Geopolymer and Portland cement concretes in simulated fire

Zhao, Renfeng; Sanjayan, Jay

doi:10.1680/macr.9.00110

Cited by 195 publications

(70 citation statements)

References 23 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: 55%

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: 55%

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

Rovnanı́k¹

2015

Mater. Tehnol.

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“…The development of alkali-activated slag (AAS) cements has been object of intensive research recently [1]. The AAS cements are manufactured by mixing fine-ground glass slag with strong alkaline solutions, such as water glass NaOH and Na2CO3.…”

Section: Introductionmentioning

confidence: 99%

Impact of graphite admixture on electrical properties of alkali-activated slag mortars

Kusák¹,

Lunak²,

Rovnanı́k³

2017

MATEC Web Conf.

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One of the objectives of the applied research's striving consists in providing the users with new slag-mortar-based materials. Basic research, in its turn, aims at examining the newly created materials from the viewpoint of all possible testing methods. Slag mortar specimens were subjected to electrical analysis carried out by means of an ZNC vector analyser and an SPEAG-made DAK-12 coaxial probe within the frequency range from 100 MHz to 3GHz and, furthermore, a dedicated automatically measuring device within the frequency range from 40 Hz to 1 MHz. The frequency spectra of interest were measured on various copolymer specimens differing from each other by the content of the carbon powder. Higher graphite powder content increases the electrical conductivity of cement/slag-based building materials, which thus become easier to measure by means of electromagnetic measuring methods. Carbon admixture may also improve the material's antistatic properties.

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“…The mix design used in this research was based on the work reported by Zhao & Sanjayan [19] and is shown in Table 3. Aggregate weights shown in Table 3 are in the saturated surface dry condition.…”

Section: Designmentioning

confidence: 99%

Fibre-reinforced geopolymer concrete with ambient curing for in situ applications

2014

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Abstract:Geopolymer concrete is proven to have excellent engineering properties with a reduced carbon footprint. It not only reduces the greenhouse gas emissions (compared to Portland cement based concrete) but also utilises a large amount of industrial waste materials such as fly ash and slag. Due to these positive attributes, it is becoming an increasingly popular construction material. Previous studies on geopolymer concrete report that heat curing plays an important role in gaining higher compressive strength values (as opposed to ambient curing) and hence the application of this material could be limited to precast members. Therefore, this research was aimed at investigating the effect of heat curing by comparing the mechanical properties such as compressive strength and ductility of ambient cured and heat cured geopolymer concrete samples. It is worth noting that there was marginal strength change due to heat curing.In Australia fibre-reinforced geopolymer concrete is being used in precast panels in underground constructions. Commercially available geopolymer cement and synthetic fibres are effectively being used to produce elements that are more durable than what is currently used in industry. As a result, this research investigated the effects of polypropylene fibres in geopolymer concrete using 0.05% and 0.15% fibres (by weight). The addition of polypropylene fibres enhances the compressive strength and the ductility of geopolymer concrete.

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Geopolymer and Portland cement concretes in simulated fire

Cited by 195 publications

References 23 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

Impact of graphite admixture on electrical properties of alkali-activated slag mortars

Fibre-reinforced geopolymer concrete with ambient curing for in situ applications

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