Rheology, calorimetry and electrical conductivity related-properties for monitoring the dissolution and precipitation process of cement-fly ash mixtures

Fami, Nisrine El; Ez-zaki, Hassan; Sassi, O.; Boukhari, A.; Diouri, A.

doi:10.1016/j.powtec.2022.117937

Cited by 16 publications

(5 citation statements)

References 40 publications

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“…A shoulder peak also becomes evident within the time range of approximately 16 h to 22 h when the CCFA blending exceeds 10%. This observation may be the result of the early local pozzolanic reaction [56]. At 72 h, the cumulative heat release of samples was found to be nearly identical for the same mixture of CFA and CCFA.…”

Section: Hydration Performance Of Scmsmentioning

confidence: 80%

Investigating the Hydration, Mechanical Properties, and Pozzolanic Activity of Cement Paste Containing Co-Combustion Fly Ash

Ding,

Du,

et al. 2024

Buildings

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The heat of hydration, mechanical properties, pozzolanic activity, and microscopic characteristics of cement pastes incorporating co-combusted fly ash (CCFA) were investigated, and the disparities between the CCFA/cement system and the coal fly ash (CFA) binding system were also compared. The results indicate a decrease in the heat of hydration for both CFA and CCFA samples, with a more pronounced trend observed as the fly ash content increased from 10% to 30%. The distinction in the early hydration between CFA and CCFA samples primarily manifested in the rate of heat release, potentially correlated with variations in the active Al2O3 content in the fly ash. Neither CFA nor CCFA samples exhibited significant cementitious activity at 3 days, functioning solely as inert fillers in the cement paste. By 3 and 28 days, the mechanical properties of both CFA and CCFA samples were inferior to those of pure cement paste. However, by 180 days of hydration, the compressive strength of CCFA-blended mortar notably increased, with the highest strength observed in the 10% CCFA-blended sample. Both CFA and CCFA samples produced the secondary hydration product C-A-S-H and demonstrated comparable consumption of calcium hydroxide (CH). These findings underscore the potential of CCFA as a supplementary cementitious material (SCM) and lay a foundation for its widespread adoption.

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Section: Hydration Performance Of Scmsmentioning

confidence: 80%

Investigating the Hydration, Mechanical Properties, and Pozzolanic Activity of Cement Paste Containing Co-Combustion Fly Ash

Ding,

Du,

et al. 2024

Buildings

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“…This means that more water is distributed among the AFA particles and, correspondingly, less water interacts with the cement particles; in this way, hydration is prevented. As is pointed out in the literature [14,74], the rheological properties of pastes with different fineness of fly ash are highly related to the fly ash particle size. The mechanically activated fly ash can play a vital role in reducing the water requirement of normal consistency and decrease in setting time, due to the fineness of particles reducing the porosity in paste.…”

Section: Setting Timementioning

confidence: 94%

“…Additionally, incorporating fly ash in concrete lessens bleeding and segregation [13]. The addition of fly ash in the cement paste due to the dilution effect, which reduces the flocculation of particles and the lubricating effect of the smooth surface of fly ash particles, can improve the rheological properties of fresh paste [14]. Fly ash's pozzolanic reaction often takes longer than the hydration of cement [15,16].…”

Section: Introductionmentioning

confidence: 99%

The Effect of Mechanical Activation of Fly Ash on Cement-Based Materials Hydration and Hardened State Properties

et al. 2023

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Fly ash from coal represents the foremost waste product of fossil fuel combustion. These waste materials are most widely utilised in the cement and concrete industries, but the extent of their use is insufficient. This study investigated the physical, mineralogical, and morphological characteristics of non-treated and mechanically activated fly ash. The possibility of enhancing the hydration rate of the fresh cement paste by replacing part of the cement with non-treated and mechanically activated fly ash, and the hardened cement paste’s structure and early compressive strength performance, were evaluated. At the first stage of the study, up to 20% mass of cement was replaced by untreated and mechanically activated fly ash to understand the impact of the mechanical activation on the hydration course; rheological properties, such as spread and setting time; hydration products; mechanical properties; and microstructure of fresh and hardened cement paste. The results show that a higher amount of untreated fly ash significantly prolongs the cement hydration process, decreases hydration temperature, deteriorates the structure and decreases compressive strength. Mechanical activation caused the breakdown of large porous aggregates in fly ash, enhancing the physical properties and reactivity of fly ash particles. Due to increased fineness and pozzolanic activity by up to 15%, mechanically activated fly ash shortens the time of maximum exothermic temperature and increases this temperature by up to 16%. Due to nanosized particles and higher pozzolanic activity, mechanically activated fly ash facilitates a denser structure, improves the contact zone between the cement matrix, and increases compressive strength up to 30%.

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“…While Tambara Júnior 24 et al tested the rheological properties of the paste previously pre-sheared twice, and in the static and dynamic rheological tests, the shear rate was set to 0.05 s-1 and 100 s-1 was reduced to 0. Feng 25,26 et al used dynamic and static shear tests and small-amplitude oscillation to study the rheological properties and the recovery of inner structure in the cement-thickening agents paste. Fami 27 et al used the small amplitude oscillation method with a logarithmic amplitude of 0.001% to 100% and a frequency of 1 Hz to recover the cement-fly ash mortar after pre-shearing, and carried out a viscoelasticity test.…”

Section: Introductionmentioning

confidence: 99%

“…While Tambara Júnior 24 et al tested the rheological properties of the paste previously pre‐sheared twice, and in the static and dynamic rheological tests, the shear rate was set to 0.05 s‐1 and 100 s‐1 was reduced to 0. Feng 25,26 et al. used dynamic and static shear tests and small‐amplitude oscillation to study the rheological properties and the recovery of inner structure in the cement—thickening agents paste.…”

Section: Introductionmentioning

confidence: 99%

Effect of pre–shearing regimes on rheological parameters of cement paste

Feng,

Li,

et al. 2023

J Am Ceram Soc.

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In rheological testing, different test regimes can result in large differences in the rheological curves, and the pre‐shear procedure is one of the most important parts of the test. In order to investigate the effect of the pre‐shear regime on the rheological properties of cement pastes, an Anton Paar 102 rotary rheometer was used for the test. Two different pre‐shear regimes (RF and CP pre‐shear), three different pre‐shear duration times (50 s, 100 s, 150 s), and four different pre‐shear rates (25 s−1, 50 s−1, 100 s−1) are carried out for the test. The results showed that with the increase of pre‐shear duration or rate, the four rheological parameters (plastic viscosity, yield stress, rheological index, and thixotropy) of the pastes decrease in different degrees. RF pre‐shear was more influenced by shear time, while CP pre‐shear was influenced by shear time and rate. The pre‐shear regimes led to different changes in the flocculation structure of the cement paste, which had a great influence on rheological parameters ultimately. Based on the improved Krieger‐Dougherty model, the effective solid volume fraction of cement paste was calculated. Analysis shows that the phenomenon of “deflocculation” and “re‐flocculation” occurs when the cement paste is subjected to shear action, thus, the pre‐shear regimes destroy the structure of the pastes. With the increase of pre‐shear duration or rate, the effective volume fraction decreased, which indicated that the initial flocculation structure was broken. The greater the damage degree of pre‐shear, the slower the establishment rate of the internal structure of the pastes in dynamic shear, resulting in lower rheological parameters.

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Rheology, calorimetry and electrical conductivity related-properties for monitoring the dissolution and precipitation process of cement-fly ash mixtures

Cited by 16 publications

References 40 publications

Investigating the Hydration, Mechanical Properties, and Pozzolanic Activity of Cement Paste Containing Co-Combustion Fly Ash

Investigating the Hydration, Mechanical Properties, and Pozzolanic Activity of Cement Paste Containing Co-Combustion Fly Ash

The Effect of Mechanical Activation of Fly Ash on Cement-Based Materials Hydration and Hardened State Properties

Effect of pre–shearing regimes on rheological parameters of cement paste

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