Correlations of the dispersing capability of NSF and PCE types of superplasticizer and their impacts on cement hydration with the adsorption in fresh cement pastes

Zhang, Yanrong; Kong, Xiangming

doi:10.1016/j.cemconres.2014.11.009

Cited by 299 publications

(102 citation statements)

References 30 publications

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“…Seventy per cent less PCE than BNS was adsorbed by CEM I (plateau values = 5.99 and 19.40 mg polymer/g cement, respectively). These results are consistent with earlier findings, according to which cement adsorbed BNS and PMS (melanin derivative) admixtures more readily than polycarboxylate ether-based superplasticisers (11,42,43).…”

Section: Adsoption Isotherms For Cem I and Sands In Watersupporting

confidence: 83%

PCE and BNS admixture adsorption in sands with different composition and particle size distribution

et al. 2017

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ABSTRACT:The choice of a superplasticiser (SP) for concrete is of great complexity, as it is well known that properties of the end product are related to admixture and its compatibility with concrete components. Very few studies have been conducted on the compatibility between SPs and the sand of mortars and concretes, however. Practical experience has shown that sand fineness and mineralogical composition affect water demand and admixture consumption. Clay-containing sand has been found also to adsorb SPs, reducing the amount available in solution for adsorption by the cement. This study analysed the isotherms for PCE and BNS superplasticiser adsorption on four sands with different fineness and compositions commonly used to prepare mortars and concretes. BNS-based SP did not adsorb on sands, while PCE-based admixtures exhibited variable adsorption depending on different factors. The adsorption curves obtained revealed that the higher the sand fineness, the finer the particle size distribution and the higher the clay material, the greater was PCE admixture adsorption/ consumption. RESUMEN: Adsorción de aditivos PCE y BNS en arenas con diferente composición y distribución de tamaño departículas. La elección de un superplastificante (SP) para el hormigón es un proceso complejo, ya que las propiedades del producto final se relacionan con la naturaleza del aditivo y su compatibilidad con los componentes del hormigón. Sin embargo hay pocos estudios sobre la compatibilidad entre los SPs y arenas utilizadas en morteros y hormigones. En la práctica se ha demostrado que la finura y la composición mineralógica de la arena afectan a la demanda de agua y al consumo de SPs. Las arcillas que pueden encontrarse en las arenas pueden también adsorber aditivos, reduciendo la cantidad disponible en solución para la adsorción por el cemento. Se han analizado las isotermas de adsorción para SPs de tipo PCE y BNS en cuatro arenas de diferente finura y composicion comúnmente utilizado para preparar morteros y hormigones. El aditivo BNS no se adsorbe en las arenas, mientras que los PCE mostraron adsorción variable. Las curvas de adsorción revelaron que cuanto mayor es la finura de arena, menor la distribución del tamaño de partícula y mayor el contenido de arcilla mayor era adsorción/intercalación de aditivos PCE en las arenas.

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Section: Adsoption Isotherms For Cem I and Sands In Watersupporting

confidence: 83%

PCE and BNS admixture adsorption in sands with different composition and particle size distribution

et al. 2017

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“…The adsorption amount of PCE has been reported to determine the dispersion ability of PCE [26]. In the presence of retarder, competitive adsorption would happen between PCE and retarder; it meant that the adsorption process of PCE would be hindered by the addition of phosphate, which resulted in a decline in the dispersion [20,31,54].…”

Section: Adsorption Amountmentioning

confidence: 99%

“…These results were expected to be useful for the design of highly efficient dispersants. dispersion capacity [26][27][28][29][30]. Based on this, the retarder might hinder the adsorption process of PCE and it was referred to as competitive adsorption [31][32][33][34][35], thereby reducing the dispersion.…”

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confidence: 99%

Effect of Sodium Hexametaphosphate and Trisodium Phosphate on Dispersion of Polycarboxylate Superplasticizer

Zhang

Liu

et al. 2019

Materials

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Enhancement in dispersion of polycarboxylate superplasticizer (PCE) could be obtained by incorporating retarders in normal concrete. The generally believed reason was that the consumption of free water and polymer at the beginning was reduced by retarding cement hydration. This theory could not convincingly explain why sodium hexametaphosphate (SHMP) was able to promote the dispersion capacity of PCE, while trisodium phosphate (TSP) could not, despite that both TSP and SHMP could obviously retard the cement hydration. The adsorption behavior of PCE and phosphate was investigated and the mechanism was analyzed in order to gain deeper understanding. The results showed that TSP and SHMP delayed the cement hydration, impeded adsorption process of PCE, and increased thickness of adsorption layer. It was interesting that TSP reduced the dispersion, but SHMP enhanced. The reason for this contradiction was due to the difference in composition of adsorption layer. In the PCE-TSP system, this layer was composed of the precipitates (formed by TSP and Ca 2+ ) and the invalided PCE (caused by these precipitates in the immediate vicinity of the cement grains); the invalided PCE was due to the decrease of PCE dispersion. In the PCE-SHMP system, "Inner-phosphate (multi-layers) + Outer-PCE (single layer)" structure was formed to make the PCE work more effective, hence enhancing the dispersion. These results were expected to be useful for the design of highly efficient dispersants. dispersion capacity [26][27][28][29][30]. Based on this, the retarder might hinder the adsorption process of PCE and it was referred to as competitive adsorption [31][32][33][34][35], thereby reducing the dispersion. In addition, the thickness of the adsorption layer should also be accepted as a factor influencing the dispersion of PCE [36,37]. In spite of the decline in adsorption amount of PCE in the presence of retarder, as reported in previous study, the adsorption layer was obviously thickened to enhance the dispersion [37]. On the basis of discussion above, the conclusion could be made that the dispersion capacity of the PCE-retarder system should be associated with the retarding effect of retarder, adsorption behavior of PCE, and the thickness of the adsorption layer.Poly-phosphates, such as sodium tripolyphosphate and sodium hexametaphosphate (SHMP), have been widely used to promote the dispersion ability and dispersion retention ability of the superplasticizer system in real engineering practice. However, mono-phosphates, such as trisodium phosphate (TSP) and sodium hydrogen phosphate, cannot play the same roles as poly-phosphate in commercially available PCE products. If the retardation was the main reason for the enhancement, poly-phosphate and mono-phosphate would both have a similar effect on dispersion of PCE system, because both TPS and SHMP could retard the cement hydration [38]. Therefore, the reason why the poly-phosphate could effectively enhance the dispersion, whilst the mono-phosphate failed cannot be simply explained by the retard...

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“…The reason why superplasticizer can retard the demulsification process of asphalt emulsion in CA mortar may be due to its effect on cement. Superplasticizer can prevent cement particles from flocculation and have retarding effect on cement hydration[29], thus it slows down the structure rebuild rate of CA paste[18]. Because of the two effects, superplasticizer slows down the demulsifying rate of asphalt emulsion in CA mortar.…”

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confidence: 99%

The role and interaction of superplasticizer and emulsifier in fresh cement asphalt emulsion paste through rheology study

Ouyang

Han

Cao

et al. 2016

Construction and Building Materials

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The workability and mechanical properties of cement asphalt emulsion (CA) mortar are unstable due to the complex interaction between cement and asphalt emulsion. To reveal the interaction between cement and asphalt emulsion, the effect of emulsifier and superplasticizer on the rheology of cement paste and asphalt emulsion is investigated, respectively, and the effect of the interaction between emulsifier and superplasticizer on the rheology of cement paste is studied in this paper as well. Results show that the apparent viscosity and yield stress of asphalt emulsion increase with superplasticizer and emulsifier dosage. Emulsifier can change the yield stress and apparent viscosity of cement paste, and its effect on cement paste differs greatly with the type and dosage of emulsifier. Some emulsifiers can increase the yield stress of cement paste, but some emulsifiers can decrease the yield stress of cement paste. Emulsifier has interaction with superplasticizer, thus affecting the reducing water effect of superplasticizer on cement paste. There is a competition relationship between emulsifier and superplasticizer when they are adsorbed by cement particles. The mixing method, in which superplasticizer is mixed with cement before emulsifier added, is beneficial to obtain a lower apparent viscosity of cement paste for all tested emulsifiers.

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Correlations of the dispersing capability of NSF and PCE types of superplasticizer and their impacts on cement hydration with the adsorption in fresh cement pastes

Cited by 299 publications

References 30 publications

PCE and BNS admixture adsorption in sands with different composition and particle size distribution

PCE and BNS admixture adsorption in sands with different composition and particle size distribution

Effect of Sodium Hexametaphosphate and Trisodium Phosphate on Dispersion of Polycarboxylate Superplasticizer

The role and interaction of superplasticizer and emulsifier in fresh cement asphalt emulsion paste through rheology study

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