Abstract
Geopolymer is a new sustainable binding material. It was developed to reduce CO2 footprint of existing Portland cement concrete. One ton of Geopolymeric cement generates 0.18 ton of CO2 from combustion carbon-fuel. This figure is 6 times less than the emission of Portland cement manufacture. The relationship between the compressive strength of Geopolymer concrete and the percentage of amorphous silica in the source material has been studied in the present work. Six mixes with different source materials were investigated to verify this relationship. The used Pozzolanic materials were three types of Fly ash, two types of Metakaolin and one type of ground granulated blast furnace slag. Geopolymer concrete samples were cured by heating for 72 hours. The testing ages for compressive strength were 7, 14, 28, and 60 days. The results showed that a noticeable relationship between compressive strength and amorphous silica was observed. The microstructure of the six mixes was studied in detail through the SEM and XRD analysis.
Highlights
Davidovits [1] stated that the geopolymerization process involves a reaction between alkaline liquids and compounds containing alumina and silica to produce a binder
Duxson et al [4] showed that the fundamental chemical and structural characteristics of Geopolymers derived from Metakaolin, Fly ash and slag are explored in terms of the effects of raw material selection on the properties of Geopolymer composites
Five types of Geopolymer concrete studied to know the effect of amorphous silica content in the raw materials on compressive strength development
Summary
Davidovits [1] stated that the geopolymerization process involves a reaction between alkaline liquids and compounds containing alumina and silica to produce a binder. Duxson et al [4] showed that the fundamental chemical and structural characteristics of Geopolymers derived from Metakaolin, Fly ash and slag are explored in terms of the effects of raw material selection on the properties of Geopolymer composites. The XRD diffractogram labeled b in Fig. is of a Geopolymeric gel with nominal composition NaAlSiO4, synthesized from Metakaolin (diffractogram a) in a 35 wt% water activating solution at 40 _C, 1 day after synthesis This material appears amorphous to XRD initially, evidence of the same reaction mechanism being responsible for the formation of Geopolymer and crystalline zeolite can be observed, with the formation of zeolite observed within 7 days of synthesis (diffractogram c). The objective of this paper was to study the effect of amorphous silica in different source materials on the strength development of Geopolymer concrete
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