TY - JOUR
T1 - How microstructure and pore moisture affect strength gain in portlandite-enriched composites that mineralize CO2
AU - Mehdipour, Iman
AU - Falzone, Gabriel
AU - La Plante, Erika Callagon
AU - Simonetti, Dante
AU - Neithalath, Narayanan
AU - Sant, Gaurav
N1 - Funding Information:
The authors acknowledge financial support for this research from the Department of Energy: Office of Fossil Energy via the National Energy Technology Laboratory (NETL; DE-FE0029825 and DE-FE0031718), The Anthony and Jeanne Pritzker Family Foundation, and the National Science Foundation (CAREER Award: 1253269). This research was conducted in the Laboratory for the Chemistry of Construction Materials (LC 2 ). As such, the authors gratefully acknowledge the support that has made these laboratories and their operations possible. The contents of this paper reflect the views and opinions of the authors, who are responsible for the accuracy of the datasets presented herein, and do not reflect the views and/or policies of the funding agencies, nor do the contents constitute a specification, standard or regulation. The authors acknowledge Alex Hall (Suffolk Construction), James McDermott (Rusheen Capital Management/U.S. Renewables Group), and Edward Muller (Transocean/AeroVironment) for many stimulating discussions and for their insights over the course of this research.
Publisher Copyright:
© 2019 American Chemical Society.
PY - 2019/8/5
Y1 - 2019/8/5
N2 - Binders containing portlandite (Ca(OH)2) can take up carbon dioxide (CO2) from dilute flue gas streams (<15% CO2, v/v), thereby forming carbonate compounds with binding attributes. While the carbonation of portlandite particulates is straightforward, it remains unclear how CO2 transport into monoliths is affected by microstructure and pore moisture content. Therefore, this study elucidates the influences of pore saturation and CO2 diffusivity on the carbonation kinetics and strength evolution of portlandite-enriched composites ("mortars"). To assess the influences of microstructure, composites hydrated to different extents and conditioned to different pore saturation levels (Sw) were exposed to dilute CO2. First, reducing saturation increases the gas diffusivity and carbonation kinetics so long as saturation exceeds a critical value (Sw,c ≈ 0.10) independent of microstructural attributes. Second, careful analysis reveals that both traditional cement hydration and carbonation offer similar levels of strengthening, the magnitude of which can be estimated from the extent of each reaction. As a result, portlandite-enriched binders offer cementation performance that is similar to traditional materials while offering an embodied CO2 footprint that is more than 50 % smaller. These insights are foundational to create new "low-CO2" cementation agents via in situ CO2 mineralization (utilization) using dilute CO2 waste streams.
AB - Binders containing portlandite (Ca(OH)2) can take up carbon dioxide (CO2) from dilute flue gas streams (<15% CO2, v/v), thereby forming carbonate compounds with binding attributes. While the carbonation of portlandite particulates is straightforward, it remains unclear how CO2 transport into monoliths is affected by microstructure and pore moisture content. Therefore, this study elucidates the influences of pore saturation and CO2 diffusivity on the carbonation kinetics and strength evolution of portlandite-enriched composites ("mortars"). To assess the influences of microstructure, composites hydrated to different extents and conditioned to different pore saturation levels (Sw) were exposed to dilute CO2. First, reducing saturation increases the gas diffusivity and carbonation kinetics so long as saturation exceeds a critical value (Sw,c ≈ 0.10) independent of microstructural attributes. Second, careful analysis reveals that both traditional cement hydration and carbonation offer similar levels of strengthening, the magnitude of which can be estimated from the extent of each reaction. As a result, portlandite-enriched binders offer cementation performance that is similar to traditional materials while offering an embodied CO2 footprint that is more than 50 % smaller. These insights are foundational to create new "low-CO2" cementation agents via in situ CO2 mineralization (utilization) using dilute CO2 waste streams.
KW - CO utilization
KW - Carbonation
KW - Cementation
KW - Microstructure
KW - Transport
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U2 - 10.1021/acssuschemeng.9b02163
DO - 10.1021/acssuschemeng.9b02163
M3 - Article
AN - SCOPUS:85070924151
SN - 2168-0485
VL - 7
SP - 13053
EP - 13061
JO - ACS Sustainable Chemistry and Engineering
JF - ACS Sustainable Chemistry and Engineering
IS - 15
ER -