Thermal properties and chemical composition of bituminous materials exposed to accelerated ageing

Three aged and unaged asphalts and their corresponding asphaltenes and maltenes were characterised by means of thermal analysis and fractionation. Rolling thin film oven test and pressure ageing vessel procedures were followed to simulate thermo-oxidative ageing conditions. The temperatures associated with the glass transition region of aged and unaged samples were determined by modulated differential scanning calorimetry (MDSC), and the temperatures related to the thermal degradation process were determined by thermogravimetry (TG). Fractional composition of asphalts was determined by Corbett's fractionation procedure. It was found that the temperatures related to the glass transition region are higher for aged asphalts, while thermal degradation shows similar patterns between the studied samples. Fractional composition had an evolution with ageing. The results show that thermal analysis can be used to identify the type of asphalt being studied; MDSC can be used to identify the ageing degree of an asphalt, based on the changes of glass transition properties, unlike the results obtained with TG and DTG (derivative thermogravimetric) analysis.