Investigation of Heat Released during Geopolymerization with Fly Ash based Geopolymer

Raiss, Mohamed; Razak, Rafiza Abd; Shuib, Raa Khimi; Mortar, Nurul Aida Mohd; Zailani, Warid Wazien Ahmad

doi:10.1088/1757-899x/551/1/012093

Cited by 19 publications

(5 citation statements)

References 4 publications

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“…If it is possible to reduce or control the setting time of geopolymers in the desired time, they could be used in a wider variety of fields where OPC and rapid-setting cement are used, such as in 3D printing and building maintenance. In order to control the setting of geopolymers, three setting control methods have been suggested: (1) the increasing of curing temperatures (heat curing), (2) the use of source materials with a high calcium content, and (3) the addition of calcium compounds [ 14 , 15 , 16 ]. Heat curing can significantly reduce setting time and accelerate geopolymerization [ 15 ], but it is difficult to apply to the production of site-poured concrete.…”

Section: Introductionmentioning

confidence: 99%

“…The use of source material with high calcium content such as class C fly ash can lead to fast setting at room temperature. The initial and final setting times for fly ash-based geopolymers fabricated using class C fly ash and cured at room temperature are 30 min and 1 h, respectively [ 16 ]. However, it is difficult to quantitatively control the setting of geopolymers because setting time is only unaffected by the calcium content in the fresh mix.…”

Section: Introductionmentioning

confidence: 99%

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Setting Behavior and Phase Evolution on Heat Treatment of Metakaolin-Based Geopolymers Containing Calcium Hydroxide

et al. 2021

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The setting behavior of geopolymers is affected by the type of source materials, alkali activators, mix formulations, and curing conditions. Calcium hydroxide is known to be an effective additive to shorten the setting period of geopolymers. However, there is still room for improvement in the understanding of the effect of calcium hydroxide on the setting and phase evolution of geopolymers. In this study, the setting behavior and phase evolution of geopolymer containing calcium hydroxide were investigated by XRD analysis. The setting time of the geopolymer was inconsistently shortened as the amount of calcium hydroxide increased. A low calcium hydroxide dose of up to 2% of the total mix weight could contribute to the enhancement of compressive strength of geopolymers besides a fast-setting effect. The C-S-H gel is rapidly precipitated at the early stage of reaction in geopolymers containing high calcium hydroxide with some of the calcium hydroxide remaining intact. The ex-situ high-temperature XRD analysis and Rietveld refinement results revealed that geopolymer and C-S-H gel transformed into Si-rich nepheline and wollastonite, respectively. The wollastonite was also observed in heat-treated geopolymers with a low calcium hydroxide dose. It is believed that C-S-H gel can be precipitated along with geopolymers regardless of how much calcium hydroxide is added.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Setting Behavior and Phase Evolution on Heat Treatment of Metakaolin-Based Geopolymers Containing Calcium Hydroxide

et al. 2021

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“…The first peak indicated the dissolution process, while the second peak indicated the polymerisation peak, respectively [ 38 ]. Moreover, Mohamed et al (2019) reported a high amount of heat released during the dissolution process with a value of −43.5067 J/g by using a class C fly ash to AA ratio of 2.5, whereby the ratio used was similar to the ratio used in this study [ 39 ].…”

Section: Resultsmentioning

confidence: 97%

“…However, Bosenick et al (2000) mentioned that bond ordering energies in minerals (Si and Al) are insensitive to composition provided that the variation is only in the ratio of the ordering cations, and so any possible dependence of cations present and the positions will not be considered [37]. Previous studies conducted by Ling et al and Mohamed et al also proved that the dissolution reaction was exothermic [38,39]. Ling et al (2019) reported that two major exothermic peaks were observed in a calorimetric curve using a semi-isothermal calorimetry device.…”

Section: Geopolymer Concrete Preliminary Design Characteristicmentioning

confidence: 99%

Thermal Properties and Drying Shrinkage Performance of Palm Kernel Shell Ash and Rice Husk Ash-Based Geopolymer Concrete

Abdullah,

Mustapha,

Yusof

et al. 2024

Materials

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This study aims to develop suitable formulations of geopolymer concrete (GPC) by varying the percentages of the geopolymer with aggregates and evaluating the performances in thermal and mechanical properties of palm kernel shell ash (PKSA)-GPC compared to rice husk ash (RHA)-GPC and ordinary Portland cement concrete (OPCC). Preliminary tests were conducted to select the best mix design ratios before casting the specimens. Then, the performance of the PKSA-GPC, RHA-GPC and OPCC specimens was evaluated based on their thermal performance and drying shrinkage. The mix designs of PKSA-GPC 70:30, PKSA-GPC 60:40, PKSA-GPC 50:50 and PKSA-GPC 66.6:33.3 were found to produce an acceptable consistency, rheological and thixotropic behaviour for the development of the GPC. PKSA-GPC showed a better thermal performance than the RHA-GPC and OPCC due to their strong and dense intumescent layers and slow temperature increment upon exposure to a high flame temperature from ambient temperature to 169 °C. The low molar ratio of the Si/Al present in the PKSA-GPC created a thermally stable intumescent layer. In the drying shrinkage test, PKSA-GPC 60:40 and RHA-GPC 60:40 shared an equal drying shrinkage performance (5.040%) compared to the OPCC (8.996%). It was observed that microcrack formation could significantly contribute to the high shrinkage in the PKSA-GPC 50:50 and RHA-GPC 70:30 specimens. The findings of this study show that PKSA could be incorporated into GPC as a fire-retardant material due to its capability of prolonging the spread of fire upon ignition and acting as an alternative to the conventional OPCC.

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“…This is because of the increase in OHanions concentration, resulting in the quick dissolution of fly ash particles at early stages (Naghizadeh and Ekolu 2021). The increase in solid to liquid content beyond a certain limit ultimately resulted in quick hardening and gelation due to an excessive rise in an exothermic reaction (Mohamed et al 2019). The configuration of SCGM paste because of rapid gel formation is shown in Fig.…”

Section: Effect Of Geopolymer Molar Ratios On the Flow Properties Of ...mentioning

confidence: 99%

Performance of Superplasticizers in Alkaline Environment of Self Compacting Geopolymer Mortar

Ghafoor

Fujiyama

2022

ACT

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Self-compacting geopolymer concrete (SCGC) is a revolutionary concept in the construction industry. This study fills the research gap by determining the impact of six different types of commercially available superplasticizers on the flow properties, dry density and compressive strength of SCGM. It was investigated that the relationship between relative flow area (G m ) and relative flow speed (R m ) of SCGM depends on the type of superplasticizer. The test results exhibited that a polyaryl ether-based superplasticizer performed better in increasing the flow deformability and flow speed of SCGM in comparison to melamine-based and naphthalene-based superplasticizers. The excessive increase in air content of SCGM paste with the addition of some superplasticizers had a negative impact on the flow properties. The increase in sodium oxide to silica molar ratio (Na 2 O/SiO 2 ) and sodium oxide to water molar ratio (Na 2 O/H 2 O) both had a negative impact on the flow properties of SCGM. It was determined that beyond a trigger value of Na 2 O/SiO 2 of 0.171, the impact of the superplasticizer in separating the flowing particles of SCGM became insignificant, resulting in the flash setting. Moreover, the addition of each type of superplasticizer had a negative impact on the dry density and compressive strength of SCGM.

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Investigation of Heat Released during Geopolymerization with Fly Ash based Geopolymer

Cited by 19 publications

References 4 publications

Setting Behavior and Phase Evolution on Heat Treatment of Metakaolin-Based Geopolymers Containing Calcium Hydroxide

Setting Behavior and Phase Evolution on Heat Treatment of Metakaolin-Based Geopolymers Containing Calcium Hydroxide

Thermal Properties and Drying Shrinkage Performance of Palm Kernel Shell Ash and Rice Husk Ash-Based Geopolymer Concrete

Performance of Superplasticizers in Alkaline Environment of Self Compacting Geopolymer Mortar

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