Characterization of moisture vapor diffusion in fine aggregate mixtures using Fickian and non-Fickian models

Publication date: 15 June 2017
Source:Materials & Design, Volume 124
Author(s): Huining Xu, Jing Zhou, Qifeng Dong, Yiqiu Tan
Moisture vapor diffusion resulting from the difference in relative humidity between air and pavement material contributes to moisture damage. Understanding moisture vapor diffusion in asphalt pavement is the first task in the analysis of moisture damage. Analysis was conducted in an automated environmental chamber with a temperature precision of ±0.5°C and relative humidity precision of ±3%. Moisture uptake profiles for fine aggregate mixtures (FAMs) under various environmental conditions (relative humidity and ambient air temperature) and constituent materials (aggregate and asphalt binder) were measured. Preliminary data analysis showed the existence of Non-Fickian diffusion behavior. Therefore, two non-Fickian and one Fickian models were introduced to fit the measured moisture uptake data and determine FAM diffusion characteristics, such as diffusion coefficient, diffused moisture phase, and time-variable diffusion. Based on the variation in FAM diffusion characteristics under various experimental conditions and constituent material combinations, sensitivity analysis was conducted with one-way ANOVA and the determinants of FAM vapor diffusion characteristics were proposed.

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