온실가스 배출량을 최소화하기 위하여 가열 없이 생산이 가능한 상온 아스팔트 포장 공법도 2000년 초부터 개발되어 활용되고 있으 나, 기술적 한계로 인해 성능 확보가 어려워 대부분 기층용으로 활용중에 있다. 상온 아스팔트 혼합물은 유화아스팔트를 사용하는데 양생하는 동안 혼합물 내부에 있는 물이 증가됨에 따라 혼합물 내부의 높은 공극률이 발생하게 되어 포장의 성능을 확보하는데 한계 가 있다. 따라서 본 연구에서는 유화 아스팔트 내 아스팔트 고형분 함량을 증가시켜 물 함량을 최소화함으로서, 양생시간을 단축하고 낮은 공극률 확보를 통한 상온 아스팔트 혼합물의 성능의 변화를 평가하였다. 시험결과, 고형분 함량이 변화에 따라 공극률 및 간접인 장강도, 터프니스 물성이 변화가 나타났다. 하지만 고함량 고형분의 유화 아스팔트를 상온 아스팔트 혼합물에 적용하기 위해서는 최적 함수비 결정방식 및 양생방식 등에 대한 추가적인 연구가 필요한 것으로 나타났다.

본 연구에서는 온도 반응형 발열 아스팔트 포장 공법 개발을 위하여 온도 반응형 신소재의 아스팔트 적용 방안과 이를 아스팔트 재 료에 적용하기 위한 기초 연구를 수행하였다. 발열 아스팔트 포장에 적합한 상변화 온도 범위에 따른 PCM 재료 선정 및 아스팔트 재 료에 적용하기 위한 캡슐화 방안을 검토하고 다양한 소재를 활용한 캡슐화된 PCM 신소재(ePCM)를 제작하였다. 이에 대한 발열 특성 및 물리적 특성 평가를 수행하였다.

최근 결빙으로 인한 교통사고가 빈번히 발생하고 있으며, 도로순찰시 육안 인식이 어려운 도로살얼음 검지를 위해 다양한 방식의 검지센서가 도입되고 있다. 본 연구에서는 국내외 상용화되어 있는 차량부착식 노면상태 검지센서에 대한 현장 검증을 통해 국내 도 로조건에의 적용 가능성을 검토하였다. 차량부착식 검지센서의 성능을 평가하기 위해 한국건설기술연구원의 연천SOC실증연구센터 내 의 도로기상재현 실험시설에 결빙(Ice), 습윤(Wet), 건조(Dry) 등 3가지의 노면상태가 육안으로 명확히 구분이 가능하도록 도로환경을 구현하였으며, 센서종류별로 차량에 부착하여 다양한 도로상태를 측정하였다. 평가결과 노면상태 측정결과의 정확도는 높은 것으로 나 타났으나, 그 외의 측정항목의 정확도는 상당한 차이가 발생하기도 하였다. 향후 다양한 도로환경 조건에서 추가적인 시험을 통해 차 량부착식 노면상태 검지센서의 현장적용을 기반자료로 활용할 수 있을 것으로 판단된다.

최근 급격한 기후 변화로 인해 도로 교통사고의 발생 빈도가 증가하고 있으며, 특히 겨울철에 자주 발생하는 도로 살얼음(블랙아이 스) 현상이 주요 원인 중 하나로 지목되고 있다. 도로살얼음의 형성 메커니즘은 다양한 요인에 따라 복합적으로 작용하며, 당시의 도 로 기상 조건과 도로의 기하학적 구조에 따라 얼음의 형태 및 강도가 결정된다. 그중에서도 도로 노면 온도는 도로살얼음 형성에 중 요한 요소로, 여러 나라에서 겨울철 교통안전 평가를 위한 주요 지표로 사용되고 있다. 그러나 현재 도로 노면 온도에 대한 명확한 정 의가 부족할 뿐만 아니라, 측정 방법에 따라 계측 편차와 온도 손실 등 여러 한계가 존재해 정확한 온도 측정이 어려운 실정이다. 이 에 본 연구는 지중 깊이에 따른 온도 데이터와 도로 기상 데이터를 결합하여 보다 정밀한 도로 노면 온도 예측 방법을 제시하는 것을 목적으로 한다. 연구를 위해 지중 깊이 2cm, 3cm, 4cm, 5cm, 7cm, 9cm, 15cm, 20cm에 각각 온도 센서를 설치하였으며, 기상 데이터는 해당 지점에서 2m 떨어진 AWS(Automatic Weather System)를 통해 대기 온도, 습도, 강수량, 일사량 등의 정보를 수집하였다. 이를 바 탕으로 지중 온도와 기상 조건의 상관관계를 활용하여 노면 온도를 예측하는 방법론을 도출하였다. 본 연구의 결과는 도로 노면 온도 예측의 정확성을 향상시킬 뿐만 아니라, 새로운 접근 방식을 통해 노면 온도의 정의를 재정립하는 데 기여할 것으로 기대된다.

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 : 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 : The purpose of this study is to measure and analyze the fugitive dust generated by each process through field tests to develop a technology to reduce fugitive dust generated during excavation-restoration work on road pavements. METHODS : The testbed was constructed based on a typical excavation-restoration construction section and comprised five sections for reproducibility and repeated measurements. The excavation-restoration work was divided into pavement cutting, pavement crushing, pavement removal, excavation, and restoration processes and fugitive dust generated by each process was measured. Fugitive dust (TSP, PM10, PM2.5, and PM1) was measured using a GRIMM particle spectrometer, which applies the principle of a light scattering spectrometer and can be measured in real-time. RESULTS : Analyses of the average mass concentration of PM10 generated by the excavation-restoration process are as follows: 1286.3 μg/m³ from pavement cutting, 246.8 μg/m³ from pavement crushing, 697.0 μg/m³ from pavement removal, 747.9 μg/m³ from excavation process, and 350.6 μg/m³ from the restoration process. In addition, the average particle size distribution of the excavationrestoration construction was in the order of PM10~PM2.5 (67 %), PM1 or less (24 %), and PM2.5~PM1 (9 %). The pavement cutting process is characterized by the emission of high concentrations of fugitive dust over a short time, compared to other processes. The pavement crushing process has the characteristic of steadily generating fugitive dust for a long period, although the emission concentration is small. CONCLUSIONS : In this study, it was found that the concentration and characteristics of fugitive dust generated during road pavement excavation-restoration works vary by process and the reduction technology for each process should be developed accordingly.

PURPOSES: This study developed a new backfill method for mini trenching. The purpose of this study is to evaluate the performance of the new backfill method in the field. METHODS: In this study, asphalt pavement was created to verify mini trenching. Trenching test sections were then made in various trench widths in the asphalt pavement. The trench widths were 10 cm, 15 cm, 20 cm, and 25 cm. For the trenching test section, a general backfill method and new backfill method (2-layer SCB) were devised and applied. To evaluate the test section, a vehicle loading test and FWD (falling weight deflectometer) test were performed. RESULTS : In the vehicle loading test, the duct vertical strain of the general section was up to 22 times larger than that of the 2-layer SCB section. According to the results of the FWD test, the D0 deflection of the 2-layer SCB section was smaller than that of the general section. These results indicate that 2-layer SCB has a good structural performance. With the use of FWD data, BLI (base layer index) and MLI (middle layer index) were analyzed. BLI is an indirect index for evaluating base layer. The BLI of the 2-layer SCB section was smaller than that of the general section, because the bottom layer (cellular mortar) of the 2-layer SCB is superior to that of the general section. MLI, on the other hand, is an indirect index for evaluating subbase layer. As the trench width increases, MLI increases. The MLI of the 2-layer SCB section was smaller than that of the general section. These results indicate that the damage is relatively greater when the trench width increases and that the 2-layer SCB strengthens a relatively weakened subbase. CONCLUSIONS: In this study, the performance of the 2-layer SCB was analyzed. The results of the study showed that good performance was obtained when 2-layer SCB was applied to a mini trenching section.

PURPOSES: The purpose of this study is to evaluate the mechanical properties of a cold-recycling asphalt mixture used as a base layer and to determine the optimum emulsified-asphalt content for ensuring the mixture’s performance. METHODS: The physical properties (storage stability, mixability, and workability) of three types of asphalt emulsion (CMS-1h, CSS-1h, and CSS-1hp) were evaluated using the rotational viscosity test. Asphalt emulsion residues, prepared according to the ASTM D 7497-09 standard, were evaluated for their rheological properties, including the G*/sinδand the dynamic shear modulus (|G*|). In addition, the Marshall stability, indirect tensile strength, and tensile-strength ratio (TSR) were evaluated for the cold-recycling asphalt mixtures fabricated according to the type and contents of the emulsified asphalt. RESULTS: The CSS-1hp was found to be superior to the other two types in terms of storage stability, mixability, and workability, and its G*/sinδ value at high temperatures was higher than that of the other two types. From the dynamic shear modulus test, the CSS-1hp was also found to be superior to the other two types, with respect to low-temperature cracking and rutting resistance. The mixture test indicated that the indirect tensile strength and TSR increased with the increasing emulsified-asphalt content. However, the mixtures with one-percent emulsified-asphalt content did not meet the national specification in terms of the aggregate coverage (over 50%) and the indirect tensile strength (more than 0.4 MPa). CONCLUSIONS : The emulsified-asphalt performance varied greatly, depending on the type of base material and modifying additives; therefore, it is considered that this will have a great effect on the performance of the cold-recycling asphalt pavement. As the emulsified-asphalt content increased, the strength change was significant. Therefore, it is desirable to apply the strength properties as a factor for determining the optimum emulsified-asphalt content in the mix design. The 1% emulsified-asphalt content did not satisfy the strength and aggregate coverage criteria suggested by national standards. Therefore, the minimum emulsified-asphalt content should be specified to secure the performance.

PURPOSES:The objectives of this study are to evaluate moisture sensitivity of various asphalt mixtures and to suggest an alternate method for the dynamic immersion test, which is used to determine the application of anti-stripping agent, by analyzing bond strength.METHODS:The bond strength of various asphalt mixtures such as hot mix asphalt, warm mix asphalt, and polymer-modified asphalt was evaluated by the ABS test. In order to characterize moisture sensitivity at different temperatures of the mixtures, the ABS test was conducted at -10°C, 5°C, 20°C, 40°C, and 54°C under both dry and wet conditions. The concept of the bond strength ratio was applied for objective moisture sensitivity analysis. Moreover, the bond strength characteristic was compared to the dynamic immersion test to suggest an alternate method to determine the application of anti-stripping agent.RESULTS AND CONCLUSIONS :Overall, the polymer-modified asphalt demonstrates the highest bond strength characteristic regardless of moisture condition and temperature. The bond strength characteristic displays a highly reliable linear relationship from 5°C to 40°C, and the relationship could be used to predict bond strength at any intermediate temperature. Based on the analysis of bond strength and retained asphalt ratio, the bond strength value of 1254 kPa could be applied as a criterion for anti-stripping agent.

OBJECTIVES: The objective of this research is to develop additives for the modification of Solvent DeAsphalting Residue (SDAR) to be used as pavement materials, and evaluate the performance of asphalt mixture manufactured using the SDAR modified by developed additives. METHODS: The SDAR generally consists of more asphaltenes and less oil components compared to the conventional asphalt binder, and hence, the chemical/physical properties of SDAR are different from that of conventional asphalt binder. In this research, the additives are developed using the low molecular oil-based plasticizer to improve the properties of SDAR. First, the chemical property of two SDARs is analyzed using SARA (saturate, aromatic, resin, and asphaltene) method. The physical/rheological properties of SDARs and SDARs containing additives are also evaluated based on PG-grade method and dynamic shear-modulus master curve. Second, various laboratory tests are conducted for the asphalt mixture manufactured using the SDAR modified with additives. The laboratory tests conducted in this study include the mix design, compactibility analysis, indirect tensile test for moisture susceptibility, dynamic modulus test for rheological property, wheeltracking test for rutting performance, and direct tension fatigue test for cracking performance. RESULTS : The PG-grade of SDARs is higher than PG 76 in high temperature grades and immeasurable in low temperature grades. The dynamic shear modulus of SDARs is much higher than that of conventional asphalt, but the modified SDARs with additives show similar modulus compared to that of conventional asphalt. The moisture susceptibility of asphalt mixture with modified SDARs is good if, the antistripping agent is included. The performance (dynamic modulus, rutting resistance, and fatigue resistance) of asphalt mixture with modified SDARs is comparable to that of conventional asphalt mixture when appropriate amount of additives is added. CONCLUSIONS: The saturate component of SDARs is much less than that of conventional asphalt, and hence, it is too hard and brittle to be used as pavement materials. However, the modified SDARs with developed additives show comparable or better rheological/physical properties compared to that of conventional asphalt depending on the type of SDAR and the amount of additives used.