TY - JOUR
T1 - Clinkering-free cementation by fly ash carbonation
AU - Wei, Zhenhua
AU - Wang, Bu
AU - Falzone, Gabriel
AU - La Plante, Erika Callagon
AU - Okoronkwo, Monday Uchenna
AU - She, Zhenyu
AU - Oey, Tandre
AU - Balonis, Magdalena
AU - Neithalath, Narayanan
AU - Pilon, Laurent
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 ), Anthony and Jeanne Pritzker Foundation , and the National Science Foundation (CAREER Award: 1235269 ). This research was conducted in the Laboratory for the Chemistry of Construction Materials (LC 2 ), Molecular Instrumentation Center (MIC), and the Electron Microscopy Core Facility at UCLA. 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.
Publisher Copyright:
© 2017 Elsevier Ltd
PY - 2018/1
Y1 - 2018/1
N2 - 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.
AB - 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.
KW - CO
KW - Cementation
KW - Concrete
KW - Fly ash
KW - Strength
KW - Upcycling
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U2 - 10.1016/j.jcou.2017.11.005
DO - 10.1016/j.jcou.2017.11.005
M3 - Article
AN - SCOPUS:85035757801
SN - 2212-9820
VL - 23
SP - 117
EP - 127
JO - Journal of CO2 Utilization
JF - Journal of CO2 Utilization
ER -