4.1 Article

Classification and Milling Increase Fly Ash Pozzolanic Reactivity

Journal

FRONTIERS IN BUILT ENVIRONMENT
Volume 7, Issue -, Pages -

Publisher

FRONTIERS MEDIA SA
DOI: 10.3389/fbuil.2021.670996

Keywords

fly ash; cement; reactivity; supplementary cementitious material; classification; milling; upcycling; reclaimed

Funding

  1. European Institute of Innovation and Technology (EIT) Raw Materials [PA 16390]

Ask authors/readers for more resources

Upcycling and reclaiming low-quality or stored coal combustion fly ashes can provide a large resource of supplementary cementitious materials for low-carbon blended cements. This study compared the impact of size classification and milling treatments on the reactivity of a siliceous fly ash, showing significant increases in reactivity with fine classified and milled fly ash. Increasing the inherent reactivity of fly ashes was found to be an effective way to improve strength development in blended cements.
Upcycling and reclaiming of low quality or stored coal combustion fly ashes could enable to tap into a voluminous resource of supplementary cementitious materials (SCMs) for low-carbon blended cements. Low reactivity fly ashes are usually either too crystalline or too coarse. Beneficiation treatments for coarse fly ashes comprise size classification or milling processes to extract or produce fine size fractions of higher pozzolanic reactivity. This article compares the effect of size classification and milling treatments on the reactivity of a siliceous fly ash (FA). The intrinsic chemical reactivity is assessed using the R3 heat release test method. The results showed significant increases of 57 and 40% for fine classified and milled fly ash compared to the initial fly ash, respectively. In addition heat release and portlandite consumption were measured for blended cements with 30 wt.% Portland cement replacement by the fly ashes. Both test results are combined to calculate the degree of reaction of the fly ashes over time in blended cement. The results demonstrate a strong effect of particle size on fly ash reactivity and degree of reaction. It is shown that increasing the inherent reactivity of fly ashes is an effective way of both accelerating compressive strength gain and enhancing late age strength with fine classified fly ashes reaching equivalent strength as neat Portland cement by 28 days and attaining a strength activity index of 137% by 90 days.

Authors

I am an author on this paper
Click your name to claim this paper and add it to your profile.

Reviews

Primary Rating

4.1
Not enough ratings

Secondary Ratings

Novelty
-
Significance
-
Scientific rigor
-
Rate this paper

Recommended

No Data Available
No Data Available