Evaluation of the CO2 capture and storage capacities of building materials

This work aims to explore the process of CO2 solubilization/adsorption in bitumen and bituminous materials. This process has been extensively characterized in scientific literature under relatively high-pressure conditions (20-100 bar). The purpose of this work is to study the phenomenon at ambient or low pressure, to determine the process kinetics, the CO2 storage stability, and the maximum CO2 capacity of the investigated materials: an asphalt aggregates sample and two bitumen formulations, one of which modified with additives incorporation. The work is developed in three steps. In the first step the bitumen-CO2 system is characterized at ambient pressure; in the second step the system is investigated in the 1-20 bars pressure range; in the final part of the work the bitumen formulations are subjected to temperatures up to 160 ºC and the released volatile components are characterized by Gas Phase Chromatography. The results obtained in the first two phases of the work show that the amount of solubilized CO2 in bitumen grows linearly with pressure. The modified bitumen can solubilize grater CO2 quantities compared to the additives-free bitumen. The asphalt aggregates adsorb negligeable amounts. After more than 9 days of free-air exposition, the carbonated bitumen formulations retain considerable CO2 mass fractions: 0.05% - 0.07% for unmodified bitumen and around 0.5% for modified bitumen. The asphalt aggregates lose all the adsorbed CO2 in less than 20 hours. The Gas Phase Chromatography analysis shows that heating the bitumen up to 160°C leads to the release of C8-C20 alkanes. No substantial differences in the released components are observed between the two bitumen formulations. The property of modified bitumen to solubilize larger CO2 quantities than classic bitumen, and capacity to store significant CO2 amounts for relatively large times periods, makes this material an interesting candidate for the CO2 sequestration and stockage technologies and paves the way for new studies to characterize the chemical-physical interactions underlying the bitumen-additives-CO2 system.