A review of the mechanisms of set-retardation in portland cement pastes containing organic admixtures

Young, J. F.

doi:10.1016/0008-8846(72)90057-9

Cited by 300 publications

(117 citation statements)

References 23 publications

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“…The general aim of these applications is improving material properties, e.g. workability, setting time, water requirement and mechanical strength (Aitcin and Neville 2003;Jansen et al 2012;Young 1972), consequently producing high-strength and high-performance concretes (Jansen et al 2012;Li et al 2005;Neville and Aitcin 1998). The influence of admixed polymers on the properties of cement-based materials is reported to be mainly related to their dispersion ability via increasing repulsive forces and hindering the coagulation and sedimentation of the cement particles by introducing electrostatic and/or steric repulsion (Jansen et al 2012;Mollah et al 2000).…”

Section: Introductionmentioning

confidence: 99%

“…The reported mechanisms are generally commented with regard to the molecular structure and adsorption characteristics of the investigated polymeric additions (Uchikawa et al 1997). It is also known that admixed polymers generally influence cement hydration to a significant extent, consequently affect the morphology and microstructure of cement-based materials (Chandra and Flodin 1987;Mollah et al 2000;Young 1972). …”

Section: Introductionmentioning

confidence: 99%

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Early Age Hydration, Microstructure and Micromechanical Properties of Cement Paste Modified with Polymeric Vesicles

Koleva

et al. 2013

ACT

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The influence of limited concentration, of 0.025 wt.% per cement weight, poly (ethylene oxide) -block -polystyrene vesicles on the hydration process, microstructure and micromechanical properties of cement paste at early hydration age of maximum 7 days are discussed. Isothermal calorimetry and non-evaporable water content tests indicate that the admixed vesicles have no apparent influence on the process of cement hydration, but affect microstructural properties. Whereas nitrogen adsorption tests reveal that the gel pore structure of the vesicles-modified matrix is almost identical to the vesicles-free one, mercury intrusion porosimetry proves refined capillary porosity and reduced total porosity in the presence of admixed vesicles. Nano-indentation supports the above observations and indicates that the admixed vesicles act as nucleation sites, leading to a more uniform distribution of low density hydration products.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Early Age Hydration, Microstructure and Micromechanical Properties of Cement Paste Modified with Polymeric Vesicles

Koleva

et al. 2013

ACT

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“…They show some influence on the habit of CH grown slowly by interdif fusion of the ions (55 Figure 15) . Young (32) pointed out, there is no correlation between the stability constants of the calcium complexes of these substances and their potency as a retarder.…”

Section: Reduction Of Datamentioning

confidence: 99%

“…Young (32) has also suggested that the attachment could be via some complex between surface atoms and the retarder molecules.…”

Section: Reduction Of Datamentioning

confidence: 99%

Retarders for Concrete and Their Effects on Setting Time and Shrinkage : Interim Report

Yamamoto¹

1972

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Sixty-five pure chemicals and three proprietary retarders were tested in the penetration test for setting time at concentrations at or around 0.1% of the cement. The most effective retarders had several, closely-grouped oxygen atoms in hydroxyl, carboxyl , or carbonyl groups.Some of the retarders were used in the fabrication of 0.2 x 0.2 x 4-in. bars of cement paste, which were subsequently oven-dried and the shrinkage, non-evaporable water content, and specific surface of the paste was determined. The retarders caused a change in the shrinkage that was paralleled by a change in the specific surface of the paste.The contents do not necessarily reflect the official views or policies of the Federal Highway Administration. This report does not constitute a standard, specification, or regulation. Determinations of specific surface area, non-evaporable and evaporable water contents, and scanning electron microscopic observation were made on cement paste samples to explore whether or not some changes were induced in the cement hydrates by the addition of retarders.The following are main findings in this research.

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“…The retardation of cement hydration using organic materials is well reported (Wilding et al, 1984;Young, 1972). Far less information about the use of inorganic compounds exists; the majority of work has focused on lead (Pb 2+ ), tin (Sn 2+ and Sn 4+ ), zinc (Zn 2+ ), borate (BO 3 3-) and phosphate (PO 4 3-) (Bénard et al, 2005(Bénard et al, , 2008Ltifi et al, 2011;Ma and Brown, 1994;Odler, 2004;Taylor, 1997).…”

Section: Introductionmentioning

confidence: 99%

Deep borehole disposal grouts – are inorganic retarders appropriate?

Collier

Pawar

Milestone

et al. 2018

Advances in Cement Research

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Cementitious grouts are being developed for use as sealing and support matrices (SSMs) in deep borehole disposal (DBD) of high-level radioactive waste. These SSMs will seal the waste containers within a disposal zone and provide physical support during package placement. The ambient temperature and pressure will be 80-130°C and 30-50 MPa, respectively, depending on depth and local geological conditions. This will accelerate grout thickening, so retardation is required to facilitate slurry placement. Certain inorganic materials suppress cement hydration and retard thickening under ambient conditions. However, their retardation characteristics are unknown at elevated temperature and pressure. Inorganic compounds of borate, phosphate, tin and zinc were investigated as retarders, and a summary of the work is provided in this paper. All retarders were found to delay thickening, with only borate providing sufficient retardation, but only at 90°C (0·75% addition); retardation was nearly sufficient at 120°C (1% addition). The effect of all the retarders on wet paste properties was not consistent but, generally, plastic viscosity and yield stress peaked at specific addition levels. None of the retarders influenced phase composition, and each retarding ion was evenly distributed throughout the hardened microstructure. The results of this study led to the conclusion that no inorganic retarder is appropriate for use across the whole DBD temperature range.

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A review of the mechanisms of set-retardation in portland cement pastes containing organic admixtures

Cited by 300 publications

References 23 publications

Early Age Hydration, Microstructure and Micromechanical Properties of Cement Paste Modified with Polymeric Vesicles

Early Age Hydration, Microstructure and Micromechanical Properties of Cement Paste Modified with Polymeric Vesicles

Retarders for Concrete and Their Effects on Setting Time and Shrinkage : Interim Report

Deep borehole disposal grouts – are inorganic retarders appropriate?

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