Mechanisms of air entrainment in concrete

Du, Lianxiang; Folliard, Kevin J.

doi:10.1016/j.cemconres.2004.07.026

Cited by 402 publications

(183 citation statements)

References 8 publications

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“…This is explained by the fact that the surfactant molecules tend to minimize unfavorable interactions between the liquid phase and the surfactant lipophilic tail, aligning to form a monolayer at the interface between the liquid phase and the compressed air. The air bubbles are stabilized in the slurry by the electrostatic and steric repulsions of the surfactants; the interfacial properties at the air bubble surfaces are determined by its physical and chemical properties given by the nature and concentration of the surfactants [19]. This surfactant foaming ability has been well established and studied by other authors [19,46,49,70,73].…”

Section: Mechanical Behavior Of Compositesmentioning

confidence: 89%

“…The air bubbles are stabilized in the slurry by the electrostatic and steric repulsions of the surfactants; the interfacial properties at the air bubble surfaces are determined by its physical and chemical properties given by the nature and concentration of the surfactants [19]. This surfactant foaming ability has been well established and studied by other authors [19,46,49,70,73]. Nevertheless, in presence of aerogel particles, no stabilized air bubbles within the composites were detected; although, an important amount of air entrained is measured.…”

Section: Mechanical Behavior Of Compositesmentioning

confidence: 95%

“…They are mostly used in the manufacture of detergents, soaps and many other personal care products. In building applications, surfactants have been used recently to form mineral slurries with hydrophobic aerogel particles [10,18,36], besides other uses, like air-entraining agent to produce freeze-thaw resistant concrete, but also foamed concrete [19,46,49,70,73]. However, their use in cement-free based composites has received comparatively little attention.…”

Section: Introductionmentioning

confidence: 99%

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Anhydrite/aerogel composites for thermal insulation

et al. 2015

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High performance thermal insulating composite materials can be produced with mineral binders and hydrophobic aerogel particles through a hydrophilization process for the latter with surfactants. The present study is focused on the development of aerogel/calcium sulfate composites by the hydrophilization of hydrophobic silica aerogel particles through a polymer-based surfactant. Its effects on the microstructure and hydration degree are examined as well as their relation to the resulting mechanical and physical properties. Results show that composites with an around 60 % of aerogel by volume can achieve a thermal conductivity \30 mW/m 9 K. Interestingly, a surfactant addition of 0.1 % by wt% of the water in the mixtures provides better material properties compared to a surfactant wt% addition of 5 %. However, it has been found around 40 % entrained air, affecting the material properties by reducing the binder and aerogel volume fractions within the composites. Moreover, gypsum crystallization starts to be inhibited at aerogel volume fractions [35 %. Towards material optimization, a model for the calculation of thermal conductivity of composites and an equation for the compressive strength are proposed.

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Section: Mechanical Behavior Of Compositesmentioning

confidence: 89%

Section: Mechanical Behavior Of Compositesmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

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Anhydrite/aerogel composites for thermal insulation

et al. 2015

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“…Her ne kadar süper akışkanlaştırıcılar köpüğün kararlılığını azaltsa da uygun işlenebilirliği sağlayabilmektedir [9,10]. Günümüzde yapı kimyasallarının karmaşıklığı nedeniyle köpük ile etkileşimleri genellenemez [11].…”

Section: Marsh Koni̇si̇ Yöntem İle Akişkanlik öZeli̇kleri̇ni̇n İncelenmesi̇unclassified

Köpük Betonun Reolojik Özelliklerinin Deneysel Olarak İncelenmesi

Demir¹,

Başpınar²,

Kahraman³

2017

CSJ

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Özet. Köpük beton harcı akış özellikleri geneleneksel harçtan farklıdır. Akma dayanımı çok düşük olduğu için kendiliğinden akış özelliği gösterir. Köpük betonun akış özelliklerini belirleyen bir çok faktör vardır. Temel olarak; su/çimento oranı, su/ince malzeme oranı, çimento tipi, köpük ajanının tipi, köpük yoğunluğu, filler malzeme tipi ve miktarı, taze harcın yoğunluğu vb. Bu nedenle nihai beton ve köpük betonun reolojik özellikleri arasında bir yakınlık görülebilir. Köpük betonun bilinen reolojik özellikleri harcın işlenebilirliği, pompalanabilirliği ve kararsızlığı hakkında bilgiler verir. Köpük betonun reolojik özelliklerinin belirlenmesinde en önemli iki faktör olan fiziksel ve mekaniksel özellikler iki farklı yöntemle incelenmiştir. Bu akış özellikleri Marsh konisi yöntemi ve Barookfield viskozimetresi ile incelenmiştir.Anahtar Kelimeler: Köpük beton, Reoloji, İşlenebilirlik, Viskozite, Marsh konisi Experimental Investigation of Foam Concrete Rheological PropertiesAbstract. The flow properties of foam concrete mortar are different from the traditional mortar. It is shows self flow properties for yield strength is very low. There are many factors that determine the flow properties of foam concrete. Basically they said; water/cement ratio, water /powder ratio, type of cement, the type of foaming agent, the foam density, the type filler material and amount of, the density of the fresh mortar, etc. Therefore can be established a close relationship between the rheological properties of foam concrete and the final concrete properties. To be known the rheological properties of foam concrete offers important information about the workability of mortar, pumpability and instability. Rheological properties of foam concrete have been investigated in two different methods as the most important factors that determine the physical and mechanical properties. This was investigated by flow properties Marsh cone method and Brookfield viscometer. Keywords:Foam concrete, Rheology, Workability, Viscosity, Marsh Cone GİRİŞKöpük betonun taze haldeki durumu geçici olmakla birlikte, sertleşmiş beton özelliklerine olan etkisi büyük önem taşır [1]. Reolojik çalışmalarda uçucu kül filler malzeme olarak kullanıldığında, kum kullanılan örneklere göre çok daha fazla yayılma göstermiştir. Kıvam ve reolojik özellikler agreganın tane şekli ve tane boyutu dağılımı ile yakından ilgilidir. Uçucu kül kütlece kum ile yer değiştirdiğinde ince tane oranı artacağından akışkanlıkta azalma gerçekleşecektir. Bu durumda istenen kıvamı elde etmek amacı ile su/toz oranın artırılması gerekir [2]. Karışımdaki köpük miktarının artması akışkanlığı azaltmaktadır. Bunun nedeni: 1) Hava hacmimin artması ile birlikte yoğunluğun azalması sonucu kohezyonun artışı neden olur [3]. 2) Harçtaki kabarcıklar ve katı taneler arasındaki adezyon kuvvetleri harcın kıvamını artırır. Görece katı kıvamda bir köpük beton karışımda, hava kabarcıklarının sönümlenmesine yol açarken, yüksek kıvamlı (aşırı akışkan) bir karışımda ise bünyesindeki hava kabarcıklarını tutma yeteneğin...

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“…The generated pore system increases the durability to freeze--thaw cycles (Du & Folliard, 2005;Marsh. D, 2015).…”

Section: Introductionmentioning

confidence: 99%

Use of Linear Alkylbenzene Sulfonate (Las) and Polycarboxylate-Ether (Pce) as Reagents in Iron Ore Flotation

Carvalho

Vasconcelos

Moreira

et al. 2017

HOLOS

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Flotation is one of the separation techniques that has been used by the mineral industry and its importance has increased due to its better performance in the concentration of low grade ores. Specific chemical reagents are used in flotation in order to promote the hydrophobicity control of minerals dispersed in a pulp, among them, surfactants have been studied with good results. In this study, a substance based on Linear Alkylbenzene Solfonate (LAS), and a concrete admixture based on Policarboxilate--ether (PCE) were tested as reagents in iron ore flotation. The tests were performed in a friable hematite sample, using the microflotation technique. The Yates complete replicated factorial method for three variables and two levels was used in experimental planning. The variables evaluated was pH (9--11); LAS content (1000--5000 g/cm³); and PCE content (100--1000 g/cm³). The best result (84.1% floated) was obtained for combination pH=9, LAS content = 5000 g/cm³ and PCE content = 100 g/cm³

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Mechanisms of air entrainment in concrete

Cited by 402 publications

References 8 publications

Anhydrite/aerogel composites for thermal insulation

Anhydrite/aerogel composites for thermal insulation

Köpük Betonun Reolojik Özelliklerinin Deneysel Olarak İncelenmesi

Use of Linear Alkylbenzene Sulfonate (Las) and Polycarboxylate-Ether (Pce) as Reagents in Iron Ore Flotation

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