PURPOSES : In this study, we evaluated the quality levels of abrasion resistance and freeze-thaw resistance to the surface layer (colored layer) by using an overseas abrasion resistance test method to confirm the quality suitability of the concrete block surface for a domestic production permeable block. METHODS : In this study, a new evaluation item for increased durability apart from the quality standard of the permeable block was considered, namely, evaluation of the durability of the surface layer and the freeze-thaw resistance of the permeable block itself by EN 1338, ASTM C 779, 994, and GR 4009 (KS F 4419). RESULTS : The abrasion resistance test for the permeable block revealed that there were relative differences according to the different test methods. However, it was observed that if the ASTM C 779 test results did not meet the wear resistance quality standards, it did not satisfy ASTM C 944 and EN 1338. The ASTM C 779 test result was analyzed to have the highest objectivity and discernment, and this test method was proposed as a permeable block wear test method. In addition, the freeze-thaw resistance test method by the GR 4007 standard can be measured by strength, so it is possible to evaluate the resistance of the permeable block through this test method. CONCLUSIONS : The abrasion resistance test and freeze-thaw resistance test can contribute to the improvement of the permeable block when added to the current quality evaluation tests.

PURPOSES : This study was conducted to analyze the problems of the permeable block by objectively evaluating the quality of the permeable block and providing basic data to improve the quality and construction defect of the permeable block pavement in accordance with the continuously increasing demand of the permeable block. METHODS : In this study, we evaluated the current quality standard suitability of nine products to evaluate the current quality level of domestic production permeable blocks. The evaluation items were evaluated for surface layer thickness, block dimension, strength, and permeability coefficient, and the Korea Standard suitability for these evaluation items was analyzed. In addition, a three-dimensional finite element analysis was conducted to determine the effect of vehicle load on the deformation of block pavement structure. RESULTS : The results demonstrated that the surface layer (colored layer) thicknesses of domestically produced permeable block products were different according to the quality standards, and the dimensions were evaluated to be excellent for domestic permeable blocks currently being produced and delivered. In addition, the strength and permeability coefficient evaluation result demonstrated that all products meet the strength and permeability coefficient quality standards, but the correlation between these strengths and permeability coefficients is not high. The quality standard of strength and permeability coefficients is evaluated as being sufficiently achieved by domestic production technology. CONCLUSIONS: The intensity and permeability coefficients measured in this study were in line with the quality standards; however, the variable coefficient was found to have a significant difference in the quality control level from a maximum of 26% to a minimum 1.7%.

PURPOSES : In this study, a numerical clogging model that can be used to realistically visualize the movement of particles in cylindrical permeability test equipment was proposed based on the system coupling of computational fluid dynamics with the discrete element method and experimental permeability test results. This model can also be used to simulate the interaction of dust particles with bedding particles. METHODS: A 4-way system coupling method with multiphase volumes of the fluid model and porous media model was proposed. The proposed model needs to consider the influence of flow on the dust particles, interaction between the dust particles, and interaction between the dust particles and bedding layer particles. The permeability coefficient of the bedding layer in cylindrical permeability test equipment was not calculated by using the permeability test result, but was estimated by using the particle packing model and Ergun model. RESULTS : The numerical simulation demonstrated a good agreement with the experimental test results in terms of permeability and drain time. Additionally, the initial movement of particles due to the sudden drain hole opening was successfully captured by the numerical model. CONCLUSIONS : A 4-way coupling model was sufficient to simulate the water flow and particle movement in cylindrical permeability test equipment. However, additional tests and simulation are required to utilize the model for more realistic block pavement systems.

PURPOSES : In this study, a series of fundamental falling head permeability tests were conducted on a binary particle mix bedding to determine the minimum water level, bedding layer thickness, and amount of dust that can result in the stable permeability with high repeatability. The determined condition is used to develop a CFD-DEM coupled clogging model that can explain the movement of dust particles in flowing water of a block pavement system. METHODS: A binary particle mixture is utilized to experimentally simulate an ideal bedding layer of a block pavement system. To obtain a bedding layer with maximum packing degree, the well-known particle packing degree model, i.e., the modified Toufar model, was utilized. The permeability of the bedding layer for various water levels, bedding layer thicknesses, and amounts of dust was calculated. The permeability for a small water level drop was also plotted to evaluate the effect of dust on the bedding layer clogging. RESULTS: It was observed that a water level of 100 mm, bedding depth of 70 mm, and dust amount of 0.3 g result in a stable permeability condition with high repeatability. The relationship between the minimum dust amount and surface clogging of the bedding layer was suggested based on the evaluation of the volumetric calculation of the particle and void and the permeability change in the test. CONCLUSIONS: The test procedure to determine the minimum water level, bedding thickness, and dust amount was successfully proposed. The mechanism of clogging on the surface of the bedding layer was examined by relating the volumetric characteristics of dust to the clogging surface.

PURPOSES: The permeable pavement type has been rapidly developed for solving problems regarding traffic noise in the area of housing complex and heavy rainwater drainage in order to account for the climate change. In this regards, the objective of this study is to figure out the characteristics of pavement types. METHODS: The laboratory test for deriving optimum asphalt content (OAC) was conducted using the mixtures of the permeable asphalt surface for the pavement surface from Marshall compaction method. Based on its results, the pavement construction at the test field was conducted. After that, the site performance tests for measuring the traffic noise, strength and permeability were carried out for the relative evaluation in 2 months after the traffic opening. The specific site tests are noble close proximity method (NCPX), Light falling deflectometer test (LFWD) and the compact permeability test. RESULTS : The ordered highest values of the traffic noise level can be found such as normal dense graded asphalt, drainage and porous structure types. In the results from LFWD, the strength values of the porous and drainage asphalt types had been lower, but the strength of normal asphalt structure had relatively stayed high. CONCLUSIONS: The porous structure has been shown to perform significantly better in permeability and noise reduction than others. In addition to this study, the evaluation of the properties and the determination of the optimum thickness for the subgrade course under the porous pavement will be conducted using ground investigation technique in the further research.

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.

최근 아스팔트 포장의 개･보수 및 각종 관로 교체공사 시 발생하는 폐아스콘 발생량이 매년 증가하고 있다. 이러한 폐아스콘을 100% 순환골재로 재활용함은 물론 아스팔트 가열시 CO2 발생현상과 지하수자 원 고갈 등의 경제적․환경적 문제점을 해결하기 위한 투수성 포장재료의 제조를 통해 탄소배출량 저감, 지 하수자원 보존 및 집중호우로 인한 도심지 침수 방지에 효과적일 것으로 예상된다. 따라서, 본 연구에서는 상온에서 순환골재를 재활용하기 위해여 사전 실험으로 도출된 최적의 MMA 수 지 결합재와 폐아스콘 순환골재를 전량 활용한 투수성 상온 재생아스팔트 혼합물의 물리･역학적 성능, 내 구성능 분석 및 현장 시험시공을 통한 적용성을 평가하였다. MMA계 수지 결합재와 폐아스콘 순환골재를 활용한 배합의 최적조건에서 마샬안정도는 14,280N, 흐름 값은 23.5(1/10mm)로 나타나 KS F 2385『투수성 아스팔트 혼합물』의 품질규정의 목표치를 만족하였다. 공극률 및 투수계수는 각각 평균 20.44%, 0.94 cm/sec로 측정되었다. 폐아스콘 순환골재의 입도분포 특 성에 따라 각 공시체 별로 차이를 있으나 현재 국내의 투수성 아스팔트 혼합물의 기준치를 모두 안정적으 로 만족하였다. 또한 25℃ 상온에서 변형률과 동적안정도가 평균 각각 1.21mm/min 및 4,070회/mm로 나타났으며, 공시체의 파괴는 작으며 투수성 포장재료로 가능할 것으로 판단된다. 폐아스콘 순환골재와 MMA계 수지를 이용한 투수성 상온 재생아스팔트 시험시공 후 재령별 코어채취 및 안정도를 측정한 결과, 상온 아스팔트의 품질시험 재령인 10일의 경우에는 공시체가 완벽히 하부까지 채취할 수 있었으며 채취한 공시체의 마샬안정도 및 흐름값이 12,420N과 25.6(1/10mm)로 투수성 아스팔 트 조성물의 KS 기준을 모두 만족하는 것으로 나타났다. 시험시공 이후 3개월간 포장면을 모니터링 한 결과, 포장체의 균열 및 파손은 관찰되지 않았으며, 골재의 박리가 일어나는 현상 또한 보이지 않아 기존 의 기술로 포장된 면의 성능과 유사한 것으로 현장 성능이 우수한 것으로 판단된다. 한편, 시험시공 포장 체의 현장 투수성능을 시험한 결과 포장체의 투수량이 1,622(mL/15s) 이상으로 매우 우수한 것으로 사료 되며 투수성 포장체로서 성능이 충분한 것으로 판단된다.

A rapid urbanization has increased the portion of paved layer that results in the change of water circulation system. This change leads to frequent events of flooding, drought, and urban heat island. To resolve these issues, permeable pavement system based on Low Impact Development (LID) concept is being applied to international urban areas. Therefore it is necessary to establish a rational design procedure for the permeable pavement system that reflects our environmental conditions. iDue to inherent characteristics of permeable pavement system, water infiltrates thorough the layers so it may reduce the bearing capacity of sub-layers. In this study, an effort was made to investigate the effectiveness of geogrid reinforced crushed stone subbase layer based on field experimental program along with a limited numerical analysis. It reveals that geogrid reinforced sections improve the bearing capacity by close to 20%. In addition, a light weight deflectomenter (LWDT) appears to be promising for the compaction quality control of crushed stone subbase layer in order to construct qualified permeable pavement systems.

최근 급격한 도시화 및 산업화로 인한 불투수층의 증가로 물순환 체계가 파괴되고 그 결과 홍수피해해, 지하수고갈, 하천의 건천화 등의 문제가 발생하고 있다. 이 문제를 해결 하고자 저영향개발(low impact development, LID)개념을 도입한 투수성 포장체 및 설계에 대한 연구가 진행되고 있다. 투수성 포장 특 성상 우수의 유입이 예상되며 이에 따르는 포장체 하부층의 지지력 감소에 의한 구조적 건전성에 영향을 미치게 된다. 따라서 본 연구에서는 하부 보조기층의 지오그리드 보강 유무에 따른 구조적 안정성을 검토 현장 실험을 통해서 검증해 보고자 한다. 지오그리드 보강위치, 지오그리드 종류, 지오그리드 유무 에 대 한 각각 다른 시험 포장체 4개소를 시공하여 실험을 진행하였다. 보조기층은 일반 혼합골재 대신 투수성이 높은 쇄석을 사용하였고, 평판재하시험 ․ 동평판재하시험을 통 하여 쇄석보조기층 지오그리드 보강 효과를 검증하고자 한다.

PURPOSES: This study aims to evaluate the runoff reduction with permeable pavements using the SWMM analysis. METHODS: In this study, simulations were carried out using two different models, simple and complex, to evaluate the runoff reduction when an impermeable pavement is replaced with a permeable pavement. In the simple model, the target area for the analysis was grouped into four areas by the land use characteristics, using the statistical database. In the complex model, simulation was performed based on the data on the sewer and road network configuration of Yongsan-Gu Bogwang-Dong in Seoul, using the ArcGIS software. A scenario was created to investigate the hydro-performance of the permeable pavement based on the return period, runoff coefficient, and the area of permeable pavement that could be laid within one hour after rainfall. RESULTS : The simple modeling analysis results showed that, when an impervious pavement is replaced with a permeable pavement, the peak discharge reduced from 16.7 m3/s to 10.4 m3/s. This represents a reduction of approximately 37.6%. The peak discharge from the whole basin showed a reduction of approximately 11.0%, and the quantity decreased from 52.9 m3/s to 47.2 m3/s. The total flowoff reduced from 43,261 m3 to 38,551 m3, i.e., by approximately 10.9%. In the complex model, performed using the ArcGIS interpretation with fewer permeable pavements applicable, the return period and the runoff coefficient increased, and the total flowoff and peak discharge also increased. When the return period was set to 20 years, and a runoff coefficient of 0.05 was applied to all the roads, the total outflow reduced by 5195.7 m3, and the ratio reduced to 11.7%. When the return period was increased from 20 years to 30 and 100 years, the total outflow reduction decreased from 11.7% to 8.0% and 5.1%, respectively. When a runoff coefficient of 0.5 was applied to all the roads under the return period of 20 years, the total outflow reduction was 10.8%; when the return period was increased to 30 and 100 years, the total outflow reduction decreased to 6.5% and 2.9%, respectively. However, unlike in the simple model, for all the cases in the complex model, the peak discharge reductions were less than 1%. CONCLUSIONS : Being one of the techniques for water circulation and runoff reduction, a high reduction for the small return period rainfall event of penetration was obtained by applying permeable pavements instead of impermeable pavement. With the SWMM analysis results, it was proved that changing to permeable pavement is one of the ways to effectively provide water circulation to various green infrastructure projects, and for stormwater management in urban watersheds.

국내 투수 콘크리트 포장을 시공할 시 발생하는 주요 문제점으로는 포장의 다짐도 만족과 다짐형식 및 방법에 의해 표면 공극 막힘 현상이 발생하는 현상을 꼽을 수 있다. 본 연구는 이에 투수성 콘크리트 포장 을 다짐할 시 다짐 에너지의 영향과 다짐 롤러 타입이 공극막힘에 미치는 영향을 실험적으로 규명하고 그 에 따른 개선책을 제시하는 것에 목적을 두었다. 본 연구를 수행하기 위해 두 가지 실험을 진행하였다. 첫 번째, 하중 유도 진동 실험을 실시하여 동일한 크기의 하중을 재하하는 조건 하에 서로 다른 진동시간을 설정하여 다짐 에너지의 영향을 확인하였다. 두 번째, 실제 포장 슬래브를 모사하여 형식이 다른 다짐롤 러를 적용하여 표면 공극 막힘이나 압축강도, 마모저항성 그리고 투수계수를 측정하여 다짐에 의한 성능 변화를 비교하였다. 실험 결과는 다음과 같다. 다짐 에너지가 증가할수록, 단위중량과 압축강도는 증가하나, 공극률과 투수 계수는 감소하는 경향이 나타났다. 물 분사를 실시하면서 철제 표면을 가진 다짐롤러로 다짐을 진행하였 을 시에는 물/시멘트 비의 변화로 인하여 시멘트 페이스트가 발생하여 표면 공극 막힘 현상이 발생하였 다. 그러나 반면 롤러 표면을 오일로 코팅하였거나 고무 롤러를 적용하여 다짐을 실시한 경우, 슬래브 표 면 공극 막힘률이 기존 방법을 사용하였을 시보다 상당히 개선되었으며 시편의 압축강도와 마모저항성 및 투수 성능에 있어서도 더욱 높은 결과치를 나타내었다.

PURPOSES : The objective of this study is to evaluate the effectiveness of a geogrid reinforced subbase of permeable flexible pavement structures with respect to permanent deformation. METHODS : Experimental trials employing a repeated triaxial load test scheme were conducted for both a geogrid reinforced subbase material and a control specimen to obtain the permanent deformation properties based on the VESYS model. Along with this, a finite elementbased numerical analysis was conducted to predict pavement performance with respect to the rutting model incorporated into the analysis. RESULTS AND CONCLUSIONS: The results of the experimental study reveal that the geogrid reinforcement seems to be effective in mitigating permanent deformation of the subbase material. The permanent deformation was mostly achieved in the early stages of loading and then rapidly reached equilibrium as the number of load applications increased. The ultimate permanent deformation due to the geogrid reinforcement was about 1.5 times less than that of the control specimen. Numerical analysis showed that the permeable, flexible pavement structure with the geogrid reinforced subbase also exhibits less development of rutting throughout the service life. This reduction in rutting led to a 20% decrease in thickness of the subbase layer, which might be beneficial to reduce construction costs unless the structural adequacy is not ensured. In the near future, further verification must be conducted, both experimentally and numerically, to support these findings.

최근 전 세계적인 이상기온 현상으로 인하여 기후변화에 따른 극심한 강우 및 강설빈도가 많아지고 동 절기 기록적인 한파로 인하여 콘크리트의 내구성 특히 동결융해 저항성에 대한 검토가 필연적인 항목이 되었다. 강우 및 강설 상황 시, 공항포장의 표면에 우수 또는 우설에 의한 침투수 및 동결융해 현상에 의 해 포장체의 구조적 성능이 저하될 우려가 있으며 이에 따른 조기파손의 영향으로 항공기의 이·착륙 시 안전에 저해요소로 작용할 소지가 있으므로 이에 대한 대책이 필요한 실정이다. 따라서 본 연구에서는 투수콘크리트를 공항포장용 배수성 시멘트안정처리기층에 적용하기 위한 연구의 일환으로 동결융해 저항성을 분석하고자 한다. 또한 시멘트안정처리기층에 적용하기 위한 투수콘크리트에 대한 동결융해 저항성 기준이 존재하지 않아 미연방항공청(Federal Aviation Administration, FAA) 기준에 명시되어 있는 ASTM D 560 Standard Test Methods for Freezing and Thawing Compacted Soil-Cement Mixtures에 의거하여 중량손실율을 측정하였다. 본 연구에서 고려한 각 실험변수는 고로 슬래그 미분말을 치환하지 않은 Plain 변수를 포함하여 고로슬래그 미분말을 10%, 30% 및 50% 치환한 총 4가지 변수에 대하여 실험을 진행하였다. 동결융해에 의한 중량손실율 실험결과, 중량손실율 측정은 13Cycle까지 실험을 수행하였으며 Plain 변수를 포함하여 고로슬래그 미분말을 10%, 30% 및 50% 치환한 모든 변수에서 동결웅해에 의한 중량손실율이 1% 미만으로 분석되었다. FAA AC 150-5370-10a에 명시되어 있는 ASTM D 560을 활용하여 동결 융해 12Cycle에서의 중량손실율 14% 이하의 값을 월등히 만족하는 것으로 나타났다. 따라서 공항포장용 배수성 시멘트안정처리기층에 적용하기 위한 투수콘크리트의 동결융해 저항성 확보가 충분히 가능할 것 으로 판단된다.

PURPOSES : As a research to develop a cement treated base course for an airport pavement which can enhance its drainage, this paper investigated the strength, infiltration performance and durability of the pervious concrete with respect to maximum coarse aggregate sizes and compaction methods. METHODS : This study measured compressive strength, infiltration rate, continuous porosity and freeze-thaw resistance of pervious concrete specimens, which were fabricated with five different compaction methods and different maximum aggregate sizes. In addition, in order to reduce the usage of Portland cement content and to enhance environment-friendliness, a portion of the cement was replaced with Ground Granulated Blast Furnace Slag (GGBS). RESULTS: Compressive strength requirement, 5 MPa at 7 days, was met for all applied compaction methods and aggregate sizes, except for the case of self-compaction. Infiltration rate became increased as the size of aggregate increased. The measured continuous porosities varied with the different compaction methods but the variation was not significant. When GGBS was incorporated, the strength requirement was successfully satisfied and the resistance to freezing-thawing was also superior to the required limit. CONCLUSIONS: The infiltration rate increased as the maximum size of aggregate increased but considering construct ability and supply of course aggregate, its size is recommended to be 25mm. With the suggested mix proportions, the developed pervious concrete is expected to successfully meet requirements for strength, drainage and durability for cement treated base or subbase course of an airport pavement.