Role of Steric Hindrance in the Performance of Superplasticizers for Concrete

Yoshioka, Kazuhiro; Sakai, Etsuo; Daimon, Masaki; Kitahara, Ayao

doi:10.1111/j.1151-2916.1997.tb03169.x

Cited by 280 publications

(140 citation statements)

References 6 publications

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“…In a later paper Gartner et al also conclude to the predominance of steric hindrance [24]. It is only more recently with the development of new generation superplasticizers which contain side chains of polyalkylene oxide, that the possibility of steric stabilisation has become a widely acknowledged mechanism [25,26]. These polymers are also referred to as comb-type copolymers, referring to the adsorption conformation that they are supposed to adopt at the surface of cement particles.…”

Section: Individual Forcesmentioning

confidence: 98%

Towards a prediction of superplasticized concrete rheology

Flatt¹

2004

Mat. Struct.

129

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The rheology of concrete is influenced by water content, the amount, size and size distribution of all the solid components as well as by the dispersion of the finer particles through the addition of superplasticizers. In addition, the rheological behaviour over time evolves as a result of cement hydration. Consequently the a-priori prediction of concrete rheology is a complex task.In this article, models that have been and are being developed to achieve this task are discussed. The key role of the degree of dispersion will be underlined. A treatment of interparticle forces and a yield stress model integrating these will be presented. Such work is necessary to integrate the dispersion efficiency of superplasticizers based on their dosage and molecular structures into existing models for predicting concrete rheology. RESUMI~

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Section: Individual Forcesmentioning

confidence: 98%

Towards a prediction of superplasticized concrete rheology

Flatt¹

2004

Mat. Struct.

129

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“…(1). The number average molecular weight of methoxypolyethyleneglycol (MPEG) side chains and the composition of PCE have been estimated classically by 1 H-NMR spectroscopy. The molecular weight of PCE was determined using a Wyatt Technology miniDAWN μ static three-angle laser light scattering detector (MALLS) equipped with TSK-GELSW (TOSOH) columns.…”

Section: Comb-like Copolymer Dispersantsmentioning

confidence: 99%

Effects of Grafting Densities of Comb-Like Copolymer on the Dispersion Properties of Concentrated Cement Suspensions

Liu¹,

Ran

Miao³

et al. 2012

Mater. Trans.

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Effects of grafting densities of comb-like copolymer on the dispersion properties of concentrated cement suspensions are investigated systemicly in this paper. For comb-like copolymers the adsorbed amount increases at the same dosages as the grafting density decreases, while the efficiency of dispersion is improved by increasing the grafting densities. Based on the theory of Flatt at level of scaling law, the molecule size and the occupied surface area of the comb-like polymers with different grafting densities are calculated. The comb-like polymers with higher grafting density has bigger molecular size. For comb-like polymer dispersant, the steric repulsion provided by the side chains is the main drive of the dispersion, so the Flory energy is employed to explore the relationship between steric repulsion and grafting density. The calculation tells us that higher grafting density results in higher Flory energy which represents stronger steric repulsion. The calculation method based on the scaling law and Flory theory is successfully used to interpret the dispersion mechanism, and it is anticipated that this method can be applied to explain the effect of other parameters of PCE comb-like polymers on the dispersion properties of cement suspensions, ceramics suspensions, slurries and so on.

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“…When the polymers are stably adsorbed on the surface of particles, steric hindrance (V steric ) should be taken into account. The total interaction potential energy (V EDLVO ) between particles is given as follows [28]:…”

Section: Comparison Of Experimental Results With Theorymentioning

confidence: 99%

Preparation of stable aqueous suspensions of antimony-doped tin oxide nanoparticles used for transparent and thermal insulation fluorocarbon coating

Tan

Liao

et al. 2014

Colloid Polym Sci

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In order to prepare the highly stable aqueous suspensions of antimony-doped tin oxide (ATO) used for the transparent and thermal insulation fluorocarbon coating, the effect of sodium polyacrylate (PAAS) and polyvinyl alcohol (PVA) on the stability of the suspensions was investigated. The stability and dispersity of the suspensions were characterized using zeta potential analyzer, ultravioletvisible spectrophotometer, and scanning electron microscope. No sediments were observed after 6-month storage of the ATO suspensions containing 0.1 wt% PAAS and 2.0 wt% PVA. The reason why aqueous suspensions were capable of stabilization was explained from a theoretical perspective. A new model of steric hindrance for colloid particles stabilized by binary dispersant was proposed, which may have positive contribution to other colloid system containing two dispersants. A nanocomposite fluorocarbon coating, exhibiting a good thermal insulation and high transmittance, was formed after ATO suspensions were added in fluorocarbon emulsion.The temperature inside the chamber was decreased by 6.0°C, and 75.0 % visible light rays could pass through the coating.

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Role of Steric Hindrance in the Performance of Superplasticizers for Concrete

Cited by 280 publications

References 6 publications

Towards a prediction of superplasticized concrete rheology

Towards a prediction of superplasticized concrete rheology

Effects of Grafting Densities of Comb-Like Copolymer on the Dispersion Properties of Concentrated Cement Suspensions

Preparation of stable aqueous suspensions of antimony-doped tin oxide nanoparticles used for transparent and thermal insulation fluorocarbon coating

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