Effect of Biomass Fly Ash on Fresh and Hardened Properties of High Volume Fly Ash Mortars

Fernando Branco,Elisabete Teixeira,Aires Camões,José Matos

doi:10.3390/cryst11030233

Fernando Branco, Elisabete Teixeira + Show 2 more

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https://doi.org/10.3390/cryst11030233

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Journal: Crystals	Publication Date: Feb 26, 2021
Citations: 14	License type: CC BY 4.0

Affiliation: University of Coimbra, University of Minho

Abstract

The objective of this work was to assess the use of biomass fly ash (BFA) as cement replacement material or as an alkalinity source in high volume fly ash mortar and concrete. Mortar formulations were prepared with different types of cement replacement: fly ash from thermal power plants, BFA, a blend of two pozzolans, and small amounts of BFA or/and hydrated lime (HL). Mortar formulations were tested both in the fresh and hardened state. The replacement of cement by the two fly ashes led to a decrease in the mechanical strength. The best strength values were obtained when higher HL content was introduced in mortars, however, mortars with the lower BFA content presented the best results for the majority of the tests. In general, BFA has a similar effect on cementitious mortars to coal fly ash, having good performance as cement replacement.

Highlights

Nowadays, the Green and Circular Economy is gaining standing among academics and policy markets worldwide [1,2]
The results showed that 25% of cement replacement by biomass fly ash (BFA) led to mechanical properties that could be considered statistically similar to those achieved with coal fly ash (CFA) concrete [19,33]
One may observe that mortars with 50%wt of cement replaced by BFA and with cement replaced by BFA (48.5%wt) and hydrated lime (HL) (1.25%wt) presented flow spread values similar to those observed for the reference formulation, and in some cases lower than reference

Summary

Introduction

The Green and Circular Economy is gaining standing among academics and policy markets worldwide [1,2] This green economy results in “improved human well-being and social equity, while significantly reducing environmental risks and ecological scarcities” [2]. A great number of biomass resources are used in several industrial sectors to produce heat and power process applications and the national electric grid, as it happens, in the pulp and paper production and wood and furniture industry In those sectors, the raw biomass feedstock preparation generates significant amounts of residual biomass that is valorized in energetic applications as fuel in thermochemical conversion processes, mostly combustion [3,6,7,8,9,10]

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