Clinkering-Free Cementation by Fly Ash Carbonation

Author

Zhenhua Wei
Bu Wang
Gabriel Falzone
Erika Callagon La Plante
Monday Uchenna Okoronkwo, Missouri University of Science and TechnologyFollow
Zhenyu She
Tandre Oey
Magdalena Balonis
Narayanan Neithalath
Laurent Pilon
Gaurav Sant

Abstract

The production of ordinary portland cement (OPC) is a CO₂ intensive process. Specifically, OPC clinkering reactions not only require substantial energy in the form of heat, but they also result in the release of CO₂; i.e., from both the decarbonation of limestone and the combustion of fuel to provide heat. To create alternatives to this CO₂ intensive process, this paper demonstrates a new route for clinkering-free cementation by the carbonation of fly ash; i.e., a by-product of coal combustion. It is shown that in moist environments and at sub-boiling temperatures, Ca-rich fly ashes react readily with gas-phase CO₂ to produce robustly cemented solids. After seven days of exposure to vapor-phase CO₂ at 75 °C, such formulations achieve a compressive strength of around 35 MPa and take-up 9% CO₂ (i.e., by mass of fly ash solids). On the other hand, Ca-poor fly ashes due to their reduced alkalinity (i.e., low abundance of mobile Ca- or Mg-species), show limited potential for CO₂ uptake and strength gain -- although this deficiency can be somewhat addressed by the provision of supplemental/extrinsic Ca agents. The roles of CO₂ concentration and processing temperature are discussed, and linked to the progress of reactions and the development of microstructure. The outcomes create new pathways for achieving clinkering-free cementation while enabling the beneficial utilization ("upcycling") of emitted CO₂ and fly ash; i.e., two abundant, but underutilized industrial by-products.

Recommended Citation

Z. Wei and B. Wang and G. Falzone and E. C. La Plante and M. U. Okoronkwo and Z. She and T. Oey and M. Balonis and N. Neithalath and L. Pilon and G. Sant, "Clinkering-Free Cementation by Fly Ash Carbonation," Journal of Co2 Utilization, vol. 23, pp. 117 - 127, Elsevier Ltd, Jan 2018.

The definitive version is available at https://doi.org/10.1016/j.jcou.2017.11.005

Department(s)

Chemical and Biochemical Engineering

Keywords and Phrases

Cementation; CO2; Concrete; Fly ash; Strength; Upcycling

International Standard Serial Number (ISSN)

2212-9820

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2018 Elsevier Ltd, All rights reserved.

Publication Date

01 Jan 2018