Flue gas desulfurization (FGD) fly ash as a sustainable, safe alternative for cement-based materials

The reduction in fly ash production in coal-fired power plants has created an opportunity to explore alternative types of fly ashes previously deemed unfit for use in concrete. In plants using flue gas desulfurization (FGD) processes, fly ash could contain high amounts of sulfur oxides, making its u...

Full description

Saved in:
Bibliographic Details
Published in:Journal of cleaner production 2021-02, Vol.283 (C), p.124646, Article 124646
Main Authors: Navarrete, Ivan, Vargas, Felipe, Martinez, Patricia, Paul, Alvaro, Lopez, Mauricio
Format: Article
Language:English
Subjects:
Concrete
Durability
Ettringite
Gypsum
Hannebachite
Internal sulfate attack
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The reduction in fly ash production in coal-fired power plants has created an opportunity to explore alternative types of fly ashes previously deemed unfit for use in concrete. In plants using flue gas desulfurization (FGD) processes, fly ash could contain high amounts of sulfur oxides, making its use in concrete inadvisable. However, the type of sulfur compound present in a fly ash strongly impacts its performance in concrete. In this study, two types of fly ash were used to evaluate the effect of sulfur oxides on mortar mixtures incorporating fly ash as supplementary cementitious material (SCM); one from an FGD unit, with high sulfur oxide content (in the form of hannebachite), and the other generated in a system without FGD, with negligible sulfur oxide. Calorimetry results show that hannebachite can effectively control C3A hydration similar to gypsum; however, its presence in FGD fly ash does not induce deleterious expansion associated with internal sulfate attack in mortars. TGA and XRD analyses suggest that hannebachite has lower reactivity than sulfate. Hannebachite not only maintains the pozzolanic reactivity of the fly ash, but its fineness may promote OPC hydration, increasing compressive strength. The results of this study indicate that FGD fly ash can be used as an SCM, allowing more sustainable concrete production. -Hannebachite in FGD fly ash has lower reactivity than gypsum-Sulfur oxides in FGD FA can act as a setting regulator, without deleterious expansion-Reuse of FGD FA yields similar performance and environmental impact to conventional FA-The use of FGD FA in concrete can allow for a more sustainable concrete production
ISSN:0959-6526
1879-1786
DOI:10.1016/j.jclepro.2020.124646