Influence of admixtures on the properties of alkali-activated slag mortars subjected to different curing conditions

Bilim, Cahit; Karahan, Okan; Atiş, Cengiz Duran; İlkentapar, Serhan

doi:10.1016/j.matdes.2012.08.049

Cited by 128 publications

(44 citation statements)

References 34 publications

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“…These differences are caused by the different composition of the mixtures (particularly the SiO 2 to Na 2 O ratio of the activator) and are most likely due to the different origins of the additives used. Bilim et al used SRA based on polypropylene glycol in both aforementioned studies 25,26 , while the SRA used in the present study was based on 2-methyl-2,4-pentanediol. This indicates a strong dependence in the behaviour of AAS on the composition of commercially available SRAs originally developed for PC-based systems.…”

Section: Resultsmentioning

confidence: 98%

“…Therefore, they contain a lower amount of binding phase, which is associated with higher porosity and 25 did not observe a significant difference in the carbonation depth of the samples with and without SRA activated by solid sodium silicate. When C. Bilim et al 26 used liquid sodium silicate, the carbonation resistance of AAS mortars was even better in the presence of SRA. These differences are caused by the different composition of the mixtures (particularly the SiO 2 to Na 2 O ratio of the activator) and are most likely due to the different origins of the additives used.…”

Section: Resultsmentioning

confidence: 99%

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Influence of chemical additives and curing conditions on the mechanical properties and carbonation resistance of alkali-activated slag composites

Bulejko¹,

Bílek²

2017

Mater. Tehnol.

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The main aim of the presented work is to investigate the effect of the addition of air-entraining (AEA) and shrinkage-reducing agents (SRA) on the mechanical properties and carbonation resistance of alkali-activated slag (AAS). The materials used for the sample preparation were blast-furnace slag activated using sodium silicate and AEA or SRA in various amounts. The samples were cured in various conditions (air curing under laboratory conditions and water curing at the same temperature) and the influence of these was also studied. The prepared samples (specimens with dimensions of 100 mm × 20 mm × 20 mm) were tested for compressive and bending strengths. The experimental results show that the addition of AEA did not have a significant influence on the mechanical properties, while the addition of SRA had a negative effect. However, the carbonation resistance markedly decreases with an increase of both agents. The same is true for air curing, as mechanical strengths are lower compared to those samples cured in water, and the ratio of the strength of the air-cured composite and that of the water-cured composite decreases with an increase in the content of SRA. Keywords: alkali-activated slag, carbonation resistance, chemical additives, mechanical properties Glavni namen tega dela je preiskava vpliva dodatka za zmanj{anje vsebnosti zraka (angl. AEA) in dodatka za zmanj{anje kr~enja (angl. SRA) na mehanske lastnosti in odpornost na karbonacijo z alkalijami aktivirane`lindre (angl. AAS). Materiali za pripravo vzorcev so bili plav`na`lindra, aktivirana z natrijevim silikatom in razli~nim dodatkom AEA ali SRA. Vzorci so bili strjeni pri razli~nih pogojih (strjevanje na zraku v laboratorijskih pogojih in strjevanje v vodi pri enaki temperaturi) in {tudiran je bil njihov vpliv. Pripravljeni vzorci, z merami 100 mm × 20 mm × 20 mm, so bili preizku{eni na tla~no in upogibno trdnost. Rezultati preiskav ka`ejo, da dodatek AEA ni imel pomembnega vpliva na mehanske lastnosti, medtem ko je dodatek SRA nanje vplival negativno. Vendar pa se je odpornost na karbonacijo mo~no zmanj{ala z ve~anjem vsebnosti obeh dodatkov. Enako velja za strjevanje na zraku, saj so mehanske lastnosti slab{e v primerjavi z vzorci, strjenimi v vodi in se razmerje trdnosti vzorcev strjenih v vodi in razmerje trdnosti na zraku strjenih kompozitov, zmanj{a s pove~anjem vsebnosti SRA. Klju~ne besede: z alkalijami aktivirana`lindra, odpornost na karbonacijo, kemijski dodatki, mechanske lastnosti

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Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

Influence of chemical additives and curing conditions on the mechanical properties and carbonation resistance of alkali-activated slag composites

Bulejko¹,

Bílek²

2017

Mater. Tehnol.

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“…6 A limited number of studies concerning the use of SRAs in AAS are available. C. Bilim et al 9 and also M. Palacios and F. Puertas 10 reported a reduction in shrinkage through the use of an SRA based on polypropylene glycol, especially in the case of moist curing. T. Bakharev et al 11 achieved a lower shrinkage thanks to some non-standard SRA and also when using some air-entraining agent.…”

Section: Introductionmentioning

confidence: 97%

Effect of a combination of fly ash and shrinkage-reducing additives on the properties of alkali-activated slag-based mortars

Bílek¹,

Kalina²,

Koplík³

et al. 2016

Mater. Tehnol.

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This study is aimed at reducing the drying shrinkage of alkali-activated slag (AAS) through the use of low-calcium fly ash (FA) and commercially available shrinkage-reducing additives (SRAs) originally developed for OPC-based binders, since there are no such admixtures tailored for AAS systems. Generally, all the SRAs tested are based on modified alcohols. All the mortars were based on slag activated by waterglass, with the water-to-slag ratio equal to 0.40 and the sand-to-binder ratio 2:1. In the first step, the effect of the partial replacement of slag by FA (25, 50 and 75) % of mass fractions on the drying shrinkage and compressive strength was investigated. On the basis of the obtained results a mortar with 50 % FA in the binder was chosen for subsequent experiments, where the influence of three types of SRAs on the drying-shrinkage behaviour was examined. It was observed that while 25 % of the FA did not affect the drying shrinkage significantly, 50 % and 75 % of FA in the binder decreased the drying shrinkage by 57 % and 78 %, respectively. However, with an increasing content of FA, the compressive strength markedly decreased. All the tested SRAs had a similar effect on the drying shrinkage of the slag/fly ash (50/50) mortar: at a dose of 0.50 % (by mass of slag) the shrinkage was reduced only slightly, whereas 1.0-3.0 % of SRA resulted in a decrease by 49-66 %. Also, the drying shrinkage rate during the first days of drying was modified. However, all the SRAs reduced the compressive strength as compared to the neat slag-FA mortar, especially when the doses were higher than 0.50 %. Keywords: alkali-activated slag, fly ash, shrinkage reducing additives, shrinkage, strength Namen {tudije je zmanj{anje kr~enja pri su{enju z alkalijami aktivirane`lindre (AAS) z uporabo lete~ega pepela (FA), z majhno vsebnostjo kalcija in komercialno dostopnega dodatka za zmanj{anje kr~enja pri su{enju (SRA), originalno razvitega za veziva na osnovi OPC, ker do sedaj ni bilo takega dodatka primernega za AAS sisteme. Na splo{no so vsi preizku{eni SRA temeljili na modificiranih alkoholih. Vse malte so bile iz`lindre, aktivirane z vodnim steklom, z razmerjem voda:`lindra (0,40) in pesek:vezivo v razmerju 2:1. Na prvi stopnji je bil preiskovan vpliv delne nadomestitive`lindre s FA (25, 50 in 75) % masnih odstotkov, na kr~enje pri su{enju in na tla~no trdnost. Na osnovi dobljenih rezultatov je bila za nadaljevanje preizkusov izbrana malta s 50 % FA v vezivu, kjer se je preiskoval vpliv treh vrst SRA na skr~ek pri su{enju. Opa`eno je bilo, da medtem ko 25 % FA ni vplivalo pomembno na skr~ek pri su{enju, je 50 % in 75 % FA v vezivu, zmanj{alo skr~ek pri su{enju za 57 % oziroma 78 %. Vendar pa se je z nara{~ajo~im dele`em FA tla~na trdnost opazno zmanj{ala. Vse preizku{ene SRA so imele podoben vpliv na kr~enje pri su{enju malte, z razmerjem`lindra:lete~i pepel (50:50), pri koli~ini 0,50 % (masa:`lindra) se je skr~ek zmanj{al samo delno, medtem ko se je pri 1,0-3,0 % SRA skr~ek zmanj{al za 49-66 %. V prvih dneh se je spremenila tudi hit...

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“…In addition, materials having pozzolanic properties, such as fly ash (type F), slag, and SF are receiving attention as sustainable supplementary cementitious materials [14][15][16][17][18]. Along with the environmental and economic benefits as replacements for OPC, these materials also have other advantages, such as improving mechanical properties and durability [19].…”

Section: Introductionmentioning

confidence: 99%

Intensified Pozzolanic Reaction on Kaolinite Clay-Based Mortar

et al. 2017

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Abstract:The objective of this study is to develop and characterize kaolinite clay-based structural mortar. The pozzolanic reaction induced from two mineral additives, i.e., calcium hydroxide and silica fume (SF), and the physical filling effect from SF, were found to be effective on the enhancement of structural properties. Based on several preliminary experiments, 7:3 ratio of kaolinite clay/calcium hydroxide was selected as a basic binder. Then, the amount of SF was chosen as 0%, 7.5%, and 15% of the total binder to consider both the chemical and physical effects. The results showed that compressive strengths of samples with 7.5% and 15% SF are significantly increased by approximately 200% and 350%, respectively, at 28 days compared to the sample without SF. However, based on the results of the sample with 15% SF, it is found that excessive addition of SF causes long-term strength loss, possibly owing to micro cracks. With the careful consideration on this long-term behavior, this suggested new mix design can be further extended to develop sustainable structural materials using natural minerals or waste materials with nonbinding properties.

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Influence of admixtures on the properties of alkali-activated slag mortars subjected to different curing conditions

Cited by 128 publications

References 34 publications

Influence of chemical additives and curing conditions on the mechanical properties and carbonation resistance of alkali-activated slag composites

Influence of chemical additives and curing conditions on the mechanical properties and carbonation resistance of alkali-activated slag composites

Effect of a combination of fly ash and shrinkage-reducing additives on the properties of alkali-activated slag-based mortars

Intensified Pozzolanic Reaction on Kaolinite Clay-Based Mortar

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