Abstract
This paper focuses on the development of a concrete material by utilizing fly ash and blast furnace slag in conjunction with coarse and fine aggregates with an aim to reduce pollution and eliminate the use of energy extensive binding material like cement. Alternative binding materials have been tried with an aim to get rather an improved concrete material. Alkali-Activated Solution (AAS) made of the hydroxide and silicate solutions of sodium was adopted as the liquid binder whereas, Class F” fly ash and Ground Granulated Blast Furnace Slag (GGBFS) mixed in dry state were used as the Geopolymer Solid Binder (GSB). The liquid binder was used to synthesize the solid binder by thermal curing. The paper investigates the use, influence and relative quantities of the liquid and solid binders in the development of the alkali-activated GGBFS based Geopolymer Concrete (GPC). Varying ratios of AAS to GSB were taken to assess their optimum content. Further, different percentages of GGBFS were used as a partial replacement of Class F fly ash to determine the optimum replacement of GGBFS in the GPC. In order to assess their effects on various properties test samples of cubes, cylinders and beams were cast and tested at 3, 7, and 28 days. Thermal curing of GPC has also resorted for favorable results. It was found that AAS to GSB ratio of 0.5 and GGBFS content of 80% yielded the maximum strength with a little unfavorable effect on workability. The overall results indicated that AAS and GGBFS offer good geopolymer concrete which will find its applicability in water scarce areas. Doi: 10.28991/cej-2021-03091708 Full Text: PDF
Highlights
The most widely used material to bind the constituents of conventional concrete has been Portland cement
The geopolymer concrete mixes were designed with the solid binder (GGBFS and fly ash), liquid binder (Alkaline activated solution), aggregates, and water
Reactive and excess water has participated in the hydration process and slump of Portland cement concrete respectively while water is used in Geopolymer Concrete (GPC) only for preparation of activated solution (AAS) and gaining workability
Summary
The most widely used material to bind the constituents of conventional concrete has been Portland cement. It has been reported that with the use of 75% fly ash, 25% slag and 14 M concentration of NaOH in preparation of geopolymer concrete yielded a compressive strength value of 35 MPa even at 28 days of ambient curing [7]. It is seen that most of the researchers emphasize broadly that the geopolymer concrete mixed with fly ash and alkali-activated solution (AAS) can yield the maximum compressive strength at a concentration of NaOH between 15.5 -16 M and at a ratio of silicate to hydroxide of sodium solution between 1.5-2.5. Very few investigations have reported about the mechanical properties of geopolymer concrete (GPC) containing fly ash and ground granulated blast furnace slag (GGBFS) and about the ratio of AAS to GSB. The mechanical properties of GPC containing various percentages of GGBFS as a partial replacement of fly ash, in order to achieve improvement in properties, have been investigated by conducting various experiments like compressive strength, flexural strength, modulus of rigidity and split tensile strength tests
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