This study aims to improve laboratory aging procedures for bituminous materials to better replicate field conditions. Two binders and mixtures were subjected to various levels of humidity, temperatures, pressures, film thicknesses, and aging durations. By comparing these lab-aged samples to field-aged samples, the study aims to simulate real-world aging more accurately. Fourier-transform infrared (FTIR) spectroscopy and frequency sweep tests were employed to analyse these samples. Multivariate techniques—Principal Component Analysis (PCA), Multiple Linear Regression (MLR), and Support Vector Regression (SVR)—were used to explore chemical and rheological relationships, evaluate the interchangeability of aging factors, and quantify the equivalency between laboratory and field aging. The findings revealed that increased temperature, pressure, and duration lead to more oxidative products. The PCA distinguished between two binders and aging trends, highlighting the importance of both FTIR and rheological measurements. The SVR model demonstrated strong predictive performance for rheological properties, identifying critical FTIR region, 710–912 -1cm. By MLR model, optimal aging conditions to simulate nine years of field aging for porous asphalt and stone mastic asphalt were back-calculated. The Euclidean distance found laboratory conditions that closely match field-aged samples. SVR models provided predictions of simulated field aging time for various laboratory aging conditions.@en

When oxygen diffuses in a bituminous film, it also reacts, simultaneously, with the constituents of the bitumen and as such it is gradually depleted. This depletion process masks the characteristics of the actual diffusion process and complicates the determination of the diffusion coefficient needed for computation of oxygen concentration and its effects on bitumen degradation due to aging. In the present study, experiments were carried out to measure objectively oxygen absorption in bitumen at various temperatures independently of oxygen depletion phenomena. To achieve this, an improved version of van Oort’s test set up was utilized and oxygen was replaced by nitrogen. A Laplace transform based numerical technique was developed for processing the test results to determine the diffusion coefficients under various conditions. Once validated, they were used in finite element simulations to demonstrate the influence of time and temperature on gas diffusion and concentration in porous asphalt mixtures.@en