Strength and Setting Times of Low Calcium Fly Ash-based Geopolymer Mortar

Hardjito, Djwantoro; Cheak, Chua Chung; Ing, Carrie Ho Lee

doi:10.5539/mas.v2n4p3

Cited by 179 publications

(107 citation statements)

References 10 publications

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“…It also has been shown to affect the workability of a mixture for both low calcium [43] and high calcium [17] fly ash based geopolymer concretes. This trend of water content affecting on the workability and later on compressive strength is the same with the conventional Portland cement concrete, where the chemical reaction involved is hydration process [44]. Furthermore, from the review of some previous studies, it seems that variation in chemical composition of the fly ash has less effect on the workability, with the exclusion of flash setting problems.…”

Section: Fresh State Behaviorsmentioning

confidence: 66%

“…Some researches which utilize low calcium fly ash [44,46] indicates that the reaction of geopolymerization would not start without elevated temperature curing and did not harden for at least one day. On the other side, a work conducted by Somna et al [47] shows that curing in the room temperature is possible when utilizing the high calcium fly ash with a high concentration of alkaline activator.…”

Section: Fresh State Behaviorsmentioning

confidence: 99%

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A review on the effect of fly ash characteristics and their variations on the synthesis of fly ash based geopolymer

Wattimena¹,

Antoni²,

Hardjito³

2017

AIP Conference Proceedings

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Abstract. There are more than four decades since the last 1970s where geopolymers concrete was first introduced and developed to use as a replacement to conventional concrete material which uses cement as a binder. And since the last two decades, geopolymers which utilized fly ash as aluminosilicate source material, i.e. fly ash based geopolymers, have been investigated. Many researchers present how to produce the best fly ash based geopolymer with a various source of constituent material as well as mixing formula to achieve exceptional concrete performance. Although there is a similar trend towards factors affecting the result of fly ash based geopolymer synthesis, there is still remain a wide range in mixture proportion. The considerable variation in fly ash characteristics as source material in the synthesis can very likely be one of the causes of this problem. This paper attempts to identify the effect of source material variation of geopolymer concrete, particularly which use fly ash as source material and focuses on the variation of its characteristics and the effects to properties of concrete. From the reviews it concluded that different sources (and even the same source, but different batch) of fly ash materials will give some different characteristics of the fly ash, where it would affect the synthesis process of the fly ash based geopolymer concretes.

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Section: Fresh State Behaviorsmentioning

confidence: 66%

Section: Fresh State Behaviorsmentioning

confidence: 99%

A review on the effect of fly ash characteristics and their variations on the synthesis of fly ash based geopolymer

Wattimena¹,

Antoni²,

Hardjito³

2017

AIP Conference Proceedings

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“…It has been found that the compressive strength is proportional to the concentration of NaOH solution and reaches the maximum value 25.48 MPa at 12 M (Figure 8). The literature [26,27] showed that the increase in the concentration of hydroxyl ions leads to the following reaction processes: (1) the liberation of Si and Al ion species from aluminosilicate raw materials; (2) the formation of stronger ion pairs; and (3) the acceleration of polycondensation rates. These processes all contribute to the development of geopolymer strength.…”

Section: Effect Of Naoh Concentrationmentioning

confidence: 99%

Building up and Characterization of Calcined Marl-Based Geopolymeric Cement

2018

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Abstract:The present study mainly investigates the synthesis of calcined marl-based geopolymeric cement under different synthesis conditions including NaOH concentration, sodium silicate (SS)/sodium hydroxide (SH) mass ratios, solid (S)/liquid (L) mass ratios, calcination temperatures, curing temperatures, curing times, and aging intervals. The studied head sample was obtained from the Abu-Tartur phosphate mine in the Western Desert of Egypt and subjected to chemical and mineralogical characterizations using X-ray fluorescence (XRF), X-ray diffraction (XRD), and Fourier transform-infrared spectroscopy (FT-IR). Regarding calcination, this was conducted at 550, 650, 750, and 850 • C for one hour and resulted in thermal decomposition of calcite and saponite and the formation of new mineral phases including anthophyllite, wollastonite, and silica. On the other hand, the geopolymerization process was initiated by mixing the calcined marl sample with the alkali activation solution at different mixing ratios and varying curing conditions. The compressive strength measurements indicate that 750 • C, 12 M NaOH, 0.6 SS/SH mass ratio, 2 S/L mass ratio, 80 • C curing temperature, 12 h curing time, and 28 days aging time are considered all to be the optimum synthesis conditions of the Abu-Tartur calcined marl-based geopolymer.

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“…Low CaO content in ash lengthens setting time [6,7] states that low-calcium ash-based geopolymers ordinarily have a setting time of nearby 2 hours. Previous study [8] revealed factors affecting setting time of matrices are morphology, reactivity and Ca content of ash.…”

Section: Introductionmentioning

confidence: 99%

A Study on Factors Affecting Geopolymerization of Low Calcium Fly Ash

Tajunnisa¹

2017

GEOMATE

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This paper presents some factors affecting geopolymerization of low calcium fly ash for geopolymeric matrices. Low calcium fly ash samples were collected from two different coal-powered facilities: an Indonesian fertilizer plant and a Japanese power plant. Several series of tests were conducted using various ratios of fly ash to activator as well as ratios of activators to sodium hydroxide molarity. Each matrix consisted of a set molar ratio of three variations of Si/Al (1.5, 2, 2.5), Na2O/SiO2 (0.3-0.38), H2O/SiO2 (2.8 to 3.5), H2O/Na2O (9 to 10.6), and mass ratio of water/solid (0.31 to 0.45). The setting time of Japanese ash-matrices were longer than Indonesian ash. The compressive strength revealed that the Japanese and Indonesian matrices with activator ratios of 1.5 achieved 47.7 and 57.5 MPa respectively, while activator ratios of 2.5 reached 50.9 and 50.5 MPa. In addition, microstructural characterizations-XRF, XRD, SEM, EPMA-were performed. This study concludes that even ashes categorized as the same class, their mineral composition is different. Furthermore, coal combustion techniques modify ash particles, which in turn causes differences in setting time, while strength is not significantly affected.

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Strength and Setting Times of Low Calcium Fly Ash-based Geopolymer Mortar

Cited by 179 publications

References 10 publications

A review on the effect of fly ash characteristics and their variations on the synthesis of fly ash based geopolymer

A review on the effect of fly ash characteristics and their variations on the synthesis of fly ash based geopolymer

Building up and Characterization of Calcined Marl-Based Geopolymeric Cement

A Study on Factors Affecting Geopolymerization of Low Calcium Fly Ash

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