산업 발전에 따라 도로 연장이 지속적으로 증가하면서 폐 아스팔트 발생량이 늘어나자, 국내에서는 순환골재를 의무적으로 사 용하도록 관련 규정을 마련하였다. 현장 플랜트에서 순환 아스팔트 혼합물을 생산할 때 재생첨가제를 투입해야 하는 경우, 국 토교통부 “아스팔트 콘크리트 포장 시공 지침“에서는 재생첨가제와 아스팔트를 동시에 투입하도록 명시하고 있다. 그러나 혼합 시간이 부족하거나 혼합 과정이 불량할 경우, 재생첨가제가 균일하게 분산되지 않아 혼합물 품질이 저하될 우려가 있다. 이에 본 연구에서는 기존의 건식 혼합 방식에서 발생하는 문제점을 해소하고자, 아스팔트 플랜트의 Pre-Mixer를 활용하여 아스팔트 바인더와 첨가제를 사전에 혼합하고, 혼합 시간을 달리한 시료를 추출하여 DSR(Dynamic Shear Rheometer) 장비를 통한 MSCR 시험을 수행하였다. 그 결과, 혼합시간이 증가함에 따라 Jnr 값은 증가하고, %Recovery 값은 감소하는 경향이 확인되었 으며, 혼합 시간이 바인더 특성 변화에 유의미한 영향을 미치는 것을 확인하였다. 추가적으로 t-검정을 통해 이러한 경향의 통 계적 유의성을 검증한 결과, Jnr 값은 3-5분, 7-9분, %Recovery 값은 1-3분, 3-5분, 7-9분 구간에서 p값이 0.05 이상으로 나타 나 통계적으로 유의미한 차이가 없었다.

This study aims to reduce the use of chloride-based deicers by analyzing their residual quantities on road surfaces. The freezing conditions of road surfaces were quantitatively defined using needles of consistent weight and diameter, and indoor experiments were conducted to observe changes in surface conditions caused by residual deicers under various temperatures. To validate the equipment, a deicer currently used in Korea was applied to granite plates, and the correlation between the application rates and salinity measurements obtained using the SOBO3+ device was analyzed. Subsequently, the device was employed to measure salinity changes over time by assessing the variations in residual deicer quantities on roads with different traffic volumes and application rates. To identify issues in current reapplication methods, the deicer was reapplied at 2-h intervals, and the resulting changes in salinity were monitored. Results of laboratory experiments revealed that the interval for surface state changes decreases with the temperature despite increased deicer usage, and that similar surface change patterns are presented at higher (-2 °C, -4 °C) and lower temperatures (-6 °C, -10 °C). Across all temperatures, the coefficient of determination for the surface-change graph is approximately 0.90. Equipment verification shows that 10% of sodium chloride is underestimated, whereas aqueous calcium chloride is accurately measured and no correlation is indicated between measurement accuracy and road surface temperature. Field experiments confirmed that the deicer dispersion rates increases with the traffic volume. Furthermore, the final salinity increases after the reapplication of the deicer, except in cases of high traffic volume, and that repeated applications with reduced spray amounts are more effective than single applications with higher spray amounts under low traffic conditions. Based on the findings obtained, a plan to reduce deicer usage is proposed. Future research should incorporate additional variables that affect deicer loss and surface condition changes to further refine the results.

This study evaluates adhesion strength under various conditions to ensure adhesion performance during asphalt-pavement maintenance. The adhesion performance of a tack coat varies under various conditions. Therefore, to evaluate its curing behavior, several tests, i.e., evaporation residue rate, tracking, tack-lifter, and shear bond strength tests, were conducted based on the type, amount, and curing time of the tack coat.The result of the evaporation residue rate test shows that, except for the SSC tack coat, RSC-4 and modified tack coats require similar curing times, even though the modified tack coats have a lower moisture content. Additionally, based on the evaporation residue rate, the tracking and track-lifter test results show that approximately 75% curing is required to prevent the loss of the tack coat during asphaltpavement maintenance. After maintenance work is completed, the shear bond strength was measured to evaluate the curing properties of the tack coat. The results show that the amount applied, curing degree, and shear bond strength are proportional, whereas the modified tack coat indicate a significant difference in the strength increase rate depending on the curing degree. Additionally, when dust is attached to the surface of the tack coat, the difference in strength exceeds 20%, depending on the attachment ratio.To achieve the best adhesion performance by the tack coat during maintenance work, the loss of the tack coat should be prevented by implementing the exact curing time determined experimentally, regardless of whether the tack coat is modified, and the surface where the tack coat is applied should be cleaned before application.

This study investigated the tracking loss rate and shear bond strength under various conditions to evaluate the properties of a trackless tack coat used in asphalt pavement maintenance and conducted a field investigation in which the trackless tack coat was used. Typically, the loss rate and bond strength of a tack coat depend on various conditions. Therefore, to evaluate the loss rate of the tack coat, a wheel-tracking attachment loss rate and tack lifter test were conducted by simulating high-temperature exposure conditions, and the shear bond strength was measured according to the surface condition of the bottom layer. In addition, field investigations of cracks, rutting, and potholes were conducted at 11 sites five years after the application of the trackless tack coat. The results of the wheel-tracking loss rate evaluation showed that the loss rate differed depending on the conditions of the bottom layer, and the loss rate of the trackless tack coat was very low at the same temperature as that of the rapid strength concrete (RSC). In addition, in the results of tack lifter test at 65℃, which had the highest loss rate by wheel tracking loss rate test, it was found that loss rate of trackless tack coat was 0%–29% lower than that of RSC for the same exposure time. As a result of evaluating the effect of the bottom layer's condition on the shear bond strength, it was found that the trackless tack coat was about 20% higher than RSC under the same conditions. In addition, when foreign substances such as dust were present in the bottom layer, the shear bond strength was reduced by approximately 28%. Field investigations of the trackless-applied section showed that potholes and rutting did not occur, and alligator cracks and linear cracks occurred in some sections; however, it was judged that there was little direct relationship with the trackless tack coat. The trackless tack coat was found to have a slight loss owing to tracking, even at relatively high temperatures, and the shear bond strength was excellent. In addition, if the construction process is properly conducted, an advantage will be attained in securing the performance life of asphalt pavements.

Pavements have historically been used for mobility, but their usage in cities is steadily increasing owing to social and cultural development. Urban development is rapidly accelerating, primarily because of the concentration of the urban population. Additionally, the effects of the urban heat island are intensifying owing to global warming. One of the main factors contributing to this phenomenon is the increase in impermeable layers, such as asphalt and concrete pavements, in city centers. Various technological developments have been conducted to reduce the effects of urban heat islands. This study developed a moisture-retaining asphalt that absorbs moisture by incorporating a highly super-absorbent polymer (SAP) into a porous asphalt mixture, with the aim of alleviating the urban-heat-island effect. The porous asphalt mixture was designed accordingly. When the mixing design was completed, tests for the tensile strength ratio (TSR), asphalt wheel tracking, and indoor water permeability were conducted on the porous asphalt. Moreover, Hamburg wheel tracking and dynamic water acupuncture tests were performed to evaluate the compatibility of SAP moisture-retaining asphalt, and the results were as follows: Depending on the type and content of SAP, we confirmed that the TSR and permeability coefficient decreased as the amount of SAP increased, resulting in a decrease in durability. In addition, thermal characteristics and simulations showed that the SAP asphalt mixture would have a heat island reduction effect. In this paper, guidelines for the blending design of SAP moisture-retaining asphalt are presented with the aim of alleviating the urban heat island phenomenon by ensuring durability while simultaneously reducing surface temperatures.

동절기에 시민들의 안전 및 편리성을 위하여 도로 유지 보수는 필수적이다. 유지 보수 중 도로의 눈 및 얼음을 제거하기 위해서는 제설제를 살포하는 것이 가장 일반적이다. 하지만, 국내의 제설제 재살포 시기 및 양에 대해서는 연구된 바가 존재하지 않는 실정이기 때문에 제설제 살포 후 녹은 눈이 재결빙이 되는 소요시간이 3시간이라는 점을 참고하여 현재 국내에서는 기후 변화에 관계없이 3시 간마다 초기에 살포한 양을 제설제를 살포하거나 현장 감독자의 주관적인 판단으로 제설제 살포량을 결정하여 제설제 살포를 실시하 고 있다. 이렇게 무분별한 제설제 살포는 과다 살포로 이루어져 환경 및 구조적 문제를 야기할 수 있으며 위 문제를 해결하기 위해서 는 도로에 잔존하고 있는 제설제의 양을 파악하고 무분별한 제설제 살포를 막아야할 필요가 있다. 따라서 본 연구에서는 도로에 물을 살포하여 전기전도도를 이용하여 염분을 측정하는 장비인 SOBO3+를 이용하여 도로의 잔존염분량을 측정하기 전, 국내 고속도로에서 사용되는 제설제와 SOBO3+ 장비와의 상관 관계를 분석하여 장비 검증을 실시하였다. 실험은 국내에서 가장 많이 사용되는 살포 방법 인 습염식 살포 방법을 참고하여 고형 염화나트륨과 30% 염화칼슘 수용액을 사용하였으며 정확한 염분 측정치를 얻기 위하여 매끄러 운 화강판 및 고형 염화나트륨을 모두 용해시켜 측정을 진행하였다. 제설제 살포량은 염화나트륨의 경우 SOBO3+가 최대 50g/m² 까지 밖에 측정이 가능하다는 점을 참고하여 10~50g/m² 범위에서 살포 밀도를 10g/m²씩 변화시켜가며 측정한 결과, 살포량 대비 약 10% 과 소평가되어 측정됨을 확인하였다. 또한 염화칼슘 수용액의 경우 국토교통부 도로제설업무수행요령을 참고하여 국내 습염식 살포 기준 에서 염화칼슘 수용액 살포량이 최대 20g/m²을 초과하지 않아, 10~30g/m² 범위에서 살포 밀도를 10g/m²씩 변화시켜가며 측정한 결과, 살포량 대비 약 70% 과소 평가 되는 것을 확인하여 30% 염화칼슘 수용액을 정확하게 측정하는 것을 확인하였다. 또한 노면 온도가 측정 성능에 영향을 미치지 못하는 것을 확인하였다.

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.

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 : The process of extracting and recovering an asphalt binder from an asphalt mixture is harmful to the human body and can affect the properties of the asphalt binder owing to the presence of residual solvent quantities. This study was conducted to determine the properties of aged asphalt binders based on rejuvenator content without extracting and recovering the asphalt binders using RAP mortar. METHODS : After extracting and recovering aged binders from waste asphalt, a rejuvenator was added at a certain rate to evaluate the physical and rheological properties of the binder based on the added amount. RESULTS : When the rejuvenator content was greater than necessary, the absolute viscosity was not properly measured owing to the behavior of the rejuvenator. The phase angle was measured to be almost 90°, thus indicating that it acted as a liquid . In addition, the shear strain and nonrecovery compliance also increased significantly. CONCLUSIONS : If an excess rejuvenator quantity was added to the aged binder, the absolute viscosity was not properly measured, the phase angle was measured to be almost 90°, and the shear strain increased significantly. It is also necessary to conduct the same tests on different types of RAPs to ensure that the results of this study are reasonable.

PURPOSES : The purpose of this study is to evaluate the asphalt binder properties using FTIR analysis. METHODS : To investigate the chemical properties of asphalt binders, FTIR tests were performed. Recently, FTIR was used for quantification under various aging conditions. Three scans were averaged for each sample within the wavenumber range of 4000 to 400 cm-1, at a resolution of 4 cm-1 (default Simatech software settings). To determine the oxidation of the extracted asphalt binder and the remaining TCE solution in the extracted asphalt binder, the penetration test was adopted and compared. To track the changes in the chemical composition of the aged bitumens, the ATR spectrum of each sample was analyzed, both qualitatively and quantitatively. The qualitative analysis involved identifying characteristic absorption peaks for the functional group of interest, such as polymer components, carbon and sulfur oxidation products, and polar aromatics. RESULTS : The asphalt binder is easily oxidized in air during FTIR testing. To reduce the oxidization of the asphalt binder, the asphalt binder must avoid air contact to measure constant results. Sometimes, the extracted asphalt binder has a residual solvent (TCE), which affects the evaluation of the extracted asphalt binder rheology, such as absolute viscosity and penetration testing. To solve this problem, the research team adopted the FTIR test method. First, the TCE was scanned with FTIR to obtain the chemical characteristics of TCE. After that, the extracted asphalt binder was scanned and the FTIR spectra were compared with those of TCE. If there is a TCE in the extracted asphalt binder, a typical peak was found in the spectrum. Thus, it is possible to estimate the content of the TCE remaining in the extracted asphalt binder via the FTIR test method. CONCLUSIONS : It is possible to evaluate the aging of asphalt binder through FTIR analysis used for the analysis of the chemical structure of asphalt. In addition, during FTIR analysis, the sample is required to avoid air contact to obtain accurate results. FTIR analysis was conducted to confirm whether the solvent (TCE) remained in the extracted asphalt binder and it was confirmed that the penetration increased by a factor of two when the solvent remained. This suggests that it is difficult to control the quality of the asphalt mixture by controlling the amount of recycled additive, as well as the aging of the extracted asphalt binder.

PURPOSES:The purpose of this paper is to evaluate interface performance while using various tack coat materials for asphalt overlay.METHODS:The evaluation was conducted with tracking test, permeability, and interface bond strength. Tracking test was conducted using an image processing technique, to investigate the susceptibility of the tack coat materials. BBS and pull-off test were conducted to evaluate bond strength. The permeability test was conducted to evaluate the effect of tack coat materials.RESULTS :Results reveal that the trackless tack coat material demonstrates less tracking compared to other materials. Moreover, both BBS and pull-off tests can effectively evaluate the bond strength at the interface. RSC-4 was measured less bond strength. Moreover, tack coat prevents water penetration through the surface and aids the extension of the surface life of asphalt pavement.CONCLUSIONS :Trackless tack coat demonstrated a high and consistent bond strength performance. The tack coat types demonstrate marginally different performance as function of curing times. Field applicability was tested based on visual observation. Therefore, these should be considered when trackless tack coat is slightly enhanced the pavement performance based on limited this study results. Finally, it is necessary to allow reasonable time for the tack coat to completely cure.

PURPOSES :This study aims to develop a sealant for use in the installation of Weigh-In-Motion (WIM) sensor for asphalt concrete or cement concrete pavements.METHODS:In order to investigate the properties of various sealants that were mixed with latex and carbon fiber, various test methods were adopted, such as bituminous bond strength test, softening point test, and cone penetration test. To evaluate moisture susceptibility, the BBS test was conducted under moist condition. The bond strength ratio (BSR) was calculated based on tensile strength ratio method.RESULTS :The sealant’s properties significantly varied according to the amount of latex or carbon fiber. The usage of latex marginally enhanced the cone penetration test result, notwithstanding reduced asphalt content. This implies that the sealant will be proper cold temperature reason. Moreover, the addition of latex and carbon fiber evidently increased the softening point. This indicates that the tendency of the material to flow at elevated temperatures is encountered during service. With the addition of latex and carbon fiber, the moisture susceptibility measured with BSR improved marginally, while the bond strength under dry condition decreased marginally. Sealant F displays the highest bond strength and BSR under limited test conditions.CONCLUSIONS :According to the proportion of latex and carbon fiber mixed, properties of sealant, such as softening point, cone penetration, and BSR varied marginally. This indicates that the sealant has to be applied considering the environmental condition, to improve service life.