Experimental and computational investigation of gas diffusion in bitumen
R. Jing (TU Delft - Pavement Engineering)
Diederik van Lent (TNO)
Cor Kasbergen (TU Delft - Pavement Engineering)
A. Skarpas (TU Delft - Pavement Engineering)
Xueyan Liu (TU Delft - Pavement Engineering)
Sandra Erkens (TU Delft - Pavement Engineering)
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Abstract
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.