Mechanical properties of alkali activated geopolymer paste using different Romanian fly ash sources – experimental results

Adrian Lăzărescu,Henriette Szilagyi,Călin Mircea,Cornelia Baeră,M.G Grantham,C Mircea

doi:10.1051/matecconf/201928911001

Abstract

As concrete demand is constantly increasing in recent years and also considering that cement production is both a consumer of natural resources and a source of carbon dioxide release into the atmosphere, there have been worldwide investigations into green alternatives for making concrete environmentally friendlier and simultaneously to satisfy the development of infrastructure facilities. The use of fly ash as a component of cementitious binders is not new but when considering the specific case of alkaline activation and fly ash representing the only source for the binder formation, it necessitates a more complete understanding of its specific reactions during the alkaline activation process. Since the fly ash varies dramatically, not only from one source to another, but also from one batch to another even when provided by the same power plant, its chemistry in obtaining alkali-activated materials during the geopolymerisation process and the final mechanical properties are considered crucial for the performance of geopolymer concrete. This paper will provide a review of the experimental results concerning the physical and mechanical evaluation of the alkali-activated fly ash-based geopolymer materials, developed with different types of fly ash, for a better understanding of geopolymer concrete production control.

Highlights

Concrete is the second most widely used material in the world, being considered the most versatile, durable and reliable building material - the need to produce large quantities of Portland cement (PC) as binder for concrete are constantly increasing
The aim of this paper is to present the preliminary results obtained on alkali-activated fly ash-based geopolymer paste using different Romanian power-plant source materials for producing this type of material, based on efficient source materials, available at national level and presenting the effect of their physical and chemical properties on the compressive strength of the binder
The physical and chemical properties of the fly ash samples, as well as the different ratios of alkaline liquid ratios, at the age of 7 days, and FAGPP compressive strength were consider relevant for the comparative evaluation of the above nominated parameters

Summary

Introduction

Concrete is the second most widely used material in the world, being considered the most versatile, durable and reliable building material - the need to produce large quantities of Portland cement (PC) as binder for concrete are constantly increasing. Alkaline activation of the fly ash represents a special procedure, able to generate the solidification of fly ash powder when mixing it with a certain type of alkaline activator and creating a new binding material. It has opened the perspective of obtaining a new building material when incorporating aggregates, as an alternative to traditional concrete and cementbased composites [4,5,6,7]. Developing these types of composites, with similar or even superior, properties to cementitious composites, without using cement in the composition, creates an extraordinary opportunity for the environment and for the construction industry, constituting itself as an alternative to traditional technology, both due to mechanical properties and high resistance in aggressive environments [8]

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Conclusion