Advancements in ultraviolet (UV) spectroscopy and spectroscopy ellipsometry (SE) for asphalt binder characterization: a State-of-the-Art review

Abstract The longevity and performance of asphalt pavements are heavily influenced by the physicochemical properties of asphalt binders, which degrade over time due to environmental and mechanical stressors such as ultraviolet (UV) radiation, oxidative aging, and traffic-induced loading. Traditional binder characterization methods rely primarily on rheological or empirical approaches, often lacking the resolution to capture molecular-level transformations. This review presents a comprehensive synthesis of recent advancements in ultraviolet (UV) spectroscopy and spectroscopic ellipsometry (SE) as emerging tools for asphalt binder analysis. UV spectroscopy enables sensitive detection of oxidation and photo-degradation products through absorption profiling of chromophoric functional groups, while ellipsometry offers nanometric precision in quantifying optical constants and surface film evolution. Despite their promise, existing studies remain fragmented, with major gaps in (i) linking laboratory-scale UV/SE measurements to field performance, and (ii) establishing standardized protocols for sample preparation and optical data interpretation. Addressing these challenges is critical for ensuring reproducibility and for translating spectroscopic insights into practical engineering specifications. The integration of these techniques with machine learning, imaging modalities, and remote sensing platforms has demonstrated significant potential in predicting binder aging behavior, performance deterioration, and modification efficacy. Novel applications in nanotechnology, spatial mapping, and in-situ monitoring are discussed, alongside the development of standardized calibration frameworks to ensure measurement comparability. Through critical evaluation of structure–property relationships and data-fusion strategies, this review establishes a roadmap for incorporating UV and ellipsometric techniques into mainstream asphalt research and practice. The insights presented support the development of durable, sustainable pavement systems tailored to meet evolving performance specifications and climatic demands.