Application of ultra-fine fly ash as cement replacement for sustainable concrete with optimal packing design

Conference paper (2021)

Authors

Patricija Kara De Maeijer University of Antwerp, Belgium
Bart Craeye University of Antwerp, Belgium - Odisee University College, Belgium
Hadi Kazemi-Kamyab VITO NV, Belgium
Ruben Snellings VITO NV, Belgium
Michel Loots Value Ash Technologies NV, Belgium
Copyright: © 2021 the authors
ASR Concrete Compressive strength Corrosion resistance Ultra-fine fly ash
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Published Date

29-04-2021

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Abstract

In the present study, a proprietary 0.2 tonne/h Dusty Cloud Separation (DCS) technology prototype by Value Ash Technologies NV (Belgium) was used to obtain ultra-fine fly ash as a novel by-product. Two types of Class F fly ash were used: separated fly ash (FA1) with particle size < 9.3 μm and ultra-fine fly ash (FA2) < 4.6 μm as sub-fraction of FA1. Two types of cement were used: Portland cement CEM I 52.5 R HES (CEMI) and Blast Furnace Slag Cement CEM III/A 42.5 N LA (CEMIII). The results at paste- and mortar- levels showed that an increased fineness of the fly ash (FA2) contributes to better workability of the mix. For CEMI, the compressive strength of concrete with FA2 with 25% cement replacement was already equal to the reference mix at the age of 28 days. For CEMIII, the compressive strength of concrete mix with FA2 with 25% cement replacement was equal to the reference mix value at the age of 91 days. Regarding the durability, replacing cement with ultra-fine fly ash (FA2) had a positive influence on the chloride migration coefficient and ASR, and a negative influence on the carbonation resistance.