AUTHOR=Snellings Ruben , Kazemi-Kamyab Hadi , Nielsen Peter , Van den Abeele Liesbet 

TITLE=Classification and Milling Increase Fly Ash Pozzolanic Reactivity

JOURNAL=Frontiers in Built Environment

VOLUME=Volume 7 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/built-environment/articles/10.3389/fbuil.2021.670996

DOI=10.3389/fbuil.2021.670996

ISSN=2297-3362

ABSTRACT=Upcycling and reclaiming of low quality or stored coal combustion fly ashes enables to tap into a voluminous resource of supplementary cementitious materials 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 paper compares the effect of size classification and milling treatments on the reactivity of a siliceous fly ash. The chemical reactivity is assessed using the R3 heat release test method and consumption of portlandite in blended cements. Both test results are used 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.