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 - 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 -