Effect of temperature on carbon dioxide mineralisation in recycled cement paste

In this work, an approach towards a carbon-neutral cement industry using carbon dioxide mineralisation of recycled concrete paste is investigated. It focuses on the effect of temperature on the enforced carbonation of cement paste. The enforced carbonation is a rapid process at ambient temperature, which is further accelerated at elevated temperatures. Moreover, the extent of the reaction is increased when the temperature rises. The carbonation reaction is divided into two kinetic stages. During the first stage, the carbonation kinetics is controlled by the availability of carbon dioxide that increases at higher temperatures. During the second stage, the reaction kinetics is controlled by the dissolution of the hydrates. Increased temperature accelerates this process by increasing the undersaturation level of the dissolving phases. The main carbonation products are calcium carbonate and an alumina-silica gel. The increasing temperature has a limited impact on these phases, and the differences come mainly from the different degrees of carbonation.

Automated summary

This research investigates the carbon-neutralization of the cement industry by using carbon dioxide mineralization of recycled concrete paste. The focus is on the impact of temperature on the enforced carbonation process of cement paste. The results show that enforced carbonation is a rapid process at ambient temperature, but it is further accelerated at elevated temperatures. The reaction extent is also increased with higher temperatures. The carbonation reaction consists of two kinetic stages, with the availability of carbon dioxide controlling the kinetics in the first stage and the dissolution of hydrates controlling it in the second stage. Increased temperature enhances this process by increasing the undersaturation level of the dissolving phases. The main carbonation products are calcium carbonate and alumina-silica gel.