Investigations on the influence of fly ash on the formation and stability of artificially entrained air voids in concrete

Spörel, Frank; Uebachs, Stephan; Brameshuber, Wolfgang

doi:10.1617/s11527-008-9380-z

Cited by 27 publications

(18 citation statements)

References 10 publications

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“…Within the O-series there is, however, a clear effect of the type of AEA since pre-blended (aged) AEA5 results in lower air entrainment compared to freshly blended AEA5. This is in accordance with Dodson [24] and Spörel [20], who noticed that the properties of AEAs change with age (especially synthetic) when conducting Foam index tests and who advised using solutions (AEAs) that are just a few days old. In connection to this, it is worth mentioning that admixture producers for economical reasons sell concentrated air-entraining agents to concrete producers to be diluted at the facility, but it has not been reported how the reduced performance of AEA with ageing is compensated and controlled.…”

Section: Effect Of Aea-sp Sequence Vs Effect Of Aea-dosagesupporting

confidence: 88%

“…Steinhoff [11] also confirmed difficulties in the application of FI test to verification of mutual performance of AEA and SP, and there was no more good correlation between the BET surface area of FA in concrete and FI, as other authors report [2,16,20,22]. Figure 3 shows the air entrainment in hardened concrete for two of the three matrix-volume series in Figure 2.…”

Section: Effect Of Aea-sp Sequence On Fresh Air Void Contentmentioning

confidence: 86%

“…Table 6 gives an overview of used methods and equipment during the testing. The prolonged mixing time of at least 2 minutes after the addition of AEA was chosen to assure full activation of surfactant [19] and reduced variability caused by fly ash [20]. We changed the mixing equipment from Hobart to Sandby mixer because of the unavailability of the first equipment and a need to increase the batch size for additional tests.…”

Section: Mixesmentioning

confidence: 99%

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Effect of AEA-SP Dosage Sequence on Air Entrainment in FA Concrete

Shpak

Jacobsen

2019

Nordic Concrete Research

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Laboratory measurements show that varying the dosage sequence of air-entraining agent and co-polymer in the mix (SP added before, after or together with AEA) greatly affects air entrainment in fresh and hardened fly ash concrete. Image analysis shows a somewhat lower specific surface when SP is added together with AEA. Foam Index measurements on the same binder materials, admixtures, and dosage sequences were therefore found less useful for studying the effect of admixture combinations. Obtaining a certain air content using the experience with AEA-SP dosage was found to be an untrivial task if there is a lack of parameter control. Finally, examples of successful mixing procedure for air entrainment in a series of high-volume fly ash concrete are shown.

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Section: Effect Of Aea-sp Sequence Vs Effect Of Aea-dosagesupporting

confidence: 88%

Section: Effect Of Aea-sp Sequence On Fresh Air Void Contentmentioning

confidence: 86%

Section: Mixesmentioning

confidence: 99%

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Effect of AEA-SP Dosage Sequence on Air Entrainment in FA Concrete

Shpak

Jacobsen

2019

Nordic Concrete Research

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“…The Since fresh concrete is a heterogeneous mixture with different phases, every constituent of the system affects the stability of air bubbles, and the corresponding mechanisms involved are complex. Generally, the factors affecting air bubble's stability in concrete include the properties of basic concrete components [33,34], the mix proportion of concrete [35][36][37], the mixing process [33,38], temperature [39], atmospheric pressure [20,40], air-entraining agents [41][42][43], other chemical additives [44][45][46], mineral admixtures [47][48][49][50], and the quality of mixing water [15]. Each constituent of the system, either internal or external, influences bubble stability to a varying extent.…”

Section: Formation Of Bubbles In Concretementioning

confidence: 99%

A Review on Bubble Stability in Fresh Concrete: Mechanisms and Main Factors

et al. 2020

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In order to improve the stability of air bubbles in fresh concrete, it is of great significance to have a better understanding of the mechanisms and main influencing factors of bubble stability. In the present review, the formation and collapse process of air bubbles in fresh concrete are essentially detailed; and the advances of major influencing factors of bubble stability are summarized. The results show that the surface tension of air–liquid interface exerts a huge impact on bubble stability by reducing surface free energy and Plateau drainage, as well as increasing the Gibbs surface elasticity. However, surface tension may not be the only determinant of bubble stability. Both the strength of bubble film and the diffusion rate of air through the membrane may also dominate bubble stability. The application of nano-silica is a current trend and plays a key role in ameliorating bubble stability. The foam stability could be increased by 6 times when the mass fraction of nano-particle reached 1.5%.

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“…3). The average CCP reuse rates for 15 different reuse categories between 2002 and 2009 in the U.S. (ACAA, 2011), demonstrate that the most common application for fly ash reuse was as raw material for cement production and as a pozzolanic component in various concrete products (Ahmaruzzaman, 2010;Ganesan et al, 2007;Gao et al, 1997;Hall and Livingston, 2002;Hill et al, 1997;Kulaots et al, 2003;Pedersen et al, 2008;Sporel et al, 2009;Wang and Baxter, 2007) (Fig. 4).…”

Section: Coal Combustion Productsmentioning

confidence: 99%

Geological disposal of energy-related waste

Yeboah

Burns

2011

KSCE J Civ Eng

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The production of waste materials during energy recovery processes is an unavoidable consequence of the need for energy; consequently, safe and efficient disposal or reuse alternatives for these waste materials is essential for sustainable development. For waste streams that must be geologically disposed, the largest volumes of energy related waste include Coal Combustion Products (CCPs) such as fly ash, coal mining wastes, and processed water and drill cuttings from oil and gas exploration, with relatively small amounts of silica resulting from pipe scaling in geothermal energy production. The fate of the vast majority of these energy-related wastes is geologic disposal, which ranges from placement in landfills (lined or unlined) or surface impoundments, to deep injection within geologic units. Applications for productive reuse of energy-related wastes are cost effective alternatives to disposal, and are gaining popularity as sustainability of processing becomes more critical. This review paper examines geologic disposal and reuse of energy-related waste streams within the U.S., and provides insight into fuel-to-waste production ratios, preferred disposal or productive reuse alternatives, and associated geotechnical/environmental considerations.

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Investigations on the influence of fly ash on the formation and stability of artificially entrained air voids in concrete

Cited by 27 publications

References 10 publications

Effect of AEA-SP Dosage Sequence on Air Entrainment in FA Concrete

Effect of AEA-SP Dosage Sequence on Air Entrainment in FA Concrete

A Review on Bubble Stability in Fresh Concrete: Mechanisms and Main Factors

Geological disposal of energy-related waste

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