Workability and strength of coarse high calcium fly ash geopolymer
TL;DR: In this article, the basic properties viz., workability and strength of geopolymer mortar made from coarse lignite high calcium fly ash were investigated, and the results revealed that the workable flow of the geopolymers was in the range of 110 −±5% −135 −± 5% and was dependent on the ratio by mass of sodium silicate to NaOH and the concentration of NaOH.
Abstract: In this paper, the basic properties viz., workability and strength of geopolymer mortar made from coarse lignite high calcium fly ash were investigated. The geopolymer was activated with sodium hydroxide (NaOH), sodium silicate and heat. The results revealed that the workable flow of geopolymer mortar was in the range of 110 ± 5%–135 ± 5% and was dependent on the ratio by mass of sodium silicate to NaOH and the concentration of NaOH. The obtained compressive strength was in the range of 10–65 MPa. The optimum sodium silicate to NaOH ratio to produce high strength geopolymer was 0.67–1.0. The concentration variation of NaOH between 10 M and 20 M was found to have a small effect on the strength. The geopolymer samples with high strength were obtained with the following practices: the delay time after moulding and before subjecting the sample to heat was 1 h and the optimum curing temperature in the oven was 75 °C with the curing duration of not less than two days.
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TL;DR: An overview of advances in geopolymers formed by the alkaline activation of aluminosilicates is presented along with opportunities for their use in building construction as mentioned in this paper, with respect to fresh and hardened states, interfacial transition zone between aggregate and geopolymer, bond with steel reinforcing bars and resistance to elevated temperature.
899 citations
TL;DR: In this paper, ground fly ash (GFA), with a median particle size of 10.5μm, was used as source material for making geopolymers cured at room temperature, and compressive strength tests and microstructure observations using SEM, EDX, XRD and FTIR were performed.
755 citations
Cites background from "Workability and strength of coarse ..."
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...Initial curing at elevated temperatures between 40 and 95 C improved geopolymerization, which led to a high compressive strength of the geopolymer [3,8,10,13]....
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693 citations
TL;DR: The results show that both fly ash and bottom ash can be utilized as source materials for the production of geopolymers and the moderate NaOH concentration of 10 M is found to be suitable and gives fly ashand bottom ash geopolymer mortars with compressive strengths of 35 and 18 MPa.
541 citations
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TL;DR: In this paper, the mechanism of activation of fly ash with highly alkaline solutions is described, and the product of the reaction is an amorphous aluminosilicate gel having a structure similar to that of zeolitic precursors.
1,779 citations
TL;DR: In this article, fly ash-based geopolymer concrete was developed to reduce greenhouse gas emissions, and the test results showed the effects of various parameters on the properties of the concrete.
Abstract: To reduce greenhouse gas emissions, efforts are needed to develop environmentally friendly construction materials. This paper presents the development of fly ash-based geopolymer concrete. In geopolymer concrete, a by-product material rich in silicon and aluminum, such as low-calcium (ASTM C 618 Class F) fly ash, is chemically activated by a high-alkaline solution to form a paste that binds the loose coarse and fine aggregates, and other unreacted materials in the mixture. The test results presented in this paper show the effects of various parameters on the properties of geopolymer concrete. The application of geopolymer concrete and future research needs are also identified.
797 citations
TL;DR: In this article, the effect of storing at room temperature before the application of heat on phase composition and phase composition was studied using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and SEM.
790 citations
TL;DR: In this paper, the relationship between composition and temperature on the final chemical and physical properties of a geopolymer derived from waste materials is investigated and it is shown that the differences in reactivity of source materials, used during the synthesis of waste-based geopolymers, significantly affect the final properties of the material.
781 citations
TL;DR: In this paper, the microscopic study of a set of alkali-activated and thermally cured fly ash samples enabled the authors to establish a descriptive model for the microstructural development of fly ash-based cementitious geopolymers.
664 citations