• 한국도로학회논문집
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• 제9권2호
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• pp.89-99
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• 2007

복소수계수 $E^*$로 표현되는 아스팔트 콘크리트의 탄성계수는 아스팔트 포장설계에서 매우 중요한 입력변수다. 일반적으로 아스팔트 콘크리트의 탄성계수는 동탄성 계수시험 (Dynamic Modulus Test)을 사용하여 평가한다. 그러나 동탄성계수시험은 일상적인 시험법으로 적용하기에는 고가의 시험장비, 복잡한 시험장비, 많은 시험시간 등의 문제가 있다. 이에 반하여 충격공진시험(IR: Impact Resonance test)은 비파괴시험으로서 간편한 시험장치, 단순한 시험방법이며 반복성이 뛰어나다. 본 연구의 주요 목적은 충격하중의 타격위치 시편거치 방법 충격하중원의 특성, 신호획득 속도, 신호처리방법 등을 포함한 IR시험의 시험조건의 영향을 평가하는 것이다. 본 연구에서 적용한 모든 시험조건 범위에서 충격공진시험에서 측정된 결과의 변동은 ${\pm}2.7%$ 이내에 들었다.

• 한국도로학회논문집
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• 제17권3호
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• pp.77-83
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• 2015

PURPOSES : In this study, a fracture-based finite element (FE) model is proposed to evaluate the fracture behavior of fiber-reinforced asphalt (FRA) concrete under various interface conditions. METHODS : A fracture-based FE model was developed to simulate a double-edge notched tension (DENT) test. A cohesive zone model (CZM) and linear viscoelastic model were implemented to model the fracture behavior and viscous behavior of the FRA concrete, respectively. Three models were developed to characterize the behavior of interfacial bonding between the fiber reinforcement and surrounding materials. In the first model, the fracture property of the asphalt concrete was modified to study the effect of fiber reinforcement. In the second model, spring elements were used to simulated the fiber reinforcement. In the third method, bar and spring elements, based on a nonlinear bond-slip model, were used to simulate the fiber reinforcement and interfacial bonding conditions. The performance of the FRA in resisting crack development under various interfacial conditions was evaluated. RESULTS : The elastic modulus of the fibers was not sensitive to the behavior of the FRA in the DENT test before crack initiation. After crack development, the fracture resistance of the FRA was found to have enhanced considerably as the elastic modulus of the fibers increased from 450 MPa to 900 MPa. When the adhesion between the fibers and asphalt concrete was sufficiently high, the fiber reinforcement was effective. It means that the interfacial bonding conditions affect the fracture resistance of the FRA significantly. CONCLUSIONS : The bar/spring element models were more effective in representing the local behavior of the fibers and interfacial bonding than the fracture energy approach. The reinforcement effect is more significant after crack initiation, as the fibers can be pulled out sufficiently. Both the elastic modulus of the fiber reinforcement and the interfacial bonding were significant in controlling crack development in the FRA.

• 한국도로학회논문집
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• 제17권1호
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• pp.17-24
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• 2015

PURPOSES : Recently, crack, rutting, and stripping problems from the surface of asphalt pavements in National highway are observed and they affect the drivers to feel uncomfortable on the road. Surface treatments are recommended to use in distressed pavements due to cost-effective, and improvement of surface performance. The purpose of this study is to evaluate the performance of micro-surfacing and polymer slurry seal treatments for distressed asphalt pavements. METHODS : Surface conditions and friction resistance are evaluated for asphalt pavements treated with micro-surfacing and polymer slurry seal mixes in National highway 30 line and 34 line. Visual observation is conducted and surface performance is measured by PES (Performance Evaluation Surveyor) in terms of crack ratio, rutting and IRI(International Roughness Index). BPN(British Pendulum Number) is measured by BPT(British Pendulum Tester) to evaluate the friction resistance in the field. RESULTS : The surface evaluation results are presented for asphalt pavement treated with micro-surfacing and polymer slurry seal treatments in National highway 30 line and 34 line. Based on the visual observation, micro-surfacing and polymer slurry seal treatments show better improvements in terms of cracks and stripping. Based on the surface conditions measured by PES vehicle, the surface performance of micro-surfacing treatments improves from 53.3% to 54.2% and the surface performance of polymer slurry seal treatments improves from 21.6% to 59.7%. However, the friction resistance of both micro-surfacing and polymer slurry seal treatments decreases from 2.5% to 6.7%. Further, it should be verified to produce the surface exposed with aggregates during the construction process of both treatment methods in the field. CONCLUSIONS : Based on the performance evaluation results in the filed, the surface performance of asphalt pavement treated with micro-surfacing and polymer slurry seal treatments improves from 21.6% to 59.7%. While, the friction resistance of asphalt pavement treated with micro-surfacing and polymer slurry seal treatments does not improve. It can be concluded that current micro-surfacing and polymer slurry seal treatments would improve surface performance but would not improve the friction resistance.

• Computers and Concrete
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• 제14권5호
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• pp.527-546
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• 2014

Portland cement concrete, which has higher strength and stiffness than asphalt concrete, has been widely applied on pavements. However, the brittle fracture characteristic of cement concrete restricts its application in highway pavement construction. Since the polypropylene fiber can improve the fracture toughness of cement concrete, Polypropylene Fiber-Reinforced Concrete (PFRC) is attracting more and more attention in civil engineering. In order to study the effect of polypropylene fiber on the generation and evolution process of the local deformation band in concrete, a series of three-point bending tests were performed using the new technology of the digital speckle correlation method for FRC notched beams with different volumetric contents of polypropylene fiber. The modified Double-K model was utilized for the first time to calculate the stress intensity factors of instability and crack initiation of fiber-reinforced concrete beams. The results indicate that the polypropylene fiber can enhance the fracture toughness. Based on the modified Double-K fracture theory, the maximum fracture energy of concrete with 3.2% fiber (in volume) is 47 times higher than the plain concrete. No effort of fiber content on the strength of the concrete was found. Meanwhile to balance the strength and resistant fracture toughness, concrete with 1.6% fiber is recommended to be applied in pavement construction.

• 한국ITS학회 논문지
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• 제9권6호
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• pp.54-62
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• 2010

차 대 보행자 교통사고는 다른 유형의 사고에 비해 피해가 매우 크고 사고의 비중도 높으나 사고의 특성 상 과학적 접근이 어렵다. 기존 보행자 사고에 관한 연구의 대부분은 차 대 보행자의 충돌 실험에 대한 실험식 도출에 집중되어 있고, 실험식에서 중요한 변수로 작용되는 인체 활주 마찰 계수에 대한 연구가 부족한 실정이다. 본 연구에서는 인체와 노면간의 마찰계수에 대한 현장실험을 실시하여 이에 대한 실험값을 측정하여 제시하였다. 본 연구에서 조사된 인체노면 마찰계수 값은 건조한 아스팔트 도로에서 0.59~0.62, 건조한 콘크리트 도로는 0.59~0.61로 측정되었다. 또한, 젖은 아스팔트와 콘크리트 도로에서는 각각 0.56~0.59, 0.51~0.54로 나타나 건조한 노면 상태와 비교하여 5.0%와 8.3% 감소하는 것으로 파악되었다. 도출된 마찰계수를 시뮬레이션 프로그램을 이용하여 검증한 바, 실험 수치와 시뮬레이션 결과가 유사함을 확인하였다. 본 연구결과를 활용하여 국내 교통사고 조사 시 사용되는 인체 마찰계수의 적용 값의 범위를 축소할 수 있고, 이는 사고 조사의 정확성 향상에 큰 도움을 줄 것으로 기대한다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2009년도 추계 학술논문 발표대회
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• pp.175-178
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• 2009

This study is thing for construction properties that protect about damage of waterproofing course that is problem in asphalt pavement and latex modification concrete pavement. It is thing about new method of construction and develop protecting material of waterproofing. Did performance test item first at, as a result, drew by suitable thing in all KS items, This is considered to have more effective spot construction work because if means that have stability by material as well as method construction.

• 한국방재학회 논문집
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• 제8권5호
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• pp.65-70
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• 2008

변형과 파손 등의 공용성능 문제가 발생하고 있는 아스팔트 포장과 콘크리트 포장에 비해 내구성능이 우수한 에폭시와 세라믹스를 결합한 혼합물을 도로포장에 적용하기 위하여 실내물성실험을 수행하고 현장에 적용하였다. 본 연구는 부착력과 내구성이 뛰어나 구조물 보수, 보강에 널리 사용되는 에폭시를 도로포장에 적용하기 위해서 세라믹스와 금속성분 등의 micro powder를 첨가하여 포장 재료로써의 공용성능을 확인하고 이를 현장에 적용하여 작업성과 시공성 등을 확인하였다. 콘크리트포장 현장의 시험시공은 파손된 기존 포장구간에 면처리 후 7 mm 박층으로 시공하였고, 아스팔트포장 현장의 시험시공은 파손된 기존 포장구간에 면처리 후 15 mm 박층으로 시공하여, 12개월 가량 균열 및 변형 발생여부를 관찰하였다. 에폭시와 세라믹스를 결합한 혼합물은 기존 포장과의 부착력이 뛰어났으며, 변형과 파손에 대한 저항성이 기존 포장재료에 비해 우수한 것으로 나타나 이를 도로현장에 적용할 경우, 공용성능 및 공용년한의 향상이 기대된다.

• 한국도로학회논문집
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• 제20권1호
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• pp.87-95
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• 2018

PURPOSES : A geo-grid pavement, e.g., a stress-absorbing membrane interlayer (SAMI), can be applied to an asphalt-overlay method on the existing surface-pavement layer for pavement maintenance related to reflection cracking. Reflection cracking can occur when a crack in the existing surface layer influences the overlay pavement. It can reduce the pavement life cycle and adversely affect traffic safety. Moreover, a failed overlay can reduce the economic value. In this regard, the objective of this study is to evaluate the bonding properties between the rigid pavement and a SAMI by using the direct shear test and the pull-off test. The predicted fractural energy functions with the shear stress were determined from a numerical analysis of the moving average method and the polynomial regression method. METHODS : In this research, the shear and pull-off tests were performed to evaluate the properties of mixtures constructed using no interlayer, a tack-coat, and SAMI with fabric and without fabric. The lower mixture parts (describing the existing pavement) were mixed using the 25-40-8 joint cement-concrete standard. The overlay layer was constructed especially using polymer-modified stone mastic asphalt (SMA) pavement. It was composed of an SMA aggregate gradation and applied as the modified agent. The sixth polynomial regression equation and the general moving average method were utilized to estimate the interlayer shear strength. These numerical analysis methods were also used to determine the predictive models for estimating the fracture energy. RESULTS : From the direct shear test and the pull-off test results, the mixture bonded using the tack-coat (applied as the interlayer between the overlay layer and the jointed cement concrete) had the strongest shear resistance and bonding strength. In contrast, the SAMI pavement without fiber has a strong need for fractural energy at failure. CONCLUSIONS : The effects of site-reflection cracking can be determined using the same tests on cored specimens. Further, an empirical-mechanical finite-element method (FEM) must be done to understand the appropriate SAMI application. In this regard, the FEM application analy pavement-design analysis using thesis and bonding property tests using cored specimens from public roads will be conducted in further research.

• 한국도로학회논문집
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• 제15권2호
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• pp.11-18
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• 2013

PURPOSES : This study presents the noise level and frequency characteristics investigated in the national highways with the consideration of various measuring conditions and/or methods. METHODS : The noise levels on the asphalt concrete pavement(ACP) and the jointed plain concrete pavement(JPCP) of the national highway were measured and analysed with respect to three variables, i.e., pavement type, surface condition, and measurement distance. The PASS-By method is utilized for the noise measurement and then using CPB spectrum analysis method with 1/3 octave bandwidth, the noise levels and frequency characteristics were calculated for two-second periods before and after the peak noise. RESULTS : Depending on the pavement type, the noise level was changed as the average noise levels are 73.3dB(A) and 78.3dB(A) for ACP and JPCP, respectively. With respect to the effect of surface condition, the average noise levels for crack H(high), M(medium), and L (low) sections are 77.4dB(A), 77.4dB(A), and 78.1dB(A), respectively. Regarding the measurement distance, 1.2meter difference in measuring location reduces 1.6dB(A) of noise level; the average noise levels at 5.3m and 7.5m from the centerline of outer lane are 72.8dB(A) and 71.2dB(A), respectively. It should be noted that the noise levels are slightly different as a function of vehicle speed and type. However, the overall trends for each case was similar. It was found that the domain frequency bands for ACP and JPCP were 400Hz~2000Hz and 500Hz~2000Hz, respectively. CONCLUSIONS : Based on the analysis with the measured noise date from national highway, it was concluded that the noise level and frequency band vary depending on the various conditions. It was also found that some variables significantly affect the noise level while others do not. With further systematic investigation, the comprehensive noise characteristics on the national highway can be achieved. Using such database, it is possible to develop the fundamental noise reduction technology.

• 대한토목학회논문집
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• 제35권4호
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• pp.931-940
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• 2015

롤러전압콘크리트(Roller Compacted Concrete Pavement, RCCP) 공법은 적은 단위수량이 포함된 콘크리트 혼합물을 아스팔트 피니셔와 다짐 롤러를 이용하여 시공하는 공법이다. RCCP는 다짐 수준에 따라 강도 및 내구성에 많은 영향을 받게 된다. 또한 품질관리는 건조밀도를 기준으로 다짐도 관리를 시행하고 있다. 현장에서 최적의 건조단위중량을 모사하기 위해 수정다짐시험을 실시한다. 그러나 RCCP를 위한 수정다짐시험의 다짐곡선 분석에 명확한 기준이 제시되어 있지 않다. 본 연구에서는 함수비당 세 개의 샘플에 의한 수정다짐곡선의 기준을 설정하고 설정된 다짐곡선과 비교하여 더 적은실험횟수와의 신뢰성을 분석하기 위해 반복재현성을 고찰하였다. 이로 인해 세 번의 실험에 의한 수정다짐시험과 비교하여 두 번의 수정다짐시험은 0.5% 오차가 발생되며 신뢰도는 99.5% 이다.