine assessments of laboratory tests for HMA overlays. The program can effectively perform numerous iterations and computations to predict an HMA overlay. The predictive model can generate reasonable dynamic modulus and relaxation modulus curves for the characterization of HMA overlays. Under the same asphalt binder grade and HMA type, doubling the HMA overlay thickness yields three times the expected reflective cracking service life.

PURPOSES : This study evaluates the long-term performance of the asphalt overlay designed by the Seoul pavement design method which determines overlay thickness by considering existing pavement conditions, traffic volume, and bearing capacity of the pavement. METHODS : A total of 76 sections including 17 control sections and 59 design sections were constructed under various traffic conditions, overlay thicknesses and asphalt mixtures. The performance of the pavements has been monitored up to 60 months in terms of surface distresses, rutting, and longitudinal roughness. The service life of the pavements was estimated to be the period when the Seoul pavement condition index (SPI) becomes 6.0, i.e., a rehabilitation level. RESULTS : Overall, the service life of the pavements was 72 months in the control and 120 months for the design sections. For relatively thinner overlay sections than designed, the service life reduced significantly; 36 months for 15cm thick overlay and 120 months for 25cm thick overlay. The service life of the pavement in the bus-only lane was 78 months, which is 30 months shorter than that in mixed-traffic lanes. Out of the bus-only lanes, 56% of the pavement along bus stop was deteriorated early to be a poor condition while only 2% of the pavement in a driving lane was degraded to be poor. The overlay with Stone Mastic Asphalt (SMA) in the wearing surface had 38% longer life than that with conventional dense graded mixtures. CONCLUSIONS : Most of the overlays sections designed by the Seoul pavement design method were expected to survive 10 years, except for bus-only lanes. The control sections having 5 to 10 cm thick overlays showed significant lower performance than the design sections. Thus proper thickness and materials considering the characteristics of existing pavement and traffic volumes should be applied to secure the service life of overlays.

PURPOSES : This paper proposes a design framework for planetary road infrastructure by considering the characteristic environment, natural resource, and loading conditions on the Moon and Mars. METHODS : From the perspective of civil engineering, available literatures such as technical articles, NASA (National Aeronautics and Space Administration) Technology Roadmaps 2015, Strategic Knowledge Gap, and mechanistic-empirical pavement design method are comprehensively reviewed for planetary road construction. The concept of in situ resource utilization (ISRU) is re-interpreted by comparing ISRU on the Earth and Moon with emphasis on the significance of interconnection between resource utilization and infrastructure development. RESULTS : According to the literature reviews, the factors that have significant effect on planetary road pavement design, construction, and maintenance are selected and evaluated. In addition, by considering the interconnection issue, a design framework is suggested that includes the resource issues not only of planetary road pavement but also of construction equipment. Subsequently, the framework is widened to apply for preliminary planetary infrastructure. CONCLUSIONS : Although the proposed preliminary design framework is not conclusive and has to be elaborated, an initial framework to consider interconnection issues and ISRU is suggested for planetary road pavement. The suggested framework will be applied for road pavement design and will be used to evaluate the cost-benefit ratio of alternatives.

In this paper the authors would like to present and share the measurements of load spectra and their modelling for pavement design purposes in the Mexican road network, which due to the intense level of trade with the United States present a very high percentage of heavy vehicles in the flow of vehicles and with high levels of load. Examples of these measurements are given in the country's main transport corridors. Damage spectra are also presented that are associated to each of the different axle types (i.e., single, dual, tandem, tridem or another one) by computing for instance the Miner damage coefficient in the same load ranges used in the definition of the load spectra. Is this frequency distribution of the Miner damage coefficient that is called damage spectra. The damage spectra seem to be a very useful tool to evaluate the pavement expected damage, i.e., rutting or fatigue cracking, induced for a given axle type. Moreover, it can be showed that there is a direct relationship between the forms in load and damage spectra. Some examples are presented to illustrate the damage spectra computations. The incorporation of these load spectra into mechanistic design methodologies and their implications in the definition of public policies for the preservation of the road network are discussed.

In recent years there has been an increased number of cases where geogrid have been incorporated into unbound road base layers to promote roadway optimization. The term optimization in this context refers to the use of geogrid to form a mechanically stabilized base course layer which leads to an improved performance of unbound layers by controlling particle movement and reducing permanent deformations. A mechanistic based pavement design approach offers a better means to accommodate the geogrid effect within the pavement structure. Guidance published by AASHTO recommends that pavement designs incorporating the effect of a geosynthetic need to be based upon experimentally derived input parameters. Performance data obtained from full scale accelerated pavement test studies and monitored field trials can be used to determine the influence of a geogrid on performance over the life of the pavement. This paper will highlight the concept of pavement optimization and present several cases where both post construction and long term evaluation methods were utilized in the quantification of the effectiveness of geogrid stabilized pavement structures.

Historically, the two major aspects of road design have been (i) The design principles – like AASHTO 1993 Empirical Design or lately, Mechanistic Empirical Pavement Design Method (MEPDM) (ii) The materials & technologies of pavement construction The fundamental design principles have not undergone major changes, however, the advancement in materials and technologies have improved tremendously over last few decades and this makes it necessary to revisit some of the conventional concepts in road design. The new technology now challenges the conventional wisdom and has brought us to the threshold of an era of all new sustainable green roads of tomorrow. AASHTO 1993 Empirical Pavement Design is the basis for pavement design today; in most parts of the world. In some parts of the world, there is a movement towards Mechanistic Empirical Pavement Design Guideline (MEPDG), but the movement is slow and gradual as this approach is expensive and heavily dependent on software programs due to its inherent computational complexities. The concept of Structural Number and Layer Coefficients of pavement layers under AASHTO 1993 Empirical Pavement Design was derived from AASHO road test carried out in Ottawa, Illinois between 1958 & 1960. The conventional Layer Coefficient value of 0.44 which is used today was recommended considering the strength of the construction materials available at that time. But, in view of the new technology available now, this needs to be revisited. Secondly, AASHTO 1993 Empirical Pavement Design provides for assuming certain values for Drainage Coefficients, ranging between 0.4 to 1.4, based on certain criteria. It is quite common to assume a value of 1 for drainage coefficient, in most parts of the world. Now, with the advent of new nanotechnology for waterproofing of road layers, it is possible to consider higher values for drainage coefficients. The new nanotechnology for soil stabilization can make subgrade soils well bonded, strong and flexible, allowing the designer to assume higher values of Resilient Moduli in the AASHTO 1993 design equation, which may bring the required structural number down and allow a lighter design of cross-section of structural layers on top of the subgrade. Indicative calculations for a typical 100 MSA, two lane (10 m wide) highway show that the new technology, while remaining within the AASHTO 1993 design guidelines, enables designing a pavement that is 3 times better (it will now be a 300 MSA pavement instead of 100 MSA) with a cost reduction of about USD 114000 per km. This paper takes an overview of latest trends in USA regarding pavement design approaches. It also puts forth, the opportunities presented to a pavement designer, by the new nanotechnology and proposes a new design approach, for optimized pavement design - green, sustainable & economical; while remaining within the AASHTO 1993 guidelines or MEPDG.

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.

PURPOSES : This paper focuses on strength development according to the mix design with cement type and mineral admixture from laboratory and field tests in cool weather. METHODS : Two methods evaluated the mix design of concrete pavement in cool weather. Firstly, laboratory tests including slump, air contents, setting time, strength, maturity, and freezing-thawing test were conducted. Three alternatives were selected based on the tests. Secondly, a field test was conducted and the optimum mix design in cool weather was suggested . RESULTS : It is an evident from the laboratory test that a mix with type Ⅲ cement showed better performance than the one with type Ⅰ cement. There was a delay in strength development of a mix with mineral admixture compared to mix design without any mineral admixture. In the field test, type Ⅲ cement+flyash 20% mix design proved the best performance. CONCLUSIONS : For concrete pavement in cool weather, mix design using type Ⅲ cement could overcome the strength delay due to mineral admixture. Moreover, it is possible to make sure of durability of pavement. Therefore, strength and durability problems due to cool weather would decrease.