Characterization of alkali activated slag paste after exposure to high temperatures

Rovnanı́k, Pavel; Bayer, Patrik; Rovnanı́ková, Pavla

doi:10.1016/j.conbuildmat.2013.06.070

Cited by 177 publications

(93 citation statements)

References 31 publications

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“…In contrast to the composites based on Portland cement, alkali-activated slag shows a much better performance when exposed to very high temperatures. [7][8][9] Similar to the case of Portland cement, a partial dehydration and decomposition of the binder can be observed up to 600°C. The principle changes in the microstructure of alkali-activated slag occur between 600°C and 800°C, when the dehydration of the C-A-S-H phase is complete and new phases start to crystallize, among which akermanite is dominant.…”

Section: Introductionmentioning

confidence: 65%

“…8 The main difference in the pore distribution appeared after the exposure to 600°C (Figure 3). There was an increase in the pore volume in the range of large capillary pores (1-10 μm) for the quartz composite, which can be clearly attributed to the reversible phase transition to high quartz, followed by an increase in the aggregate volume by approximately 4.5 %.…”

Section: Resultsmentioning

confidence: 99%

“…Since quartz is quite an inert phase that does not react with the AAS matrix even at a very high temperature, there was practically no difference between the XRD patterns of the quartz composite and the AAS matrix itself. 8 On the other hand, chamotte contains two main crystalline phases, quartz and mullite. The latter is not stable when such a high concentration of alkalis is present in the material and reacts with the AAS matrix to form two plagioclase phases, albite and anothite, at temperatures exceeding 1000°C (Figure 4).…”

Section: Resultsmentioning

confidence: 99%

“…Such a significant phase transformation is reflected in the morphology, pore distribution and, especially, in the improvement of the mechanical properties of the alkali-activated slag. 8 However, the properties of the composite materials with an AAS matrix after a high-temperature treatment also depend on the stability of the aggregates. The effects of two different types of the aggregate (quartz and chamotte) on the residual mechanical properties and microstructure of the alkali-activated slag mortars exposed to 200-1200°C is presented are this study.…”

Section: Introductionmentioning

confidence: 99%

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Effect of the aggregate type on the properties of alkali-activated slag subjected to high temperatures

Rovnanı́k¹

2015

Mater. Tehnol.

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High temperatures present a risk of destruction for most silicate-based construction materials. Although these materials are not flammable, they lose their properties due to a thermal decomposition. In contrast to ordinary Portland-cement-based materials, alkali-activated slag exhibits a better thermal stability when exposed to temperatures up to 1200°C. Due to its different porosity it is less susceptible to spalling. However, the properties of the composites after a high-temperature treatment depend also on the stability of the aggregates. The effects of two different types of the aggregate (quartz and chamotte) on the residual mechanical properties and microstructure of the alkali-activated slag mortars exposed to 200-1200°C is presented in this study. The results showed an improved mechanical performance of the thermally stable chamotte aggregate at temperatures above 600°C. a-quartz is transformed to b-quartz at 573°C, causing a volume instability and, consequently, a strength deterioration. Although chamotte also contains some quartz phase, the reaction of mullite with the alkalis from the matrix leads to the formation of albite and anorthite, making the material tougher and, thus, compensating the negative effect of quartz. Keywords: alkali-activated slag, high temperatures, chamotte, quartz, strength, microstructure Visoke temperature so tveganje za razpad ve~ine gradbenih materialov, ki temeljijo na silikatih.^eprav ti materiali niso vnetljivi, izgubijo svoje lastnosti zaradi termi~ne razgradnje. Nasprotno od materialov, ki temeljijo na portland cementu, z alkalijo aktivirane`lindre izkazujejo bolj{o temperaturno obstojnost,~e so izpostavljene temperaturam do 1200°C. Zaradi razli~ne poroznosti so manj ob~utljive za pojav lu{~enja. Vendar pa so lastnosti kompozita po visokotemperaturni obdelavi odvisne tudi od stabilnosti agregatov. V {tudiji so predstavljeni vplivi dveh razli~nih vrst agregatov (kremen in {amota) na preostale mehanske lastnosti in mikrostrukturo malte iz z alkalijo aktivirane`lindre, izpostavljene temperaturam 200-1200°C. Rezultati so pokazali izbolj{ane mehanske lastnosti toplotno stabilnega {amotnega agregata pri temperaturah nad 600°C. a-kremen se transformira pri 573°C v b-kremen, kar povzro~i volumensko nestabilnost in posledi~no poslab{anje trdnosti.^eprav {amot vsebuje nekaj kremenove faze, reagiranje mulita z alkalijami iz osnove povzro~i nastanek albita in anortita, ki povzro~ita, da material postane bolj`ilav in s tem kompenzira negativni vpliv kremena.

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Section: Introductionmentioning

confidence: 65%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of the aggregate type on the properties of alkali-activated slag subjected to high temperatures

Rovnanı́k¹

2015

Mater. Tehnol.

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“…It is also well-known that geopolymers possess excellent mechanical properties and fire resistance [9]. Geopolymers, in general, present a low thermal conductivity at high temperatures [10][11][12][13] and they do no emitted toxic fume when it is heated [14]. The fly ash geopolymer has good properties that allow it to be used as the shield, adding other materials such as barium sulphate to fly ash geopolymer to increase density and to improve the attenuation characteristics.…”

Section: Introductionmentioning

confidence: 99%

Effect of fly ash geopolymer with 15% barium Sulphate as a design shielding box on radiation attenuation using GafchramicXR-QA2 film dosimetry

Shalbi¹,

Jaafar²,

Ahmed³

et al. 2017

IOSR JEN

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Abstract:-This work was devotedto examining the effects of fly ash geopolymer mixed with 15% Barium Sulphate on radiation attenuation using Gafchramic XR-QA2 film. The fly ash geopolymer with 15% Barium Sulphate made high attenuation at energy of 120 KVp. In this study, the maximum radiation attenuation value of 99.43% was obtained by the design shielding box. The X-ray machine was used as a source for X-rays. While the Gafchramic XR-QA2 film dose was measured by the optical density equation, the ion chamber is used for dose measurement.

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Examination of mechanical properties and microstructure of alkali activated slag and slag‐metakaolin blends exposed to high temperatures

Akçaözoğlu

Çiflikli

Bozkaya

et al. 2021

Structural Concrete

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This paper reports an experimental study of the influence of elevated temperature on alkali activated slag (AAS) and slag-metakaolin (MK) systems. The residual compressive and flexural tensile strengths, ultrasonic pulse velocity (UPV) and porosity and water absorption ratios of AAS and AAS-MK composites after subjected to elevated temperatures of 200, 400, 600, 800, and 1000 C were investigated. Two different procedures were applied for cooling the specimens. The changes in the microstructure of the composites after subjected to high temperature were examined with scanning electron microscope and X-ray diffraction. Test results reveal that depending on the increasing temperature, the residual compressive strength, flexural tensile strength, and UPV values of the specimens decreased, and porosity and water absorption ratios increased. The minimum strength results of AAS and AAS-MK specimens were observed at 800 and 600 C, respectively. In particular, there have been significant changes in the internal structure of AAS and AAS-MK specimens exposed to 1000 C and new reaction products were observed. Test results have shown that AAS specimens are a new alternative that can be developed for use in environments exposed to high temperatures. Since this new composite contains only slag binder and slag aggregate, it can be an economical product that use fully recycled material and these properties can increase the application areas of environmentally friendly material.

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Characterization of alkali activated slag paste after exposure to high temperatures

Cited by 177 publications

References 31 publications

Effect of the aggregate type on the properties of alkali-activated slag subjected to high temperatures

Effect of the aggregate type on the properties of alkali-activated slag subjected to high temperatures

Effect of fly ash geopolymer with 15% barium Sulphate as a design shielding box on radiation attenuation using GafchramicXR-QA2 film dosimetry

Examination of mechanical properties and microstructure of alkali activated slag and slag‐metakaolin blends exposed to high temperatures

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