Evaluation of low temperature performance of asphalt mixture is significant not only for mitigating transverse thermal cracking but also for preventing potential traffic accidents. In addition, the engineers in pavement agency need to inform the proper pavement section where urgent management is needed. Since early 2000, Korea Expressway Corporation Research Division (KECRD) developed an 3D Pavement condition Monitoring profiler vehicle (3DPM) to survey expressway pavement surface condition precisely. The management of whole expressway network became more precise, effective and efficient than before due to application of 3DPM and HPMS. One thing recommended is: performing extensive mechanical test and corresponding data analysis work procedure to further strengthen the feasibility of current 3DPM approach and HPMS. In this paper two activities were considered: first, the pavement section where the urgent care is recommended is selected by means of 3DPM approach. Then asphalt mixture cores were acquired on that specified section then low temperature fracture test: Semi Circular Bending (SCB) test, was performed. The mechanical parameters, energy release rate and fracture toughness were computed then compared. It is concluded that the current 3DPM approach in KEC can successfully evaluate and analyze selected pavement condition. However, more extensive experimental works are needed to further strengthen the current pavement analyzing approaches.

본 연구에서는 국내 아스팔트 도로 현장에서 발생한 동절기 도로융기 현상의 발생 원인을 현장 규명하고 동결융해 피해를 보수하고 자 현장조사, 현장 LFWD실험 및 포장 코어채취, 지하수위 측정, 기상데이터 및 설계자료 분석 등을 실시하였다. 본 연구의 동상 원인 분석은 추후 동결융해 피해 재발방지를 위한 적정한 보수보강공법을 선정하기 위해 수행하였다. 분석과정은 지하수위 상승에 의한 동 상피해 가능성, 동결깊이 과소설계에 의한 동결융해 가능성, 포장면 표면수 유입에 의한 동결융해 가능성, 도로 외측 비포장면을 통한 수분유입과 이에 의한 동결융해 가능성으로 조사하여 동상 원인을 파악하였다. 또한 현장에서 소형충격 재하시험 LFWD(Falling Weight Deflctometer)시험을 하여 포장의 구조적 지지력을 측정하여 얻은 처짐값을 통해 포장체 구조적 능력을 분석함과 동시에 도로융기와의 연관성을 파악하여 균열분석 결과를 함께 분석하고 보수방법을 제안하였다.

PURPOSES : The purpose of this study is to provide basic data to improve the service life of asphalt pavement using basalt aggregate in Jeju Island by evaluating the performance of asphalt pavement through analysis of material and structural aspects. METHODS : To evaluate the performance of Jeju Island's asphalt pavement, cracks, permanent deformation, and longitudinal roughness were analyzed for the Aejo-ro road, which has high traffic and frequent premature damage. Cores were collected from Aejo-ro sections in good condition and damaged condition, and the physical properties of each layer were compared and analyzed. In addition, plate cores were collected from two sections with severe damage and the cause of pavement damage was analyzed in detail. RESULTS : About 45% of the collected cores suffered damage such as layer separation and damage to the lower layer. The asphalt content of surface layer in the damaged section was found to be 1.1% lower on average than that in the good condition section, and the mix gradations generally satisfied the standards. The density difference between the cores of each layer was found to be quite large, and the air voids was found to be at a high level. CONCLUSIONS : Test results on the cores showed that, considering the high absorption ratio of basalt aggregate, the asphalt content was generally low, and the high air voids of the pavement was believed to have had a significant impact on damage. High air voids in asphalt pavement can be caused by poor mixture itself, poor construction management, or a combination of the two factors. Additionally, the separation of each layer is believed to be the cause of premature failure of asphalt pavement.

PURPOSES : This study is aimed to economic analysis of the ferronickel slag pavement method carried out to suggest the necessity of developing ferronickel slag pavement technology. METHODS : A life cycle cost analysis of the application of the Ferronickel Slag pavement method and the cutting + overlay pavement method was performed to compare the economic indicators and greenhouse gas emissions for each pavement method. RESULTS : As a result of the analysis, regardless of the Ferronickel Slag mixing rate, if the common performance of the Ferronickel Slag pavement method is the same or superior to the existing pavement method, it is more economical than the existing pavement method. Furthermore, the lower the maintenance cost of the Ferronickel Slag pavement method, the higher the economic feasibility due to the high Ferronickel Slag mixing rate. Greenhouse gas emissions can be reduced from at least 9% to up to 53% through the application of the Ferronickel Slag pavement method, except for some scenario analysis results. CONCLUSIONS : This study provided that the Ferronickel Slag pavement method was superior to the existing pavement method in terms of economic and environmental aspects. Therefore, it was found that the objective justification of developing road pavement technology using Ferronickel Slag was secured.

The asphalt concrete industry, accounting for >90% of road pavement, is a crucial contributor to construction waste. This study focuses on the recycling of asphalt concrete recycled aggregates, which currently exhibits a low rate. We investigated the application of these aggregates, combined with hardener and mixing water, in the development of ecofriendly road base materials using circular aggregates. Results revealed that the 13-mm asphalt concrete recycled aggregates met all quality standards. However, the 25-mm aggregates did not conform to the reclaimed asphalt content standard; however, they met other quality standards. Moreover, the experimental results for the hardener and mixing water indicated compliance with all quality standards.

PURPOSES : The evaluation of the low-temperature performance of an asphalt mixture is crucial for mitigating transverse thermal cracking and preventing traffic accidents on expressways. Engineers in pavement agencies must identify and verify the pavement sections that require urgent management. In early 2000, the research division of the Korea Expressway Corporation developed a three-dimensional (3D) pavement condition monitoring profiler vehicle (3DPM) and an advanced infographic (AIG) highway pavement management system computer program. Owing to these efforts, the management of the entire expressway network has become more precise, effective, and efficient. However, current 3DPM and AIG technologies focus only on the pavement surface and not on the entire pavement layer. Over the years, along with monitoring, further strengthening and verification of the feasibility of current 3DPM and AIG technologies by performing extensive mechanical tests and data analyses have been recommended. METHODS : First, the pavement section that required urgent care was selected using the 3DPM and AIG approaches. Second, asphalt mixture cores were acquired from the specified section, and a low-temperature fracture test, semi- circular bending (SCB) test, was performed. The mechanical parameters, energy-release rate, and fracture toughness were computed and compared. RESULTS : As expected, the asphalt mixture cores acquired from the specified pavement section ( poor condition – bad section) exhibited negative fracture performances compared to the control section (good section). CONCLUSIONS : The current 3DPM and AIG approaches in KEC can successfully evaluate and analyze selected pavement conditions. However, more extensive experimental studies and mathematical analyses are required to further strengthen and upgrade current pavement analysis approaches.

PURPOSES : The numeric-based Highway Pavement Management System (HPMS), along with an advanced three-dimensional pavement condition monitoring profiler vehicle (3DPM), in South Korea has presented remarkable advancements in pavement management since the early 2000. Based on these results, visual distress on pavement surfaces can be easily detected and analyzed. Additionally, the entire expressway pavement surface conditions in South Korea can be easily monitored using the current graphical user interface-based advanced information graphic (AIG) approach. Therefore, a critically negative pavement section can be detected and managed more easily and efficiently. However, the actual mechanical performance of the selected pavement layer still needs to be investigated in a more thorough manner not only to provide more accurate pavement performance results but also to verify the feasibility of the current 3DPM and AIG approaches. In this study, the low-temperature performance of the selected asphalt pavement layer section was evaluated to further verify and strengthen the feasibility of the current 3DPM and AIG approaches developed by the Korea Expressway Corporation. METHODS : Based on 3DPM and AIG approach, the positive and negative-riding-quality road sections were selected, respectively. The asphalt material cores were extracted from each section then bending beam rheometer mixture creep test was performed to measure their low-temperature properties. Based on the experimental results, thermal stress results were computed and visually compared. RESULTS : As expected, the asphalt material from the negative driving performance section presented a poorer low-temperature cracking resistance than that from the positive driving performance section. CONCLUSIONS : Current 3DPM equipment can successfully evaluate expressway surface conditions and the corresponding material performance quality. However, more extensive experimental studies are recommended to verify and strengthen the findings of this study

PURPOSES : In this study, the thermal conductivity properties and mechanical performance of a thermally conductive asphalt mixture that can be applied to increase the efficiency of deicing asphalt pavements are evaluated. METHODS : Graphite powder and carbon fiber, which are inexpensive carbon materials, were added to the asphalt mixture to its conductivity. To determine the optimal mixing ratio of the carbon materials, the dispersibility, thermal conductivity, and performance of the conductive asphalt mixture were evaluated. The performance of the mixture was evaluated in terms of its volume characteristics, Marshall stability, dynamic modulus, indirect tensile strength (IDT), and wheel-tracking tests. RESULTS : The thermal conductivity of the asphalt mixture containing 2% graphite is 1.81 W/mK, which is approximately twice (0.94 W/mK) that of a general asphalt mixture. Meanwhile, the graphite-added asphalt mixture indicates a much higher temperature increase rate than the general asphalt mixture, and its surface temperature after 60 min is 7.5 ℃ higher. In addition, it reaches 0 ℃ from -10 ℃ at a rate 1.5 times higher than that required by the general asphalt mixture. When both 2% graphite and 1% carbon fiber are added, the thermal conductivity improves to 2.03 W/mK, and the conductivity is similar at all locations of the slab specimen location, which indicates no dispersibility issue. The results of the mechanical performance evaluation shows that the higher the ratio of the carbon material, the lower is the dynamic modulus and IDT at 20 ℃, which decreases the crack resistance. Meanwhile, the results of the Hamburg wheel-tracking test at 50 ℃ show an improvement in the permanent deformation resistance. CONCLUSIONS : The results of the conductivity and performance evaluation show that the optimal ratio is the combination of 2% graphite and 0.5% carbon fiber. This suggests that the conductive asphalt mixture incorporated with carbon materials can efficiently transfer heat generated from the heating layer at the bottom of the pavement to the pavement surface.

Asphalt concrete(Ascon) is used to repair potholes and cracks. Special truck-mounted cargo boxes transport 200℃ asphalt concrete to repair potholes and cracks. However, long working and transportation hours to repair wide roads decrease the temperature of the asphalt concrete inside the cargo boxes. If the asphalt concrete temperature drops below 170℃, the adhesion with roads that need repair decreases. Therefore, the temperature of the asphalt concrete needs to be maintained for a long time. Conventional asphalt concrete cargo boxes are mostly burner-type models using hot air to prevent the temperature of the asphalt concrete from dropping. However, there are significant temperature differences between the asphalt concrete near and far away from the hot air, so the temperature decreases over time and leads to the disposal of large amounts of asphalt concrete. This causes waste of resources and environmental pollution. Therefore, this study proposed a heat dissipation cut-off type cargo box model to solve this problem and demonstrated its performance over conventional burner-type models through tests and analysis.