Adsorption characteristics of superplasticizers on cement component minerals

Yoshioka, Kazuhiro; Tazawa, Ei-ichi; Kawai, Kenji; Enohata, Tomoyuki

doi:10.1016/s0008-8846(02)00782-2

Cited by 433 publications

(186 citation statements)

References 5 publications

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“…In the slag-free cement pastes (cement C1), the C 3 A content able to adsorb admixture [29] and also able to consume it to form an organic-mineral phase is higher [12,30]. Consequently, if a high proportion of PCs is adsorbed and consumed by C 3 A, there could be less admixture available in aqueous phase for dispersing the cement grains by adsorption onto their surface [12,21].…”

Section: Rheological Behaviourmentioning

confidence: 99%

Effect of PCs superplasticizers on the rheological properties and hydration process of slag-blended cement pastes

et al. 2009

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The effect of polycarboxylate (PC) superplasticizers with different structure on the rheological properties and hydration process of slag-blended cement pastes with a slag content between 0 and 75% has been studied. Fluidizing properties of PCs admixtures are significantly higher in slag-blended cement with respect to non-blended Portland cement. Also, it has been observed that the rise of the fluidity induced by the PCs on the cement pastes increases with the slag content. This effect is mainly attributed to a decrease in the amount of C 3 A available to adsorb and consume admixture to form an organo-mineral phase. Consequently, the PC admixtures are absorbed onto the silicate phases of the clinker and onto the slag particles, inducing a repulsion and the concomitant reduction in yield stress despite a reduction in the zeta potential. The rheological results allow us to conclude that the highest increase of the fluidity is caused by the admixtures with highest molecular weight due to the higher steric repulsion induced. As a consequence of the adsorption of the PCs, a delay of the hydration process of the pastes has been observed.

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Section: Rheological Behaviourmentioning

confidence: 99%

Effect of PCs superplasticizers on the rheological properties and hydration process of slag-blended cement pastes

et al. 2009

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“…In the resulting dispersion, the water retained in the flocs is released, enhancing flowability. Other authors have described the factors affecting the fluidizing effect of superplasticizer admixtures, concluding that it depends not only on the type of admixture used, but also on factors associated with the cement itself, such as C 3 A content, type and content of calcium sulphate used as a setting regulator [11][12][13], alkalis content [14], specific surface and particle size distribution [9,15] and type of mineral additions [10,16].…”

Section: Introductionmentioning

confidence: 99%

Adsorption of superplasticizer admixtures on alkali-activated slag pastes

Palacios

Houst

Bowen

et al. 2009

Cement and Concrete Research

173

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Alkali-activated slag (AAS) binders are obtained by a manufacturing process less energy-intensive than ordinary Portland cement (OPC) and involves lower greenhouse gasses emission. These alkaline cements allow the production of high mechanical strength and durable concretes. In the present work, the adsorption of different superplasticizer admixtures (naphthalene-based, melamine-based and a vinyl copolymer) on the slag particles in AAS pastes using alkaline solutions with different pH values have been studied in detail. The effect of the superplasticizers on the yield stress and plastic viscosity of the AAS and OPC pastes have been also evaluated. The results obtained allowed us to conclude that the adsorption of the superplasticizers on AAS pastes is independent of the pH of the alkaline solutions used and lower than on OPC pastes. However, the effect of the admixtures on the rheological parameters depends directly on the type and dosage of the superplasticizer as well as of the binder used and, in the case of the AAS, on the pH of the alkaline activator solution. In 11.7-pH NaOH-AAS pastes the dosages of the superplasticizers required to attain similar reduction in the yield stress are ten-fold lower than for Portland cement. In this case the superplasticizers studied show a fluidizing effect considerably higher in 11.7-pH NaOH-AAS pastes than in OPC pastes. In 13.6-pH NaOH-AAS pastes, the only admixture observed to affect the rheological parameters is the naphthalene-based admixture due to its higher chemical stability in such extremely alkaline media.

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“…Above a 0.5% dosage, the cement particle surfaces were fully covered with MA polymer molecules, and with multilayer adsorption, the x-potential of the cement particle surfaces does not increase with MA polymer dosage. 22 Figure 2 also indicates that the functional groups bonded to the MA polymers have an effect on the water-reduction percentage. The SPF polymer at 0.5% dosage showed 18.3% water reduction, whereas the percentage of water reduction for the AS and AH polymers at same dosage was 28.5% and 32.2%, respectively.…”

Section: Resultsmentioning

confidence: 94%

Effect of the molecular structure of monocyclic aromatic polymer on the application properties of concrete

Zhao

Deng

Tang

2011

Polym J

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New water-soluble monocyclic aromatic (MA) polymers, including sulfonated phenol-formaldehyde polymer (SPF), aminosulfonate-phenol-formaldehyde polymer (AS) and aminosulfonate-phenol-salicylic acid-formaldehyde polymer (AH), were synthesized. The molecular structure of the MA polymers was characterized by gel permeation chromatography and infrared spectroscopy. The application properties of the MA polymers in concrete were also evaluated. The test results showed that the MA polymers have approximately the same molecular weight. The molecular structure of the SPF polymer was observed to have more -SO 3 and fewer -OH groups than the other polymers and exhibits a high percentage of water-reduction percentage, high slump loss and poor workability-preservation properties. The molecular structure of the AS and AH polymers features -SO 3 and -COOH as dispersion groups, and ÀOH and -NH 2 as fluidity preservation groups, such that they exhibit better water-reducing capacity, workability-preservation properties, retardation of the setting time for cement paste and higher compressive strengths for concrete than the SPF polymer at the same curing time and dosage.

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Adsorption characteristics of superplasticizers on cement component minerals

Cited by 433 publications

References 5 publications

Effect of PCs superplasticizers on the rheological properties and hydration process of slag-blended cement pastes

Effect of PCs superplasticizers on the rheological properties and hydration process of slag-blended cement pastes

Adsorption of superplasticizer admixtures on alkali-activated slag pastes

Effect of the molecular structure of monocyclic aromatic polymer on the application properties of concrete

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