How microstructure and pore moisture affect strength gain in portlandite-enriched composites that mineralize CO2

Iman Mehdipour, Gabriel Falzone, Erika Callagon La Plante, Dante Simonetti, Narayanan Neithalath, Gaurav Sant

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

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.

Original languageEnglish (US)
Pages (from-to)13053-13061
Number of pages9
JournalACS Sustainable Chemistry and Engineering
Volume7
Issue number15
DOIs
StatePublished - Aug 5 2019

Keywords

  • CO utilization
  • Carbonation
  • Cementation
  • Microstructure
  • Transport

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry
  • Chemical Engineering(all)
  • Renewable Energy, Sustainability and the Environment

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