도로 관리는 교통 시스템과 국가 경제에 중대한 영향을 미치며, 이에 따라 도로 유지관리는 시민들의 삶의 질을 향상시 키는 데 중요한 역할을 한다. 따라서 체계적인 유지관리는 도로 안전성과 경제적 효율성을 높이는 데 필수적이다. 기존 의 도로 관리 방식은 대부분 반응적이며, 종이 문서를 기반으로 이루어져 정보 손실, 데이터 손상, 검색의 어려움 등의 여러 제한점을 가지고 있다. 이러한 문제를 해결하기 위해 본 논문에서는 3D 모델과 관련 데이터를 일대일 매핑하여 자 동으로 입력할 수 있도록 하는 BIM (Building Information Model)을 활용한 접근 방식을 제안한다. 본 연구는 주로 BIM 생성을 위해 널리 사용되는 Autodesk Revit을 활용하여 3D 도로 모델을 생성하고, 도로의 손상 정보 (길이, 폭, 보수 면 적, 보수 부피, 유지보수 이력 등)를 통합 관리하는 방법을 연구한다. 하지만 Revit은 디지털 정보를 3D 모델에 자동으로 가져오는 기능이 없기 때문에, Visual Programming 도구를 이용하여 유지관리 기록 정보를 BIM으로 자동 입력하는 방 법을 개발하였다. 이를 통해, 사용자가 특정 도로 손상 모델을 선택하면 해당 손상의 통합 이력을 표시할 수 있는 새로 운 통합 이력 관리 시스템을 구축하였다. 이러한 접근 방식은 종이 문서 기반의 기록 방식에서 발생하는 데이터 손상, 기록량 증가, 특정 데이터 검색의 어려움 등의 문제를 해결할 수 있으며, 신속하고 정확한 의사 결정을 지원한다. 본 연 구는 BIM을 활용한 도로의 통합 이력 관리 시스템 구축을 통해 새로운 방향성을 제시한다.

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.

아스팔트는 아스팔텐(Asphaltene)과 레진(Resin), 포화분(Saturates), 방향족화합물(Aromatics)로 구성되어 있고, 레 진, 포화분, 방향족화합물의 혼합물을 말텐(Malten)이라 하며, 아스팔텐이 말텐에 분산되어 있는 형태를 가진 콜로이 드 상태의 혼합물이다. 아스팔트를 조성하고 있는 조성물의 조성비, 온도 변화에 따라 결합 상태 및 내부 구조가 변 화하고, 아스팔트의 물성과 상태 등에 영향을 주어, 아스팔트 혼합물이 고온에서 소성변형(Rutting), 저온에서의 균열 (Crack)등의 파손에 영향을 미친다. 이러한 아스팔트 혼합물의 파손을 방지하기 위하여 SBS(Styrene-Butadiene- Styrene Block Copolymer)와 같은 폴리머를 혼합하여 아스팔트의 점탄성을 향상시키고, 오일류와 같은 첨가제를 활 용하여 저온에서 탄성과 유연성을 증가시킨다. 이와 같이 고온과 저온의 성능을 용도에 맞게 개선한 아스팔트를 개질 아스팔트(Polymer Modified Asphalt)라고 하며, 도로의 품질 및 내구성 향상을 위해 개질아스팔트 포장의 수요가 점 차 증가하는 추세로 아스팔트혼합물의 성능 향상을 위해 오일류를 활용한 폴리머 아스팔트의 물성 변화에 대한 연구 가 필요하다고 판단된다.

구스 아스팔트(Guss Asphalt) 혼합물은 다짐 없이 시공이 가능한 포장재료로, 1970년대부터 강바닥판 교량에 활용되어 왔다. 본 연구 는 박스 구스 아스팔트 혼합물 공용수명 예측 및 생애주기 비용을 비교분석하기 위해 폴리머 개질 구스, TLA 및 SMA 세 가지 혼합 물의 반사균열 시험, 동탄성계수 시험 및 소성변형시험을 수행하였다. 또한, TxACOL 프로그램을 사용하여 공용수명을 예측하였으며, 예측 결과를 기반으로 각 포장의 생애주기 비용을 분석하였다. 본 연구의 목적은 혼합물의 성능평가를 통해 폴리머 개질 구스 아스팔 트 혼합물의 공용수명을 예측하고 생애주기 비용을 분석하는 것이다. 성능평가 시험결과 폴리머 개질 구스 아스팔트 혼합물이 TLA 구스, SMA 아스팔트 혼합물보다 반사균열, 피로균열 및 소성변형 저항성이 높은 것으로 나타났다. 포장설계 수명 예측 및 생애주기 비용분석결과 폴리머 개질 구스를 사용한 포장설계의 공용성이 가장 우수하며 가장 경제적인 것으로 나타났다.

국제사회는 1992년 유엔기후변화협약(UNFCCC), 1997년 교토의정서, 2015년 파리협정, 2018년 IPCC ‘1.5℃ 특별보고서’ 채택을 통하여 온실가스 감축 목표를 세워 기후 문제에 대응하고자 하였다. 이러한 흐름에 대한민국은 2020년 ‘2050 탄 소중립 선언 및 비전을 선포하였고, 2021년 탄소중립기본법을 제정하였다. 이중 도로 건설도 환경영향평가의 대상으로 설정하여 인프라 시설물의 탄소중립에 노력을 기울이고 있다. 하지만 2011년 국토교통부의 ‘시설물별 탄소배출량 산정 가이드라인’ 외 구체적인 생애주기 분석 방법이 부재한 상황이며 기수행된 연구에서는 전과정이 아닌 특정 수명주기에 집중하였던 단점이 존재하였다. 특히 수명주기 중 사용단계는 시설물 이용, 유지관리, 에너지 및 용수 사용 등의 내용을 포함하며 2023년 세계 경제 포럼은 사용단계의 탄소배출량이 평균적으로 전체 탄소배출량의 70%를 차지한다고 발표하였 기 때문에 사용단계의 탄소배출량을 산정하는 것은 중요하다. 따라서 본 연구에서는 국제 표준 ISO 21930:2017의 전과정 평가 LCA(Life Cycle Assessment) 방법과 국토교통부의 ‘시설물별 탄소배출량 산정 가이드라인’을 따라 국내 탄소배출 계수를 기반으로 도로건설 전과정의 생애주기 구분을 하였고, 탄소배출량을 산정하였다. 이를 통해 국내 환경영향평가 방법의 보완에 기여하고자 한다.

도로 주행 시 차량의 제동거리 확보와 곡선부 주행 안전성은 도로 설계에서 중요한 요소이며, 강우로 인해 형성되는 수 막은 타이어와 노면 간 마찰력을 저하시켜 제동거리를 증가시키고 주행 안전성을 저해하는 요인으로 작용한다. 기존 도 로 설계에서는 습윤 상태에서의 마찰계수를 기준으로 하지만, 측정 방식마다 수막두께 기준이 상이하여 적용에 한계가 있다. 본 연구에서는 RRL 및 Gallaway 수막두께 예측 모델을 활용하여 다양한 도로 및 기상 조건에서의 수막두께를 예 측하고, 실측 실험을 통해 신뢰도가 높은 모델을 선정한 후, Gallaway의 마찰계수 예측식을 적용하여 강우강도, 배수 거 리, 포장 경사, 노면 조직 깊이, 타이어 트레드 깊이에 따른 마찰계수 변화를 분석하였다. 연구 결과, 강우강도가 증가하 고 배수 거리가 길어질수록 수막두께가 증가하면서 마찰계수가 감소하는 경향을 보였으며, 반대로 포장 경사와 노면 조 직 깊이가 증가할 경우 배수 성능이 향상되어 수막두께가 얇아지고 마찰계수가 증가하는 것으로 나타났다. 이러한 마찰 계수 변화는 도로 안전성에 직접적인 영향을 미쳐, 강우가 심한 조건에서는 제동거리가 길어지고 곡선부에서는 더 큰 반 경이 필요해지는 것으로 분석되었다. 특히 설계속도가 높은 구간이나 수막두께가 깊이 형성되는 구간, 타이어 트레드 깊 이가 얕은 경우 현행 도로 설계 기준이 요구하는 정지 시거를 충족하지 못하는 사례가 발생하였으며, 곡선부에서도 동일 한 문제점이 확인되었다. 결과적으로 강우 조건을 반영한 도로 설계 기준의 보완이 필요하며, 배수 성능을 강화하고 마 찰력 저하를 방지할 수 있는 포장 기법을 적용하는 것이 요구된다. 또한, 강우 시 주행 안전성을 확보하기 위해 동적 속 도 제한 시스템 도입 및 유지관리 체계를 강화하고, 강우 조건을 고려한 정지 시거 및 곡선 반경 설계 기준을 마련함으 로써 도로 안전성을 향상시킬 필요가 있다.

국내 태양광 산업은 2000년대 초 크게 성장하였으나 태양광 패널의 수명이 도래함에 따라 폐패널 발생량이 급격히 증 가할 것으로 예상된다. 그러나 태양광 패널의 주요 구성요소인 강화유리는 상용화된 재활용 기술이 부족하여 대부분 파 쇄 후 매립되고 있는 실정이다. 향후 대량 발생하게 될 폐패널의 재활용 기술 개발 필요성이 대두됨에 따라 태양광 폐패 널의 강화유리를 아스팔트 콘크리트 재료로서 재활용할 수 있는 기술을 개발하고자 하였다. 따라서 폐패널 유리 골재를 제조 및 이를 적용한 아스팔트 혼합물의 배합설계를 수행하였으며 일반 아스팔트 혼합물과 폐패널 유리 골재 아스팔트 혼합물의 성능평가 및 경제성을 비교·분석하였다. 그 결과 폐패널 유리 아스팔트 혼합물이 저온균열 저항성을 제외한 모 든 성능 시험에서 우수한 성과를 보였으며, 경제성 또한 일반 아스팔트 혼합물과 비교 시 뛰어난 것으로 나타났다.

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 evaluates the applicability of mastic asphalt concrete for backfilling mini-trenches of communication cables. Characterization tests, such as the dynamic modulus, flow-number, Texas overlay, four-point bending beam, and Hamburg wheel tracking tests, were conducted on conventional mastic asphalt concrete and lower-temperature mastic asphalt concrete. A structural analysis of the backfilling of mini-trenches of mastic asphalt concrete was performed and compared with the results of conventional soil backfilling methods using the finite-element method. The performance year was calculated based on the strain behavior and the results of the structural analysis. A life-cycle cost analysis (LCCA) was performed based on net-present-value method. The results of laboratory experiments show that the lower-temperature mastic asphalt concrete performs better than conventional mastic asphalt concrete in terms of resistance to permanent deformation and fatigue cracking. The performance year of the mastic asphalt concrete is three times longer than that of the conventional sand-backfilling mini-trench. The LCCA results indicate that the cost of backfilling by the mastic asphalt concrete is two times lower than that by the conventional sand-backfilling mini-trench.

This paper presents a finite-difference method (FDM)-based heat-transfer model for predicting black-ice formation on asphalt pavements and establishes decision criteria using only meteorological data. Black ice is a major cause of winter road accidents and forms under specific surface temperature and moisture conditions; however, its accurate prediction remains challenging owing to dynamic environmental interactions. The FDM incorporates thermodynamic properties, initial pavement-temperature profiles, and surface heat-transfer mechanisms, i.e., radiation, convection, and conduction. Sensitivity analysis shows the necessity of a 28-d stabilization period for reliable winter predictions. Black-ice prediction logic evaluates the surface conditions, relative humidity, wind speed, and latent-heat accumulation to assess phase changes. Field data from Nonsancheon Bridge were used for validation, where a maximum prediction accuracy of 64% is indicated in specific cases despite the overestimation of surface temperatures compared with sensor measurements. These findings highlight the challenges posed by wet surface conditions and prolonged latent-heat retention, which extend the predicted freezing duration. This study provides a theoretically grounded methodology for predicting black ice on various road structures without necessitating additional measurements. Future studies shall focus on enhancing the model by integrating vehicle-induced heat effects, solar radiation, and improved weather-prediction data while comparing the FDM with machine-learning approaches for performance optimization. The results of this study offer a foundation for developing efficient road-safety measures during winter.

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.

To develop a heat-generating asphalt pavement utilizing a phase-change material (PCM), this study evaluated the application method of a PCM as an asphalt material and the thermal and physical properties of asphalt mixtures. The selection of PCM materials according to the phase-change temperature range suitable for thermal asphalt pavements and the encapsulation method for application to asphalt materials were examined, and encapsulated PCMs (ePCMs) using various materials were produced. The thermal and physical properties were evaluated through chamber experiments and strength tests by applying the ePCMs to asphalt mixtures. The characterization results of the ePCMs showed that ePCM-C had the highest latent heat, thermal stability, and physical stability in the asphalt binder and mixture. The chamber test results showed that ePCM-C, which had high latent heat, had the longest temperature delay time under all conditions. The mixing ratio was calculated by volume to substitute low-density ePCM into the mixture; as the ePCM content increased, the asphalt content also increased. The results of the Marshall stability and indirect tensile strength tests indicated that as the ePCM content increased, the strength and crack resistance properties decreased. Asphalt mixtures containing ePCMs have demonstrated the ability to maintain temperature for a long time within a specific temperature range. If an ePCM is improved such that it is not damaged under the production conditions of asphalt mixtures, it is expected to be sufficiently utilized as a technology for preventing road freezing.

This study aimed to manufacture emulsified asphalt for free-heated asphalt mixtures with high solid contents using the high internal phase ratio (HIPR) technique and utilize it as basic research data by evaluating the basic properties. The optimal emulsifier was selected by considering the physical and chemical properties of the emulsifier used in the emulsified asphalt, and the solid content in the emulsified asphalt was increased using the HIPR technique. Emulsified asphalt was produced with solid contents of 90%, 80%, 70%, and 62% (current standard) in emulsified asphalt, and the basic properties of the emulsified asphalt were evaluated for each content. In addition, a free-heated asphalt mixture for the surface layer was produced by applying the emulsified asphalt produced for each content, and the performance was evaluated based on the quality standard items presented in the current guidelines of the Ministry of Land, Infrastructure and Transport. When utilizing the HIPR technique, we could manufacture up to 90% of the asphalt solid content in the emulsified asphalt; however, applying it to unheated asphalt mixtures because of the increase in viscosity was impossible. We determined that it could be applied up to a maximum solid content of 80%. In addition, in the free-heated asphalt mixture test, the ratio of the air void increased as the solids content increased, but the strength decreased. An examination of the fracture surface after the strength test revealed that it was brown, which is a characteristic color of emulsified asphalt. This was because the curing time became insufficient as the solid content increased, resulting in insufficient time for strength development. To ensure the performance of the free-heated asphalt mixture, we observed that the viscosity of emulsified asphalt with a high solid content should be reduced; securing the curing time accordingly was an important factor, and it was determined that additional research is necessary.

This study aimed to develop a pavement management system suitable for the climate and traffic characteristics of Gangwon Province. This research focused on analyzing the asphalt pavement performance characteristics of national highways in Gangwon Province by region and developing prediction models for the current pavement performance and annual changes in performance. Quantitative indicators were collected to evaluate the condition of national highway pavements in Gangwon Province, including factors affecting road performance, such as weather data and traffic volume. The Gangwon region was then classified according to its topography, climate, weather, traffic volume, and pavement performance. Prediction models for the current pavement performance and annual changes in performance were developed for national highways. This study also compared the predicted values for the Gangwon region using a nationwide pavement performance-prediction model from other studies with the predicted values from the developed annual changes in the performance prediction model. This study established a foundation for implementing a pavement management system tailored to the unique climate and traffic characteristics of Gangwon Province. By developing region-specific performance prediction models, this study provided valuable insights into more effective and efficient pavement maintenance strategies in Gangwon Province.

In this study, a performance evaluation was conducted on a composite elastic asphalt precast expansion joint developed to replace steel expansion joints that frequently suffer from various damages, such as blow-up owing to increased traffic volume and abnormal weather. Two types of elastic asphalt binders were prepared by mixing a latex-based modifier, and their basic properties and performance were evaluated. Elastic asphalt binders were mixed with 8–13 and 13–19 mm aggregates to prepare elastic asphalt joint mixtures, and their permanent deformation and adhesive performance were evaluated using Hamburg wheel-tracking and direct-shear tests. Elastic asphalt joint blocks and internal reinforcement for crack prevention were applied to produce the elastic composite expansion joints, and their performance was evaluated through contraction–extension tests to determine fatigue cracking, maximum load during contraction– extension, and repeated contraction–extension tests. As a result of the performance evaluation of the developed elastic asphalt binder, both the high- and low-temperature performances were improved, and the temperature sensitivity was superior to that of general asphalt binders, exhibiting high resistance to cracking. In addition, the joint block specimens manufactured by mixing the elastic asphalt binder with 13–19 mm aggregates exhibited excellent permanent deformation in the dynamic stability and Hamburg wheel-tracking tests, and they had higher adhesive performance than the method of repairing with rapid-hardening concrete materials at low and room temperatures, where significant contraction of the concrete joint occurs. We confirmed that when a compression spring-type reinforcement was applied, the compressive force for contraction decreased significantly compared with the unreinforced state, and the tensile force for extension increased, thereby reducing the stress applied to the mixture itself. The composite elastic asphalt precast expansion joint developed in this study is expected to have superior durability against cracks and secure continuity with the road surface through the tensile force dispersing effect using expansion reinforcement. Thus, it has better drivability than the existing steel expansion joint and can absorb shocks such as vibrations and noise applied to a structure.

The purpose of this study was to optimize the design of asphalt concrete pavements for Jeju Island by considering the regional characteristics of the island. This study employed an MEPDG program to determine the allowable traffic loads for class 4 vehicles by considering the axle loads, climate, and material properties. Samples of basalt asphalt concrete from Jeju were used to measure the dynamic modulus for material property estimation. The climate input was based on 30-year climate data from Jeju. The thicknesses and moduli of the subgrade, subbase, and asphalt layers were incorporated into the design. The regression-analysis program SPSS was used to develop a regression equation for the overlay design, factoring in the modulus and thickness ratios between the existing and overlay asphalt layers. A pavement-thickness design formula tailored to Jeju's characteristics was derived. An equivalent single-axle load factor (ESALF) formula was developed to facilitate traffic-load estimation for different roads, enabling the easy incorporation of varying traffic volumes into the design. The ESALF formula demonstrated a high correlation with the pavement thickness, subgrade conditions, and axle loads, whereas the pavementthickness design formula exhibited strong correlations with the pavement thickness, subgrade state, thickness ratios, and modulus ratios. The use of basalt aggregates in asphalt concrete pavements provides an economically viable and technically sound solution for Jeju. The proposed design methodology not only reduces costs but also enhances pavement performance and road safety. The developed formulas offer flexibility in adjusting designs based on specific traffic conditions, providing optimal pavement solutions for different road categories.

This study aimed to improve the accuracy of road pavement design by comparing and analyzing various statistical and machine-learning techniques for predicting asphalt layer thickness, focusing on regional roads in Pakistan. The explanatory variables selected for this study included the annual average daily traffic (AADT), subbase thickness, and subgrade California bearing ratio (CBR) values from six cities in Pakistan. The statistical prediction models used were multiple linear regression (MLR), support vector regression (SVR), random forest, and XGBoost. The performance of each model was evaluated using the mean absolute percentage error (MAPE) and root-mean-square error (RMSE). The analysis results indicated that the AADT was the most influential variable affecting the asphalt layer thickness. Among the models, the MLR demonstrated the best predictive performance. While XGBoost had a relatively strong performance among the machine-learning techniques, the traditional statistical model, MLR, still outperformed it in certain regions. This study emphasized the need for customized pavement designs that reflect the traffic and environmental conditions specific to regional roads in Pakistan. This finding suggests that future research should incorporate additional variables and data for a more in-depth analysis.

This study aimed to evaluate the performance criteria of low-noise asphalt pavements under laboratory conditions. Laboratory tests were performed on eight porous and three non-porous asphalt mixtures. Draindown, Cantabro, tensile strength ratio (TSR), and dynamic stability tests were conducted to evaluate durability. The functionality was assessed using sound-absorption and indoorpermeability- coefficient tests. The laboratory results showed that all mixtures satisfied the quality standards for the draindown and TSR tests. In the dynamic stability test, all the mixtures demonstrated adequate rutting resistance. For porous mixtures, the Cantabro test results indicated sufficient shatter resistance and the indoor-permeability-coefficient test confirmed proper drainage performance. All mixtures exhibited satisfactory sound absorption, with the porous mixtures exhibiting slightly better sound absorption than the non-porous mixtures. Both porous and non-porous mixtures are durable and functional and are used in Korea. Future field tests are required to evaluate the noise reduction performance under different conditions and to compare the in-situ performance results with those from laboratory tests.

This study determined the minimum size of a representative molecular structure for use in future dynamic analyses of asphalt binders. The minimum representative size, considering factors such as aging, additive types, and temperature variations, was established using density and radial distribution functions. This approach ensures that the structure reflects temperature-dependent property changes, which are critical characteristics of asphalt binders. In this study, the structure of asphalt-binder molecules was generated using the composition proposed by Li and Greenfield (2014) for AAA1. To assess the appropriateness of the molecular structure size, we generated additional structures, X2 and X3, maintaining the same composition as X1, but with two and three times the number of molecules, respectively, as suggested by Li and Greenfield (2014). Silica and lignin were considered as additives, and the aging conditions examined included unaged, short-term aging, and long-term aging. In addition, 11 temperature conditions were investigated. The density and radial distribution functions were plotted and analyzed. The variables influencing the density and radial distribution functions were set as the aging degree of the asphalt binder (unaged, short-term aging, long-term aging), 11 temperature conditions ranging from 233 to 433 K in 20 K intervals, structure size (X1, X2, and X3), and the presence of additives (no additives, silica, and lignin). For density, clear differences were observed based on the degree of aging, temperature conditions, and presence of additives, whereas the structure size did not significantly affect the density. In terms of radial distribution functions, the X1 structure reflected differences based on the degree of aging and the presence of additives but was limited in exhibiting temperature-dependent variations. In contrast, the X3 structure effectively captured temperature-dependent trends, indicating that the size of the molecular structure is crucial when evaluating energy calculations or physical tensile strength, necessitating careful assessment.

Effective mixing of different-sized aggregates in mobile asphalt plant dryers is crucial for ensuring high-quality, consistent asphalt production. This study explores the application of spatial analysis techniques, particularly the Discrete Element Method (DEM), to understand and optimize the mixing process of aggregates in drum dryers. The research emphasizes the importance of proper mixing to achieve uniform moisture removal and heating across various aggregate sizes. Larger aggregates heat more slowly, while finer particles risk overheating or being carried away by air currents, necessitating careful management of the mixing process. Using LIGGGHTS, an open-source simulation framework, we conducted DEM simulations to analyze the spatial distribution and behavior of aggregates within a 3D model of a drum dryer. The study considered multiple factors affecting mixing efficiency, including drum inclination, rotational speed, and aggregate feeding frequency. Results indicate that the rotational speed of the drum dryer has the most significant impact on mixing effectiveness. The DEM simulations provided valuable insights into particle movement, heat transfer, and potential segregation issues within the dryer. Further investigations into additional factors that may influence aggregate mixing in drum dryers is recommended, paving the way for improved efficiency and quality in asphalt manufacturing.