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Title: Examining Carbonation of Calcium Silicate-Based Cements in Real Time Using Neutron Radiography

Author(s): Rita Maria Ghantous, Margaret N. Goodwin, Mehdi Khanzadeh Moradllo, Sean Quinn, Vahit Aktan, O. Burkan Isgor, Steven Reese, and W. Jason Weiss

Publication: Materials Journal

Volume: 120

Issue: 6

Appears on pages(s): 47-60

Keywords: calcium silicate cements; carbonation; diffusion coefficients; drying; neutron radiography

DOI: 10.14359/51739146

Date: 12/1/2023

Carbonatable calcium silicate cement (CSC) is a promising approach to reducing the carbon footprint associated with concrete production. Carbonatable CSC gains strength by reacting with carbon dioxide (CO2). While the concept of carbonation is well known, more information on the curing process is needed. This study focuses on studying the impact of drying time, carbonation duration, and degree of saturation (DOS) on the carbonation reaction of CSC mortar. Samples were exposed to different drying durations at controlled environmental conditions to reach various DOSs ranging from 100 to 0%. The samples were then exposed to carbonation under the same environmental conditions for different durations. Neutron radiography (NR) was performed on the samples during drying to determine the DOS corresponding to various drying durations. NR was also used during the carbonation period to determine the degree of carbonation (DOC) in real time. The impact of carbonation on the diffusivity of water vapor (Dh) and pore size distribution of CSC-based samples was examined using dynamic vapor sorption (DVS). It was concluded that the carbonation reaction increased as the DOS decreased from 100 to 40%. The carbonation reaction ceased for samples with DOS values less than 6% DOS. It was also concluded that as the DOC increased, the pore structure was refined, which led to a decrease in the Dh of the CSC mortar samples.