Influence of Water-Reducing Admixtures on Properties of Cement Paste—A Miniature Slump Test

Wedding, PA; Kantro, D.L.

doi:10.1520/cca10190j

Cited by 335 publications

(39 citation statements)

References 2 publications

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“…The mini-slump test was used based on Kantro 1980, which allows the consistency of the fresh pastes to be compared between different formulations. The w/b ratio was set at 0.35 in the pastes and suitable percentages of polycarboxylate superplasticizer additive were added in order to maintain the consistency 94 ± 4 mm for all pastes.…”

Section: Composition and Preparation Of Cement Pastes And Mortarsmentioning

confidence: 99%

Effect of Partial Substitution of Highly Reactive Mineral Additions by Nanosilica in Cement Pastes

Rêgo

Frías

Moragues

et al. 2019

J. Mater. Civ. Eng.

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The phenomena involved in portland cement hydration and interactions with nanosilica are very complex and not yet fully understood. In addition, few papers have currently proposed to investigate the microstructure and mechanical properties of ternary mixtures using portland cement, colloidal nanosilica, and highly reactive mineral additions. This article investigates, for the first time, the behavior of different highly reactive mineral additions (silica fume and metakaolin) when partially replaced by colloidal nanosilica in the microstructure and hydration of cementitious materials. For the study of the cementitious material microstructures, a Langavant calorimeter, compressive strength, Xray diffraction, thermogravimetry, infrared spectroscopy, and mercury intrusion porosimetry were used. The pastes with a 1% substitution of highly reactive mineral additions by nanosilica showed higher compressive strength and more refined porosity than the pastes with only silica fume or metakaolin. The results show that nanosilica appears to have better synergism with metakaolin than with silica fume.

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Section: Composition and Preparation Of Cement Pastes And Mortarsmentioning

confidence: 99%

Effect of Partial Substitution of Highly Reactive Mineral Additions by Nanosilica in Cement Pastes

Rêgo

Frías

Moragues

et al. 2019

J. Mater. Civ. Eng.

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“…The slump test was carried out according to the method of Kantro (14). A miniature slump cone with the following dimensions was used: Top diameter 19 mm, bottom diameter 38 mm and height 57 mm.…”

Section: Methodsmentioning

confidence: 99%

Interacción entre cementos de diferente composición y aditivos superplastificantes

Ghorab

Kenawi

All³

2012

Mater. construcc.

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RESUMENSe ha estudiado el efecto fluidificante (hasta 90 minutos) ejercido por la incorporación de entre 0-1% de aditivos policondensados y policarboxilatos en pastas de cemento Portland, puzolánico, resistente a sulfatos y con adición de caliza.Con la incorporación de los aditivos policondensados, se produjo un incremento de la fluidez de los cementos Portland y puzolánico a mayores dosificaciones que las necesarias en los cementos resistente a sulfatos y con adición de caliza. Éste último presentó la mejor retención de la fluidez. Las fases aluminatos y sulfatos juegan un importante papel en la fluidez inducida.Todos los cementos incrementaron su fluidez con la incorporación de aditivos policarboxilatos a dosificaciones menores del 0,3%. El policarboxilato que no presenta en los espectros de RMN, resonancia asignada al protón de los grupos metil metileno, presenta buena retención de la fluidez. Esto es debido a la baja flexibilidad de la estructura y predominancia del efecto estérico. Este aditivo presenta también, mayor relación de grupos eter frente a grupos ester en los espectros IR, asi como una baja polidispersidad observada en la elución de especies de bajo peso molecular a través de HPLC.Palabras clave: cemento, superplastificantes, compatibilidad, fluidez, "minislump". SUMMARYThe slump behavior of ordinary Portland-, pozzolanic (red brick powder)-, sulfate resistant-, and limestone cement pastes caused by ≤1% additions of polycondensates and polycarboxylates superplasticizers are monitored for up to 90 minutes.With the plolycondensates, Portland-and pozzolanic cements gain fluidity at higher dosages than sulfate resistant and limestone cements. Limestone cement shows the best slump retention. The aluminate and sulfate phases play a major role in the fluidity.With the polycarboxylates, all cements gain fluidity with dosages of ≤0.3%. A polycarboxylate with no resonance of methyl methylene proton in the main chain identified in the NMR spectra creates good slump retention. This is explained by a low mobility of the structure and the predominance of the steric effect. The polycarboxylate shows also strong ether bands relative to the ester groups in the IR spectra and a low polydispersity observed in the elution of few low molecular weight species in the HPLC chromatogram.Keywords: cement, superplasticizers, compatibility, fluidity, minislump. Persona de contacto/Corresponding author: hanaa.ghorab@gmail.com INTRODUCCIÓNLos aditivos superplastificantes, también conocidos como reductores de agua de alto rango, que surgieron en los años sesenta del siglo pasado (1), son aditivos orgánicos cuya incorporación a los sistemas cementicios mejoran las propiedades mecánicas, permitiendo menores relaciones agua/cemento e incrementando su trabajabilidad. A lo largo del siglo XX-XXI se produjo la mejora progresiva de estos aditivos, que han llegado a ser componentes esenciales en la fabricación de hormigón de altas prestaciones. Los superplastificantes más empleados se basan en grupos sulfanados (de poli-ß-naftaleno y ...

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“…It was noted that even when the highest water and chemical admixture contents were used, it was not possible to perform the tests due to the lack of fluidity of the pastes. Figure 3 illustrates this situation, where no opening after the Kantro's miniature slump test 30 was verified, the diameter of the opening remaining the measurement of the cone itself. This is due to the fineness of SF and its high specific surface, requiring a chemical admixture content higher than 3% in order for the SF pastes to flow.…”

Section: Saturation Dosage Test Of the Chemical Admixturementioning

confidence: 99%

“…The results obtained in the Kantro's miniature slump test 30 and the Marsh's cone 31 are shown in Figure 2a and b, respectively.…”

Section: Saturation Dosage Test Of the Chemical Admixturementioning

confidence: 99%

Comparison of the Silica Fume Content for High-Strength Concrete Production: Chemical Analysis of the Pozzolanic Reaction and Physical Behavior by Particle Packing

2020

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Silica fume (SF) is the most commonly mineral admixture used for the production of high-strength concrete (HSC) due to its chemical characteristics of pozzolanic reactivity and physical filling effect. The objective of the present work is to compare the SF content by the chemical analysis of the pozzolanic reaction and the physical behavior by particle packing techniques. The first step of the study was to analyze the SF content to consume the calcium hydroxide (CH) produced during the hydration of Portland cement (PC), based on stoichiometric calculations. Then, the SF content for maximum packing density was obtained using analytical particle packing models and experimental tests. The compressive strength of the pastes was also measured. The results showed that the theoretical SF content for consuming CH is 15.6%, replacing PC. According to the packing density analytical models, the ideal SF content is 15% of the total fine materials. However, the experimental results indicated the use of a smaller SF content (10%). This difference between theoretical and experimental results is probably due to the high specific surface of the SF, which results in important surface forces between the grains, particle agglomeration and difficulty in SF densification with water.

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Influence of Water-Reducing Admixtures on Properties of Cement Paste—A Miniature Slump Test

Cited by 335 publications

References 2 publications

Effect of Partial Substitution of Highly Reactive Mineral Additions by Nanosilica in Cement Pastes

Effect of Partial Substitution of Highly Reactive Mineral Additions by Nanosilica in Cement Pastes

Interacción entre cementos de diferente composición y aditivos superplastificantes

Comparison of the Silica Fume Content for High-Strength Concrete Production: Chemical Analysis of the Pozzolanic Reaction and Physical Behavior by Particle Packing

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