아스팔트는 점성이 높은 도로포장 재료로서 골재와 채움재를 결합시키는 역할을 하는 중요한 재료이다. 아스팔트 콘크 리트는 생산 및 시공 과정에서 혼합물이 장비에 부착되는 현상이 발생하여 생산 효율 및 성능 저하를 유발하기도 한다. 이와 같은 문제를 해결하기 위하여 석유류와 식물성 기름을 부착방지제(Asphalt Release Agent)로 사용하고 있다. 하지 만 석유류는 단시간에 아스팔트를 용해시켜 혼합물의 성능 저하를 유발할 수 있고, 발생하는 유증기로 인해 작업자를 위 험에 노출시킬 수 있다. 식물성 기름은 석유류에 비해 아스팔트에 대한 용해력은 다소 작지만 석유류와 동일한 문제를 야기하며 제품 단가로 인해 높은 비용을 발생시킨다. 이에 따라 아스팔트 혼합물 생산 및 시공현장에서 저독성이며 친환 경적인 부착방지제의 중요도가 상승하고 있다.

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.

내구연한이 도래한 아스팔트 혼합물은 사용자의 주행성 및 안전성 확보를 위해 주기적인 유지·보수를 실시한다. 과거에는 유지·보수 과정에서 발생된 폐아스팔트 혼합물을 각종 건설현장에서 단순 매립재로서 활용하였으나, 재활용 아스팔트 혼합물의 배합설계 기술이 확립된 이후에는 도로포장재료로서의 재활용되어왔다. 하지만 현재 시공된 재활용 아스팔트 혼합물 또한 내구연한이 다가옴에 따라 노화된 재활용 아스팔트 혼합물의 처리방안 수립이 필요한 시점이다. 본 연구에서는 한번 재활용된 아스팔트 혼합물이 기존의 재활용 배합설계법으로 반복적인 재활용이 가능한지 검증해보고자 하였다. 이를 위해 아스팔트 혼합물의 물성을 결정하는 가장 큰 요인 중 하나인 아스팔트의 물성이 노화 및 재생을 반복할때 어떻게 변하는지를 시험을 통해 분석하였다. 아스팔트 바인더의 노화를 모사하기 위해 공용성등급시험에 사용되는 단기노화 장비(Rolling Thin Film Oven, RTFO)와 장기노화 장비(Pressure Aging Vessel, PAV)을 활용하 였다. 노화된 아스팔트의 회생을 위한 재생첨가제 사용량은 국토부 시공지침의 배합설계법을 참고하였다. 실험결과, 노화된 바인더는 회생시 원바인더에 비해  sin는 감소하였으나, 회생된 바인더 간에는 유사한 결과값을 보였다. 반면 단기노화 시료는 회생이 반복 됨에 따라  sin이 감소한 경향을 보였으며, 장기노화시료는 회생이 반복되어도  sin가 유사한 것으로 확인되었다.

교통량이 증가하고 교량과 같은 특수구조물에 아스팔트 포장이 시공되는 사례가 증가함에 따라 일반적으로 사용되는 아스팔트보다 높은 성능을 가진 아스팔트에 대한 수요가 증가하고 있다. 일반 아스팔트 혼합물은 내구연한이 지나면 재생첨가제 등을 사용하여 다 시 도로포장재료로서 재활용할 수 있는 방안이 마련되어 있으나, 개질 아스팔트가 사용된 폐아스팔트 혼합물은 매립재로 사용하는 것 이외에는 별다른 대안이 없는 실정이다. 이에 본 연구에서는 국토부 지침에 규정된 재활용 아스팔트 혼합물 배합설계법을 적용하여 개질 폐아스팔트 혼합물을 재활용할 수 있는지를 검토해보고자 하였다. 이를 위해 개질 아스팔트를 활용하여 혼합물을 제작하였으며, 현장에서 수거되는 폐아스팔트 혼합물의 노화상태를 모사하기 위해 AASHTO R 30을 참고하여 강제 노화를 실시하였다. 노화 및 추출 과정에서 아스팔트의 물성 변화를 확인하기 위해 절대점도, DSR, MSCR 시험을 실시하였다. 시험결과, 추출 후 바인더의 절대점도는 감소하였으나 G*(복합전단계수)와 δ(위상각)은 증가하는 경향을 보였다. 소성변형 저항성을 확인하기 위해 MSCR(다중 응력 크리프 및 회복) 시험을 실시한 결과,  이 2배 가까이 증가하여 소성변형 저항성이 감소한 것을 확인할 수 있었다. 이러한 결과는 추출시 사용 되는 용매가 개질첨가제를 추출하지 못하여 기인한 결과로 판단된다. 따라서 개질 폐아스팔트 혼합물을 재활용하기 위해서는 기존과 는 다른 별도의 배합설계법이 개발되어야 할 것으로 판단되었다.

택코트란 아스팔트 포장 공사 시 기존 아스팔트층과 신설 아스팔트 층 사이에 부착성을 증가시키기 위하여 사용되는 재료이다. 교통 하중으로 인해 포장 경계면에서 수평전단응력 및 수직인장응력이 발생하게 되는데 택코트의 유실, 양생 부족 등의 문제로 접착 성능 이 부족하면 포장층의 분리, 밀림과 같은 도로 파괴가 형상이 나타날 수 있다. 현재 국내에서는 국토교통부 아스팔트 콘크리트 포장 시공 지침에 택코트 살포량에 대한 기준은 존재하지만 기존 및 신설 아스팔트 포장층 사이에 택코트의 접착강도에 대한 기준은 존재 하지 않는 실정이다, 이는 접착강도 특성이 분석되지 않은 택코트를 사용함에 따라 아스팔트 포장의 공용성 측면에서 문제를 초래할 수 있다. 따라서 본 연구에서는 PG등급이 다른 택코트 4종류에 대한 인장 및 전단접착강도를 확인하기 위하여 인장접착강도 시험, 전 단접착강도 시험을 진행하였다. 택코트의 양생정도에 따른 접착강도 특성을 확인해보기 위하여 택코트의 수분이 증발됨에 따라 중량 변화가 없는 상태를 양생 100%로 하여 양생 0%, 50%, 100%로 진행하였으며, 살포량은 국토교통부 아스팔트 콘크리트 시공 지침에 따 라 0.5ℓ/m2로 진행하였다. 사용된 택코트 종류에 관계 없이 양생 정도가 증가함에 따라 접착강도는 증가하는 추세를 보였으며, 인장 및 전단접착강도 시험에 관계없이 초기 양생(양생 0%~50%)보다 양생 50% 이후에서의 더 높게 강도가 발현된 것을 확인하였다. 또한 PG등급이 높은 택코트가 인장 및 전단접착강도에 관계없이 접착강도 성능이 우수한 것을 확인할 수 있었다. 추후 택코트의 종류를 추 가하여 PG등급이 분류가 이루어진 후에 접착강도 시험을 진행하여 결과를 확인할 예정이다.

In the contemporary era, 3D printing technology has become widely utilized across diverse fields, including biomedicine, industrial design, manufacturing, food processing, aerospace, and construction engineering. The inherent advantages of automation, precision, and speed associated with 3D printing have progressively led to its incorporation into road engineering. Asphalt, a temperature-responsive material that softens at high temperatures and solidifies as it cools, presents distinctive challenges and opportunities in this context. For the effective implementation of 3D printing technology in road engineering, 3D printed asphalt (3DPA) must exhibit favorable performance and printability. This requires attributes such as good fluidity, extrudability, and buildability. Furthermore, materials utilizing 3DPA for crack repair should possess high viscosity, elasticity, toughness, superior high-temperature stability, and resistance to low-temperature cracking. These characteristics ultimately contribute to enhancing pavement longevity and ensuring worker safety.

2022년 기준 국내 폐타이어 발생량은 약 37만톤으로 그 중 88.9%인 약 32만 9천톤이 재활용되는 것으로 조사되었다. 하지만 이 중 약 75%가 시멘트소성로용 등 열이용 분야에 사용되었다. 폐타이어는 대부분 고무와 플라스틱으로 이루어져 있기 때문에, 고온에서 분 해되면서 다양한 유해가스와 오염물질이 발생할 수 있고, 이러한 공해물질은 적극적으로 관리되지 않으면 대기오염, 수질 오염 등 다 양한 환경문제를 발생시킬 수 있다. 때문에 친환경적이고 지속적인 재활용에 대한 필요성이 대두되고 있다. 폐타이어 고무 분말을 아스팔트 혼합물의 골재 일부로 치환하여 재활용하는 접근 방식은 환경에 미치는 영향을 완화할 뿐만 아니라 천연 자원의 고갈 측면에서도 긍정적인 영향을 미치는 것으로 판단된다. 따라서 타이어분말을 아스팔트 혼합물에 적용하는 것은 환경 문제를 해결하고 자원 효율성을 높이는 두 가지 이점을 가지고 있다. 폐타이어 분말을 아스팔트 바인더와 아스팔트 혼합물에 적용할 경우 미치는 영향을 평가하기 위하여 DSR, BBR, MSCR 등의 시험 을 진행하였으며, 아스팔트 혼합물 내 폐타이어 분말의 분포를 조사하기 위해 SEM을 실시하였다. 또한 IDEAL-CT와 IDEAL-Rutting 시 험을 통해 아스팔트 혼합물의 성능을 평가하였다.

PURPOSES : In this study, the basis for improving the maintenance method of road pavement in Jeju Island, where deterioration is accelerating, was presented through field construction and analysis of various combinations of maintenance methods. METHODS : Construction was performed on Jeju Island's Aejo Road, which has high traffic and frequent early damage, using various asphalt mixtures mainly applied in Jeju Island, with different maintenance cross-sections depending on the level of repair. The quality and performance of the asphalt mixture collected during construction were evaluated, and MEPDG was used to analyze the service life according to the type and maintenance level of the mixture. RESULTS : While the mixture for the surface layer satisfied the quality standards and had excellent rutting and moisture resistance performance, the asphalt mixture for the intermediate and base layer did not satisfy the quality standards such as air voids, so it was judged that quality control was necessary during production. The section repaired to the base layer was found to be advantageous for the integrated behavior of the pavement and had the best structural integrity. As a result of predicting the service life, the estimated life of the section where only the surface layer was repaired was analyzed to be approximately 7 years, the section where the intermediate layer was repaired was 14.5 years, and the section where the entire section up to the base layer was repaired was analyzed to be 18 years. CONCLUSIONS : In Jeju Island, where deterioration is accelerating, it was analyzed that when establishing a maintenance plan, it is necessary to consider repairing the middle and base floors in order to secure the designed life of 10 years.

PURPOSES : The aim of this study is to investigate the enhancement of performance and the mix design method for asphalt mixtures utilizing ferronickel slag, an industrial by-product METHODS : To enhance the performance of FNS asphalt, waste tire powder (CR) was incorporated, and the characteristics of FNS asphalt aggregate, along with the impact of CR, were evaluated through the mix design process. RESULTS : CR is found to be suitable with a size of 30 mesh, and the optimal usage amount is determined to be 1±0.1% of the mixture weight, considering dense grade asphalt mixture. Volumetric design considering the swelling characteristics of CR is necessary, and a mixing design with a consistent tendency can be achieved only when an appropriate VMA is secured. CONCLUSIONS : The mix design for FNS-R asphalt mixture requires an increase of approximately 1% in VMA compared to conventional dense-graded asphalt mixtures to accommodate the swelling of CR. Additionally, FNS-R asphalt exhibits improved resistance to rutting comparable to modified asphalt and meets quality standards, including stripping resistance.

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 was conducted to evaluate the physical properties of the RAP 50 asphalt mixture containing polymer modified rejuvenator and warm-mix additive to improve the recycling rate of RAP and reduce CO2 emission. METHODS : Mix design of Polymer Modified Warm-mix Asphalt Mixture(RAP 50), and Hot Mix Asphalt Mixture(RAP 30) were produced and the properties of asphalt mixture such as Marshall Stability, ITS, Deformation Strength, TSR, and Dynamic Stability were compared between the two asphalt mixtures. RESULTS : The RAP 50 asphalt mixture showed superior or similar performances compared to the RAP 30 asphalt mixture in all the tests conducted. The results of the Marshall stability and dynamic stability in particular were 13,045N and 3,826 pass/mm, which were 11.37% and 76.7% greater than the RAP 30 asphalt mixture, which indicated that high plastic deformation resistance may be expected. CONCLUSIONS : The results obtained from laboratory tests on the two types of mixtures indicated that the use of polymer modified rejuvenator and warm-mix additive not only allows to increase the proportion of RAP but also improves its properties under lower temperature condition than RAP 30 asphalt mixture. Additionally, it was confirmed that plastic deformation resistance was high and moisture resistance and crack resistance were improved for a RAP 50 asphalt mixture.

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.

PURPOSES : In this study, the resources and energy consumed to produce hot mix asphalt mixtures and hot mix reclaimed asphalt mixtures in asphalt concrete plants were estimated and the emissions from the detailed processes of the production process were evaluated based on TRACI(the tool for the reduction and assessment of chemical and other environmental impacts). METHODS : To estimate the energy consumption of the aggregate drying process, which consumes a significant amount of energy in the production process, an energy consumption calculation model based on the thermal equilibrium equation was used, and the energy consumed for material transportation, storage, and operation of other facilities was cited from the literature. RESULTS : For the system boundary conditions established and the inventory considered, the emissions to produce one ton of hot mix reclaimed asphalt mix are greater than the emissions to produce one ton of hot mix asphalt mix for a number of key impact categories. The process of producing hot mix reclaimed asphalt mixtures was evaluated to consume more resources and energy in the production of recycled aggregates and heating for drying than in the production of hot mix asphalt mixtures, but less resources and energy in the production of binders and natural virgin aggregates and the heating to heat these materials. CONCLUSIONS : The results of the emissions assessment using the life cycle inventory for the production of hot mix asphalt mixtures were generally similar to the results understood in the field and in much of the literatures, confirming the reliability of the methodology. However, in order to evaluate the dominance of specific processes or mixtures, it is believed that the construction of a wide range of inventory databases after inventory redesign is necessary for a specific and rigorous assessment.

PURPOSES : This research assesses the influence of emulsified asphalt on vegetation growth by examining parameters such as moisture content, temperature, pH, electrical conductivity, and analyzing the extent of green coverage using image analysis. METHODS : Within this study, sensors were employed to measure the growth environment of vegetation treated with emulsified asphalt. Furthermore, the analysis of the greening rate through image analysis has been incorporated. RESULTS : Research indicates that emulsified asphalt effectively secures seeds to surfaces and maintains moisture content for an extended period. However, the excessive utilization of emulsified asphalt has been observed to reduce germination and greening rates. CONCLUSIONS : The application of an optimal emulsified asphalt content is presumed to promote vegetation growth. To establish objective, it is imperative to conduct comprehensive research on its long-term structural effects regarding growth, greening rate, and slope when integrated with emulsified asphalt.

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 : There has been increasing interest in South Korea on warm-mix asphalt (WMA) and cold-mix asphalt (CMA) technologies that allow production of asphalt pavement mixtures at comparatively lower temperatures than those of hot-mix asphalt (HMA) for use in pavement engineering. This study aims to evaluate the feasibility of replacing HMA pavement with WMA pavement with the goal of reducing CO2 emissions associated with asphalt production for road construction. METHODS : Changes in the dynamic modulus characteristics of WMA and HMA according to short-term and long-term aging were evaluated. In addition, the effects of water damage were evaluated for short- and long-term aging stages. RESULTS : For WMA, in the process of mixing and short-term aging, early-age dynamic modulus decreased owing to low temperature and reduced short-term aging (STA) time. This could result in early damage to the asphalt pavement depending on the applied traffic load and environmental load. CONCLUSIONS : Mastercurves of the dynamic modulus were used for comparative analysis of WMA and HMA. Compared to the dynamic modulus after STA of HMA, the estimated aging time determined by experiments for WMA to achieve the required stiffness was more than 48 hours, which is equiva-lent to approximately 4 to 5 years real service life when converted. It is considered that further studies are needed for performance optimization to achieve early-age performance of the asphalt mixes.

PURPOSES : In this study, energy-consuming processes in asphalt plants were evaluated, and the drying and mixing processes were characterized using a thermal equilibrium equation-based model to quantitatively estimate the amount of energy consumed during the production of mixtures in asphalt concrete plants. METHODS : An energy consumption model based on the thermal equilibrium equation was used to estimate the energy consumption of the aggregate drying process that consumes the maximum energy; the energy consumed for material transportation, storage, and operation of other facilities was cited from the literature. The results were compared with the actual results obtained for recycled hot asphalt mixtures and recycled warm mix asphalt mixtures, and a sensitivity analysis was performed by varying the conditions. RESULTS : An analysis of the main processes required to produce asphalt mixtures showed that the water content had the largest impact on energy consumption (approximately 80%). This quantitatively supports the opinion of field practitioners that maximum energy is consumed during aggregate drying. Although some discrepancies were observed, the results were found to be reasonable and within the range of typical measurements. CONCLUSIONS : The thermal energy consumption estimation model provides consistent results that reflect the characteristics of the mixture and can be used to derive the thermal energy consumption rates for individual materials, such as aggregates and binders. This can be used to identify the priorities for process optimization within a plant.