The effect of slag chemistry on CO&lt;sub&gt;2&lt;/sub&gt; binding capacity of C&lt;sub&gt;3&lt;/sub&gt;S-slag (-gypsum) system

Zhang, Y.; Copuroglu, Oguzhan

doi:10.1016/j.conbuildmat.2022.129208

The effect of slag chemistry on CO₂ binding capacity of C₃S-slag (-gypsum) system

Title

The effect of slag chemistry on CO₂ binding capacity of C₃S-slag (-gypsum) system

Author

Zhang, Y. (TU Delft Materials and Environment)
Copuroglu, Oguzhan (TU Delft Materials and Environment)

Date

2022

Abstract

In this paper, the authors investigated the correlation between slag chemistry and CO₂ binding capacity of the blended system. To simplify the composition of mixture, model paste containing C₃S, slag covering the common composition range and gypsum was employed. After accelerated carbonation test, three CO₂-binding phases were identified in the system as: carbonated Ca-Al AFm phases, carbonated hydrotalcite-like phase, and calcium carbonate, irrespective of slag chemistry and the addition of gypsum. On the other hand, carbonated Ca-Al AFm phases played a minor role in absorbing CO₂, sharing less than 5% of CO₂ among all carbonate phases. Hydrotalcite-like phase was able to bind up to ∼10% CO₂, depending on the Mg/Al atomic ratio of raw slag. CaCO₃, originated from the carbonation of portlandite and C−S−H gel phase, took up more than 85% CO₂ after carbonation. Moreover, the carbonation degree of C−S−H gel phase was found to be negatively related with the Al₂O₃ content and Ca/Si ratio of raw slag.