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Title: How Microstructure and Pore Moisture Affect Strength Gain in Portlandite-Enriched Composites That Mineralize CO2

Journal Article · · ACS Sustainable Chemistry & Engineering

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 portlanditeenriched 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. Furthermore, these insights are foundational to create new “low-CO2” cementation agents via in situ CO2 mineralization (utilization) using dilute CO2 waste streams.

Research Organization:
Univ. of California, Los Angeles, CA (United States)
Sponsoring Organization:
USDOE Office of Fossil Energy (FE)
Grant/Contract Number:
FE0029825; FE0031718
OSTI ID:
1915659
Journal Information:
ACS Sustainable Chemistry & Engineering, Vol. 7, Issue 15; ISSN 2168-0485
Publisher:
American Chemical Society (ACS)Copyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 35 works
Citation information provided by
Web of Science

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