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.

ABSTRACT
1. 연구배경 및 목적
    1.1. 연구배경
    1.2. 연구 목적
2. 연구방법
    2.1. 분자동역학 활용 계산 방법
3. 결과 분석
    3.1. 밀도
    3.2. 방사형밀도
4. 요약 및 결론
REFERENCES

• 윤태영(한국건설기술연구원 도로교통연구본부 연구위원) | Yun Taeyoung (Research Fellow Department of Highway & Trasnporation Research, Korea Institute of Civil Engineering and Building Technology, 283, Goyangdae-Ro, Ilsanseo-Gu, Goyang-Si, Gyeonggi-Do 10223, Korea) Corresponding author