• 한국도로학회논문집
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• 제3권1호
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• pp.165-176
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• 2001

줄눈콘크리트포장의 줄눈은 온도 및 습도변화에 기인하여 발생하는 슬래브내에 무작위하게 발생하는 균열을 제어할 목적으로 설계된다. 이러한 인위적인 균열 (줄눈)은 자연발생적인 균열에 비하여 줄눈채움, 하중전달장치등의 보호대책을 강구하는 것이 용이하다는 장점을 가지고 있다. 줄눈채움의 잠재적인 이점은 표면수의 하부층으로의 침투로 인한 하부층의 약화 및 비압축성 물질 (작은 입자위 골재)의 줄눈내에 끼어듦으로 인한 스폴링을 방지하는데 있다. 합리적인 줄눈 채움의 설계를 위해서는 줄눈폭의 변화 (줄눈의 수평 움직임)의 산정이 중요한 입력요소이다. LTPP SMP 연구에 포함된 16개의 줄눈콘크리트포장의 줄눈의 수평움직임에 대한 장기 현장계측자료를 토대로 상당수의 줄눈에서 수평움직임을 허용하지 않고 있다는 것이 밝혀진바 있다. 이러한 현상을 줄눈잠김이라고 한다. 줄눈잠김이 발생하는 원인은 설계상에 계획된 줄눈부의 균열이 발생하지 않기 때문이라고 추정된다. 본 연구에서는 임의의 줄눈콘크리트포장에서 줄눈잠김의 비율을 예측할 수 있는 모델을 제시하였고 줄눈 잠김이 포장체의 성능에 미치는 영향을 조사하였다.

• 한국도로학회논문집
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• 제16권5호
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• pp.73-82
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• 2014

PURPOSES : The purpose of this study is to determine the optimum addition rate of SBR latex through the evaluation of durability and strength of SBR latex applied soil pavement. Formerly used materials such as fly ash and cement in soil pavement had resulted in decreased durability due to micro crack by heat of hydration and shrinkage crack in winter. However, that agglutinated polymers help adhesion to aggregate increased comes up with preventing the crack opening when the number of capillary tubes of SBR latex get decreased in the hydration process of cement. Therefore, in this study, it is suggested that the evaluation of the field applicability of soil pavement be conducted through the performance lab test in terms of strength increment, adhesion improvement, and crack resistance based on SBR latex addition rate. METHODS : In order to evaluate the field applicability of soil pavement, SBR latex was added 0 to 3% by 1% increment, with fixed cement contents of 3% and 5%. The resistance of shear failure and crack of soil pavement were evaluated by performing the uniaxial compressive strength test and indirect tensile strength test at -20 and $20^{\circ}C$, respectively. RESULTSCONCLUSIONS : It was found out that from both tests, resistance of shear failure and crack were improved with increment of curing time, and especially more than 2% of SBR latex addition rate and 5% cement content gave better results.

• 한국도로학회논문집
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• 제13권1호
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• pp.79-86
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• 2011

최근 화석자원의 고갈과 대기오염의 피해를 저감하기 위해 자전거의 이용을 적극적으로 장려하고 있으며 이를 위해 자전거도로 건설이 활발히 이루어지고 있다. 하지만 현재 사용 중인 자전거도로 포장은 이용 하중에 비해 높은 성능과 시공비용을 지니고 있어 효율적인 건설을 위해 경제적인 도로포장형식이 필요하다. 롤러 전압 콘크리트 포장은 시멘트 경화 반응과 다짐으로 인한 골재 맞물림에 따른 높은 구조적 성능을 확보할 수 있다. 또한 시공이 간단하고 건설비가 적어서 자전거도로에 적용하기 위한 우수한 조건을 갖추고 있다. 그러나 롤러 전압 콘크리트 포장의 불량한 표면 미관과 제설제 피해에 대한 취약성은 자전거도로 건설에서 문제로 작용하고 있다. 따라서 이러한 단점을 극복하기 위해 표면 미관의 개선과 환경하중에 대한 피해를 저감 할 수 있을 것으로 예상되는 코팅공법을 이용하였으며 이에 대한 효과를 검증하기 위해 롤러 전압 콘크리트 포장의 코팅에 따른 성능을 검토하였다.

• 한국도로학회논문집
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• 제7권4호
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• pp.69-77
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• 2005

줄눈 콘크리트포장에서 적정한 줄눈간격은 슬래브의 거동에 의해 발생하는 인장응력 줄눈채움재의 파손과 다웰바의 하중전달율(LTE)의 저하를 방지하여 도로포장의 장기 공용성 증가에 큰 영향을 미친다. 하지만 국내 줄눈간격은 경험적이고 획일적으로 이루어진다. 그러므로 본 연구는 국내 권역별 기후조건을 토대로 합리적인 줄눈간격 산정에 대한 방안을 제시하였다. 합리적인 줄눈간격은 초기거동에서 환경하중의 영향에 따른 건조수축과 수화열에 의해 무작위 균열 발생하지 않도록 산정하였다. 그리고 장기거동에서 줄눈폭의 과도한 움직임에 따른 LTE 저하로 인해 포장파손이 발생하지 않도록 줄눈간격을 산정하였다. 본 연구에서 산정된 줄눈간격 잠정안은 6$\sim$8m이며, 포장파손 예측 모델을 통해 줄눈간격을 8m로 증가시켜도 포장 공용성엔 큰 차이가 없었다.

• 한국도로학회논문집
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• 제16권6호
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• pp.69-78
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• 2014

PURPOSES : The purpose of this paper is showing that the state of pavement sublayers can be evaluated differently according to direction of FWD. METHODS : The concrete pavement slabs above subgrade without anything, subgrade with cavity, and box culvert were modeled by finite element method(FEM). The modeled pavements were analyzed by changing the direction of falling weight deflectometer(FWD). The deflection results obtained from FEM were used to calculate radius of relative stiffness and composite modulus of subgrade reaction using AREA method. Then, the analyzed results were compared to the results of the test performed at the Korea Expressway Corporation(KEC) test road. RESULTS : The composite modulus of subgrade reaction increased with subgrade elastic modulus, while radius of relative stiffness decreased. The pavement sections of pure earth showed the consistent results regardless of FWD direction. In case there was cavity, the radius of relative stiffness was larger and composite modulus of subgrade reaction was smaller when FWD was leaving the cavity than when approaching the cavity. This pattern became clear when the cavity got larger. In case of the section with box culvert, the pattern was opposite to the case of cavity. When the soil cover depth increased, the effect of box culvert got smaller. When the load was applied far from the cavity and box culvert, the effect was also declined. The test performed at the KEC test road showed identical results to those of finite element analysis. CONCLUSIONS : The direction of FWD should be considered in evaluation of the state of pavement sublayers because it can be evaluated differently even under identical condition.

• 한국도로학회논문집
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• 제16권4호
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• pp.1-9
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• 2014

PURPOSES: The objective of this study is to evaluate construction issues and design for transverse steel in continuously reinforced concrete pavement(CRCP). METHODS : The first continuously reinforced concrete pavement(CRCP) design procedure appeared in the 1972 edition of the "AASHTO Interim Guide for Design of Pavement Structures", which was published in 1981 with Chapter 3 "Guide for the Design of Rigid Pavement" revised. A theory that was accepted at that time for the analysis of steel stress in concrete pavement, called subgrade drag theory(SGDT), was utilized for the design of reinforcement of CRCP - tie bar design and transverse steel design - in the aforementioned AASHTO Interim Guide. However SGDT has severe limitations due to simple assumptions made in the development of the theory. As a result, any design procedures for reinforcement utilizing SGDT may have intrinsic flaws and limitations. In this paper, CRCP design procedure for transverse steel was introduced and the limitations of assumptions for SGDT were evaluated based on various field testing. RESULTS: Various field tests were conducted to evaluate whether the assumptions of SGDT are reasonable or not. Test results show that 1) temperature variations exist along the concrete slab depth, 2) very little stress in transverse steel, and 3) warping and curling in concrete slab from the field test results. As a result, it is clearly revealed out that the assumptions of SGDT are not valid, and transverse steel and tie bar designs should be based on more reasonable theories. CONCLUSIONS : Since longitudinal joint is provided at 4.1-m spacing in Korea, as long as joint saw-cut is made in accordance with specification requirements, the probability of full-depth longitudinal cracking is extremely small. Hence, for transverse steel, the design should be based on the premise that its function is to keep the longitudinal steel at the correct locations. If longitudinal steel can be placed at the correct locations within tolerance limits, transverse steel is no longer needed.

• 한국도로학회논문집
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• 제19권1호
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• pp.37-44
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• 2017

PURPOSES : This study is primarily focused on evaluating the effects of the non-linear stress-strain behavior of RAP concrete on structural response characteristics as is applicable to concrete pavement. METHODS : A 3D FE model was developed by incorporating the actual stress-strain behavior of RAP concrete obtained via flexural strength testing as a material property model to evaluate the effects of the non-linear stress-strain behavior to failure on the maximum stresses in the concrete slab and potential performance prediction results. In addition, a typical linear elastic model was employed to analyze the structural responses for comparison purposes. The analytical results from the FE model incorporating the actual stress-strain behavior of RAP concrete were compared to the corresponding results from the linear elastic FE model. RESULTS : The results indicate that the linear elastic model tends to yield higher predicted maximum stresses in the concrete as compared to those obtained via the actual stress-strain model. Consequently, these higher predicted stresses lead to a difference in potential performance of the concrete pavement containing RAP. CONCLUSIONS : Analysis of the concrete pavement containing RAP demonstrated that an appropriate analytical model using the actual stress-strain characteristics should be employed to calculate the structural responses of RAP concrete pavement instead of simply assuming the concrete to be a linear elastic material.

• 한국도로학회논문집
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• 제5권3호
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• pp.21-29
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• 2003

현재 공항포장은 기존 포장관련정보의 관리에 대한 어려움이 있고, 장기공용으로 인해 유지보수비용이 증가하고 있어 예산의 효율적 활용과 공항포장의 체계적 유지관리가 필요하다. 이를 위해서 포장관리시스템을 도입할 필요성이 있다. 본 연구에서는 외국의 여러 포장관리시스템 중 세계적으로 널리 활용되고 있는 Micro PAVER를 국내에 도입하기 위한 방안을 연구하였다. 외국의 시스템을 국내에 적용하기 위해서는 환경차이, 포장관리수준 차이 등으로 인해 발생하는 오류를 최소화하기 위해 국내에 맞도록 적정화(customization)하는 연구가 필요하다. 따라서 본 연구에서는 Micro PAVER를 국내에 도입하기 위해 필요한 적정화 연구를 수행하였다 Micro PAVER의 논리 및 구조를 분석하여 Micro PAVER 운영에 주요하게 작용하는 부분을 기존 포장평가자료와 포장 전문가의 설문조사 방법을 이용하여 적정화하였다. 주요 적정화 부분은 포장파손예측모형, critical PCI, PCI에 따른 유지보수비용, 유지보수공법 및 단가, PCI 등급이다.

• 한국도로학회논문집
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• 제18권1호
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• pp.33-41
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• 2016

PURPOSES : This study primarily focused on evaluating the performance characteristics of 4.75-mm nominal maximum aggregate size (NMAS) asphalt mixtures for their more effective implementation to a layered flexible pavement system. METHODS : The full-scale pavements in the FDOT's accelerated pavement testing (APT) program, including 4.75-mm mixtures at the top with different thicknesses and asphalt binder types, were considered for the faster and more realistic evaluation of the rutting performance. The results of superpave indirect tensile (IDT) tests and hot-mix asphalt fracture mechanics (HMA-FM) based model predictions were used for cracking performance assessments. RESULTS : The results indicated that the rutting performance of pavement structures with 4.75-mm mixtures may not be as good as to those with the typical 12.5-mm mixtures, and pavement rutting was primarily confined to the top layer of 4.75-mm mixtures. This was likely due to the relatively higher mixture instability and lower shear resistance compared to 12.5-mm mixtures. The energy ratio (ER) and HMA-FM based model performance prediction results showed a potential benefit of 4.75-mm mixtures in enhanced cracking resistance. CONCLUSIONS : In relation to their implementation, the best use of 4.75-mm mixtures seem to be as a surface course for low-traffic-volume applications. These mixtures can also be properly used as a preservation treatment that does not necessarily last as long as 12.5-mm NMAS structural mixes. It is recommended that adequate thicknesses and binder types be considered for the proper application of a 4.75-mm mixture in asphalt pavements to effectively resist both rutting and cracking.

• 한국도로학회논문집
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• 제18권2호
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• pp.83-90
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• 2016

PURPOSES : Nowadays, cavity phenomena occur increasingly in pavement layers of downtown areas. This leads to an increment in the number of potholes, sinkholes, and other failure on the road. A loss of earth and sand from the pavement plays a key role in the occurrence of cavities, and, hence, a structural-performance evaluation of the pavement is essential. METHODS: The structural performance was evaluated via finite-element analysis using KPRP and KICTPAVE. KPRP was developed in order to formulate a Korean pavement design guide, which is based on a mechanical-empirical pavement design guide (M-EPDG). RESULTS: Installation of the anti-freezing layer yielded a fatigue crack, permanent deformation, and international roughness index (IRI) of 13%, 0.7 cm, and 3.0 m/km, respectively, as determined from the performance analysis conducted via KPRP. These values satisfy the design standards (fatigue crack: 20%, permanent deformation: 1.3 cm, IRI: 3.5 m/km). The results of FEM, using KICTPAVE, are shown in Figures 8~12 and Tables 3~5. CONCLUSIONS: The results of the performance analysis (conducted via KPRP) satisfy the design standards, even if the thickness of the anti-freezing layer is not considered. The corresponding values (i.e., 13%, 0.7 cm, and 3.0 m/km) are obtained for all conditions under which this layer is applied. Furthermore, the stress and strain on the interlayer between the sub-grade and the anti-freezing layer decrease gradually with increasing thickness of the anti-freezing layer. In contrast, the strain on the interlayer between the sub-base and the anti-freezing layer increases gradually with this increase in thickness.