A new insight into the working mechanism of PCE emphasizing the interaction between PCE and Ca2+ in fresh cement paste

Tian, Hongwei; Kong, Xiangming; Miao, Xiaowei; Jiang, Lin; Pang, Xiaofan

doi:10.1016/j.conbuildmat.2020.122133

Cited by 22 publications

(3 citation statements)

References 39 publications

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“…When AH 3 complexes with PCE and the complex adsorbs on the surface of AH 3 , repulsion occurs between adjacent AH 3 particles, which improves the dispersion properties. 32 When the PCE content in AH 3 -PCE is high (P6), complexation of one PCE molecule may occur with multiple AH 3 molecules 37,38 leading to an increase in particle size. In general, the particle size of AH 3 -PCE ultrafine composites was affected by PCE content.…”

Section: Role Of Ah 3 -Pce Ultrafinementioning

confidence: 99%

Effect of AH₃-PCE Ultrafine Composites on the Properties of Sulfoaluminate Cement-Based Materials

Li,

Hu,

et al. 2023

ACS Appl. Nano Mater.

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The use of superfine particles has been found to be a promising method for accelerating cement hydration. Amorphous aluminum hydroxide (AH3) is a key hydration product in sulfoaluminate cements and our preliminary research work indicated that the ultrafine amorphous AH3 accelerates the hydration rate of sulfoaluminate cement-based grouting materials (SAGMs). However, the ultrafine AH3 tends to agglomerate easily, which affects its effectiveness. In this study, aluminum hydroxide-polycarboxylic acid superplasticizer (AH3-PCE) ultrafine composites were prepared using the sol–gel method, and their effect on the hydration and hardening process of SAGMs was investigated. The results showed that the particle size of the AH3-PCE ultrafine composites decreased and then increased with increasing amount of PCE and there was a strong interaction of AH3 with PCE through the oxygen atoms of C–O–C. AH3-PCE ultrafine composites provided nucleation for the growth of bayerite and ettringite (AFt). Moreover, the AH3-PCE ultrafine composites released aluminum ions and PCE in an alkaline solution at pH 12.5. The AH3-PCE ultrafine composites promoted cement hydration, adjusted the pore structure of the hardened paste, and improved the compressive strength at all ages owing to the synergistic effect of nucleation, aluminum ions, and PCE released from the AH3-PCE ultrafine composite.

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Section: Role Of Ah 3 -Pce Ultrafinementioning

confidence: 99%

Effect of AH₃-PCE Ultrafine Composites on the Properties of Sulfoaluminate Cement-Based Materials

Li,

Hu,

et al. 2023

ACS Appl. Nano Mater.

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“…Initially, PCE will attach to the surface of C 3 A and C 4 AF, then rapidly attach to surfaces of early hydration products, such as the alumina/ferric oxide mono/tri-sulfate phase [78,80]. By incorporating sulfonic groups, the binding capacity with Ca(II) will be reduced [81]. The adsorption on negatively charged particles is greatly reduced.…”

Section: Other Effectsmentioning

confidence: 99%

Advances in Organic Rheology-Modifiers (Chemical Admixtures) and Their Effects on the Rheological Properties of Cement-Based Materials

et al. 2022

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Organic rheology modifiers, especially superplasticizers and viscosity-modifying admixtures (VMAs), have become key components for the workability optimization of modern concrete. The development of these admixtures is crucial to the further performance improvement of modern concrete under different casting and service conditions. Many of the former reviews have summarized research advances in respect of these admixtures from chemical and material perspectives, focusing on the effects of structure and the performance. In this paper, from a rheological perspective, an overview is provided of the microscale behavior of polycarboxylate (PCE) superplasticizers and VMAs (e.g., adsorption, conformation, and bridging) in terms of the evolution of the microstructure of the paste, the effect of chemical structure on the yield stress, the apparent viscosity and thixotropy of cement-based materials, and the structure design of these admixtures. Most importantly, in addition to a general discussion with assumptions (monolayer adsorption of a “flat” conformation, with each molecule on a single particle; statistical polymer composition), special conditions (e.g., preferential adsorption, depletion effects, hydration modification effects, and the polydispersity of the polymer composition) are discussed. Newly developed admixtures, realized through regulation of the microscale behavior, and by the modification of adsorption, topological structure, and molecular frame, are introduced.

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“…In addition, the depletion force generated by non‐absorbed polymers would contribute to the formation of flocculants if the distance is close enough 16,24 . These non‐absorbed PCE polymers may interact with ions by the complexation, which may change the morphology or conformation (i.e., size) of the polymers and possibly lead to impacts on rheology over time 25,26 . However, in practice, the above mechanisms are not easily identified due to many factors (i.e., hydrate formation, ions released from cement, and water consumption), which change with the hydration process over time, etc.…”

Section: Introductionmentioning

confidence: 99%

Effect of resting time on rheological properties of glass bead suspensions: Depletion and bridging force among particles

Ji,

Becker,

et al. 2023

J Am Ceram Soc.

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Effect of resting time on rheological properties of cement suspension is generally explained by early formed structure and overconsumption of PCE superplasticizers. In this paper, we propose that the influence of resting time on the rheological properties is closely related to size variation of non‐absorbed PCE. To identify this, glass beads suspensions were prepared with various amounts of PCE and ionic solution, and their rheological properties were evaluated at various times. We found that the yield stress increases with time at higher PCE concentrations and higher ionic strength solutions. Adsorbed PCE during resting tends to bridge the particles rather than disperse them. In addition, it was found that hydrodynamic radius of PCE increased with resting time, and depletion forces resulting from non‐absorbed PCE size change correlate well with the increased yield stress.This article is protected by copyright. All rights reserved

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A new insight into the working mechanism of PCE emphasizing the interaction between PCE and Ca2+ in fresh cement paste

Cited by 22 publications

References 39 publications

Effect of AH₃-PCE Ultrafine Composites on the Properties of Sulfoaluminate Cement-Based Materials

Effect of AH₃-PCE Ultrafine Composites on the Properties of Sulfoaluminate Cement-Based Materials

Advances in Organic Rheology-Modifiers (Chemical Admixtures) and Their Effects on the Rheological Properties of Cement-Based Materials

Effect of resting time on rheological properties of glass bead suspensions: Depletion and bridging force among particles

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A new insight into the working mechanism of PCE emphasizing the interaction between PCE and Ca2+ in fresh cement paste

Cited by 22 publications

References 39 publications

Effect of AH3-PCE Ultrafine Composites on the Properties of Sulfoaluminate Cement-Based Materials

Effect of AH3-PCE Ultrafine Composites on the Properties of Sulfoaluminate Cement-Based Materials

Advances in Organic Rheology-Modifiers (Chemical Admixtures) and Their Effects on the Rheological Properties of Cement-Based Materials

Effect of resting time on rheological properties of glass bead suspensions: Depletion and bridging force among particles

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Effect of AH₃-PCE Ultrafine Composites on the Properties of Sulfoaluminate Cement-Based Materials

Effect of AH₃-PCE Ultrafine Composites on the Properties of Sulfoaluminate Cement-Based Materials