Reaction of hydrated cement paste with supercritical carbon dioxide

For geologic sequestration of captured CO2, CO2 is stored in spent oil wells and concrete is used to seal wellbore penetrations to prevent leakage of CO2. In such deep underground environment, CO2 stays in supercritical condition, so carbonation resistance of portland cement concrete against supercritical CO2 becomes critical for ensuring long-term durability of wellbore concrete. In this work, reaction between hydrated portland cement and supercritical CO2 was investigated at different temperature and pressure levels. It is to provide necessary information on prediction of long-term performance of portland cement concrete in wellbore environment. According to the experimental results, it was found that the amount of aragonite increased with the increase in temperature and pressure, but vice versa for the case of vaterite. In terms of total CO2 uptake into hydrated cement paste, there was no clear relation observed as increase in temperature and pressure. It is probably due to the fact that hydrated cement paste has reached its full level of carbonation after 24 h of reaction with supercritical CO2. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

This study investigated the reaction between hydrated portland cement and supercritical CO2 at different temperature and pressure levels to understand the long-term durability prediction of concrete in wellbore environment. Experimental results showed an increase in aragonite amount with higher temperature and pressure, while the opposite was observed for vaterite. There was no clear relation observed in total CO2 uptake into hydrated cement paste with increasing temperature and pressure, possibly due to saturation of carbonation after 24 hours of reaction.