• 한국도로학회논문집
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• 제16권2호
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• pp.53-59
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• 2014

PURPOSES : This study estimated an asphalt pavement internal behavior under uphill lanes considering reducing speed of heavy truck on uphill slope. METHODS : Truck performance curve which has been adapted to "Korea Highway Capacity Manual" was analyzed. And asphalt pavement internal behaviors were estimated with Multi-layered elastic analysis using KPRP(Korea Pavement Research Program) dynamic modulus prediction equations. RESULTS : As a result, it is shown that when the standard truck drives 2.0 km at a speed of 80 km/h in 8% climbing slope, it's speed reduced to 25.4 km/h, at same time frequency in asphalt layer decrease to 67.2% and it's dynamic modulus degrades to 30.9%. Based on these results, internal behavior as decreasing vehicle speed on uphill lanes were estimated. CONCLUSIONS : From the results of Multi-layered elastic analysis, internal behavior showed that when the standard truck drives 2.0 km at a speed of 80 km/h in 8% slope on uphill lanes, vertical strain was increased to 44.4% at the bottom of surface course, and lateral tensile strain was increased to 20.5% at the bottom of base course.

• 한국농공학회논문집
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• 제60권6호
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• pp.111-119
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• 2018

The air-void is known to be one of the influencing factors for estimating long-term performance of asphalt concrete. Most of all, confirming air void or density of pavement layer is important for quality control of field compaction level of asphalt concrete pavement. In this study, a non-nuclear type non-destructive density gage (NDDG) was used to estimate compacted air-voids of asphalt pavement as a non-destructive test method. Asphalt concrete slab specimens were prepared using 6 types of asphalt mixes in laboratory (lab) for lab NDDG test. Four different base structure materials were used to find out if there were any differences due to the type of base structure materials. The actual air-voids and NDDG air-voids were measured from 6 asphalt concrete slabs. Four sections of field asphalt pavements were tested using the NDDG, and actual air voids were also measured from field cores taken from the site where the NDDG air-void was measured. From lab and field experimental tests, it was found that the air-voids obtained by NDDG were not the same as the actual air-voids measured from the asphalt concrete specimen. However, it was possible to estimate air voids based on the relationship obtained from regression analysis between actual and NDDG air voids. The predicted air-voids based on the NDDG air-voids obtained from 50mm depth were found to be reliable levels with $R^2{\fallingdotseq}0.9$. Therefore, it was concluded that the air-voids obtained from NDDG could be used to estimate actual air-voids in the field asphalt pavement with a relatively high coefficient of determination.

• 한국도로학회논문집
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• 제15권4호
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• pp.85-94
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• 2013

PURPOSES: The performance of tack coat, commonly used for layer interface bonding, is affected by application rate and curing time. In this study, bonding strength tests were performed according to the application rate and curing time of asphalt emulsion. Based on finding from this study, optimum application rates and curing times are proposed. METHODS: In order to investigate bonding characteristic of asphalt emulsion, tests were performed on both asphalt concrete pavement and portland concrete pavement. Also, asphalt emulsions were tested at the application rate of 0, 0.2, 0.4, 0.6, and $0.8{\ell}/m^2$ and at the curing time of 0, 0.5, 1, 2, and 24 hours. Pull-off test and shear bonding strength test, which commonly used for bonding strength measurement of asphalt emulsion, were adopted for this study. To assess field performance under different testing condition, asphalt emulsions were applied to in-service pavement. Throughout coefficient of determination analysis between material index properties from asphalt emulsion and mechanical response from bonding strength tests, performance correlativity was analyzed. RESULTS: Test results show that optimum application rate for asphalt overlay on asphalt concrete pavement (AOA) and asphalt overlay on concrete pavement (AOC) was $0.4{\sim}0.5{\ell}/m^2$ and $0.3{\sim}0.5{\ell}/m^2$, respectively. According to the curing time increment, tensile strength and shear strength of AOC were increased to 22~44% and 20~39%, respectively. AOA case also show strength increment in tensile strength (42%) and shear strength (9%). We tested the applicability of tack coat materials at the field sites, and our findings demonstrated that the bonding (for D and E) and rapid curing (for B, C, and D, E) performances were superior than others. Among material index properties, there was a high correlation between penetration ratio and bonding strength test result. CONCLUSIONS : Result show that interlayer bonding strength was affected by asphalt emulsion type, application rate and curing time. AOC required slightly higher application ($0.1{\ell}/m^2$) than AOA. Both AOA and AOC cases show higher strength at longer curing time. Up to 2hours of curing, rapid strength increments were observed, but strength increment ratio was decreased after 2hours of curing. From the observed correlation between penetration ratio and bonding strength, it is expected that penetration ratio can be used as one of important factors affecting bonding strength analysis.

• 한국도로학회논문집
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• 제5권2호
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• pp.1-14
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• 2003

본 연구는 도로 포장에 자체 융설 아스팔트 혼합물의 적용을 위해, 융빙특성을 분석하는 기초연구의 일환으로 수행되었다. 본 연구의 목적은 이러한 문제점을 해결하기 위해 아스콘 제조시 지속성있는 융설제를 첨가하여 높은 융설기능을 유지하도록 한 아스팔트 혼합물을 개발하고 이에 대한 융빙(설) 특성 및 아스팔트 포장으로서의 역학적 특성을 알아보는데 있다. 결합재로는 AC 60-80이 사용되었고, 본 연구에서 개발된 융설제와 CRM이 건식 혼합방법으로 사용되었다. 기존 포장위에 박층포장 용도로 사용하기 위한 샌드 융설 아스팔트 혼합물과 표층용 혼합물과 동일 용도인 13mm 밀입도 융설 아스팔트 혼합물을 개발하였다. 아스팔트 혼합물의 특성을 평가하기 위하여 마샬안정도와 간접인장강도, 결빙 및 융빙실험, 용출수의 수질분석 실험을 수행하였다 융설 아스팔트 혼합물은 포장용 혼합물로서의 충분한 강도 및 우수한 융설 기능도 가지고 있는 것으로 나타났으며, 용출수의 중성화를 유도하여 도로 주변의 식생에도 악영향을 미치지 않을 것으로 판단된다.

• 대한토목학회논문집
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• 제7권2호
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• pp.9-20
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• 1987

아스팔트포장(鋪裝) 공용성(供用性)을 저하(低下)시키는 하나의 원인(原因)으로 피로균열파괴(疲勞龜裂破壞)를 들 수 있다. 본(本) 연구(硏究)에서는 아스팔트혼합물(混合物)의 피로파괴(疲勞破壞)에 미치는 재료특성(材料特性)의 영향(影響)에 대해서 검토(檢討)를 하고 밀입도(密粒度)아스팔트 콘크리트에 대한 반복(反覆)휨변형율제어어시험(變形率制御試驗)을 하여 피로파괴포락선(疲勞破壞包絡線)을 구(求)했다. 다음에 탄성이론(彈性理論)의 결과(結果)와 피로파괴포락선(疲勞破壞包絡線)으로부터 온도(溫度) 아스팔트층(層)두께 하층(下層)의 탄성계수(彈性係數)와 피로파괴회수(疲勞破壞回數)의 관계를 고찰(考察)했다.

• 한국도로학회논문집
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• 제19권6호
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• pp.37-46
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• 2017

PURPOSES : A composite pavement utilizes both an asphalt surface and a concrete base. Typically, a concrete base layer provides structural capacity, while an asphalt surface layer provides smoothness and riding quality. This pavement type can be used in conjunction with rollercompacted concrete (RCC) pavement as a base layer due to its fast construction, economic efficiency, and structural performance. However, the service life and functionality of composite pavement may be reduced due to interfacial bond failure. Therefore, adequate interfacial bonding between the asphalt surface and the concrete base is essential to achieving monolithic behavior. The purpose of this study is to investigate the bond characteristics at the interface between asphalt (HMA; hot-mixed asphalt) and the RCC base. METHODS : This study was performed to determine the optimal type and application rate of tack coat material for RCC-base composite pavement. In addition, the core size effect, temperature condition, and bonding failure shape were analyzed to investigate the bonding characteristics at the interface between the RCC base and HMA surface. To evaluate the bond strength, a pull-off test was performed using different diameters of specimens such as 50 mm and 100 mm. Tack coat materials such as RSC-4 and BD-Coat were applied in amounts of 0.3, 0.5, 0.7, 0.9, and $1.1l/m^2$ to determine the optimal application rate. In order to evaluate the bond strength characteristics with temperature changes, a pull-off test was carried out at -15, 0, 20, and $40^{\circ}C$. In addition, the bond failure shapes were analyzed using an image analysis program after the pull-off tests were completed. RESULTS : The test results indicated that the optimal application rate of RSC-4 and BD-Coat were $0.8l/m^2$, $0.9l/m^2$, respectively. The core size effect was determined to be negligible because the bond strengths were similar in specimens with diameters of 50 mm and 100 mm. The bond strengths of RSC-4 and BD-Coat were found to decrease significantly when the temperature increased. As a result of the bonding failure shape in low-temperature conditions such as -15, 0, and $20^{\circ}C$, it was found that most of the debonding occurred at the interface between the tack coat and RCC surface. On the other hand, the interface between the HMA and tack coat was weaker than that between the tack coat and RCC at a high temperature of $40^{\circ}C$. CONCLUSIONS : This study suggested an optimal application rate of tack coat materials to apply to RCC-base composite pavement. The bond strengths at high temperatures were significantly lower than the required bond (tensile) strength of 0.4 MPa. It was known that the temperature was a critical factor affecting the bond strength at the interface of the RCC-base composite pavement.

• 한국도로학회논문집
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• 제20권2호
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• pp.57-65
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• 2018

PURPOSES : The study aims to predict the service life of national highway asphalt pavements through deep learning methods by using maintenance history data of the National Highway Pavement Management System. METHODS : For the configuration of a deep learning network, this study used Tensorflow 1.5, an open source program which has excellent usability among deep learning frameworks. For the analysis, nine variables of cumulative annual average daily traffic, cumulative equivalent single axle loads, maintenance layer, surface, base, subbase, anti-frost layer, structural number of pavement, and region were selected as input data, while service life was chosen to construct the input layer and output layers as output data. Additionally, for scenario analysis, in this study, a model was formed with four different numbers of 1, 2, 4, and 8 hidden layers and a simulation analysis was performed according to the applicability of the over fitting resolution algorithm. RESULTS : The results of the analysis have shown that regardless of the number of hidden layers, when an over fitting resolution algorithm, such as dropout, is applied, the prediction capability is improved as the coefficient of determination ($R^2$) of the test data increases. Furthermore, the result of the sensitivity analysis of the applicability of region variables demonstrates that estimating service life requires sufficient consideration of regional characteristics as $R^2$ had a maximum of between 0.73 and 0.84, when regional variables where taken into consideration. CONCLUSIONS : As a result, this study proposes that it is possible to precisely predict the service life of national highway pavement sections with the consideration of traffic, pavement thickness, and regional factors and concludes that the use of the prediction of service life is fundamental data in decision making within pavement management systems.

• 한국방재학회 논문집
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• 제9권1호
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• pp.21-25
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• 2009

본 논문에서는 텍사스 휴스턴에 소재하는 William P Hobby공항의 아스팔트 덧씌우기 포장두께를 설계하기위한 재료 특성화와 구조평가 연구결과에 관한 최근의 사례결과를 나타내고 있다. Hobby 공항의 12R-30L 활주로는 포틀랜드시멘트 콘크리트 포장위에 두꺼운 아스팔트 덧씌우기 층으로 구성되어 있으며 최근 부분적인 표면 밀림 현상이 관측되었다. 아스팔트 혼합물 현장코아 시료를 사용하여 표면 밀림현상 원인을 분석하기 위하여 공기량, 아스팔트 함량 및 골재 입도 분석이 수행되었다. 미연방 항공우주국의 탄성층 해석 프로그램인 LEDFAA가 새로운 아스팔트 덧씌우기층의 포장구조 상태를 평가하기 위하여 사용되었다. 이를 위하여 두 가지의 포장구성 상태가 존재한다고 가정하였다. 즉 PCC 포장위에 아스팔트 콘크리트 덧씌우기층, 그리고 아스팔트 콘크리트 포장. 실험실 시험결과를 근거로 아스팔트 바인더 함유량에 대한 200번째 체 통과 골재비는 $1.1{\sim}2.2$이며 비율이 높을수록 혼합물은 연성을 보이는 것으로 나타났다. 따라서, 12R-30L 활주로의 표면밀림 현상은 과도한 세립골재 함유율로 인한 연성혼합물이 원인인 것으로 나타났다. 구조 평가결과에 의하면 아스팔트 포장으로 포장구조를 가정한 해석 결과는 PCC층에 비하여 좀 더 두꺼운 아스팔트 층일때 더 실질적인 구조적 수명을 나타내었다. 아스팔트층 하부의 PCC포장은 고급기층재료 역할을 수행하기 때문인 것으로 해석된다.

• 한국도로학회논문집
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• 제19권6호
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• pp.57-66
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• 2017

PURPOSES : This study develops eco-friendly asphalt reinforcement materials applicable to bridge deck pavement. The main purpose is to ensure highly reliable quality applicable to structures and the possibility of practical application. The main target of the study is to develop materials that are environmentally friendly and capable of improving performance. METHODS : The application of double-reinforcement fiber improves the performance of the road pavement. 1. We use recycled film for application of sheet-typed reinforcement. 2. We use preprocessing fibers to reinforce the properties of composite pavement materials. RESULTS : The developed products may produce materials that fit the purpose of achieving stability and environmental friendliness. Sheet-typed reinforcements use more than 50% recycled resin. The most important type of damage to the asphalt layer is deflection (plastic deformation). These products have a very high deflection resistance of not less than 6,000 cycles/mm. In addition, all performance is excellent. Thus, it will be easier to access the field in the future. CONCLUSIONS : Fiber-reinforced asphalt pavement showed excellent performance. Sheet-typed reinforcements containing 50% recycling resin produced good performance in terms of functionality as well as environmental friendliness. Thus, enhancing the field applicability will enhance the usability of the reinforcements.

• 한국방재학회 논문집
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• 제9권1호
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• pp.57-64
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• 2009

본 연구의 목적은 국내 대표 아스팔트 혼합물의 소성변형특성을 평가하고, 이를 이용하여 소성변형을 예측할 수 있는 파손모형을 다중회귀분석을 이용하여 개발하는 것이다. 2가지 아스팔트 바인더와 5종의 골재입도를 이용하였고, 2개의 다른 공극률(6%, 10%)로 시편을 제작하였다. 시험은 30, 45, 60 온도에서 3가지 구속하중을 이용하여 삼축압축 반복재하시험을 수행하였다. 이를 이용하여 소성변형에 영향을 미치는 인자를 규명하고 소성변형 예측모델을 개발하고자 한다. 소성변형 시험의 결과를 이용한 소성변형 예측 모델을 다중회귀분석을 이용하여 제안하였으며 모델의 신뢰도를 분석하였다. 회귀분석을 이용한 소성변형 모델은 AASHTO 2002 설계법에서 제시한 예측식을 기본으로 소성변형에 영향을 미치는 인자인 온도, 하중재하횟수, 공극률을 주요 변수로 하였다. 이를 SPSS 통계프로그램을 이용하여 제시하였으며 실제 시험값과 모델의 예측값으로 신뢰도를 분석하였다.