Improvement of Polyethylene Glycol in Compatibility with Polycarboxylate Superplasticizer and Poor-Quality Aggregates Containing Montmorillonite

Tan, Hongbo; Gu, Benqing; Jian, Shouwei; Ma, Baoguo; Guo, Yulin; Zhi, Zhenzhen

doi:10.1061/(asce)mt.1943-5533.0001959

Cited by 17 publications

(8 citation statements)

References 21 publications

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“…Other studies [8,9] have reported similar MNT d-spacing expansions by following the same experimental process, as shown in Fig 1 . Nevertheless, other authors [10] reported experiments where the observed d-spacing expansions of MNT clays were not homogeneous and varied depending on the structure of the PCE polymer and the nature of MNT clay. In general, they reported expansions in the range of 4.9-5.5 Å.…”

Section: Introductionsupporting

confidence: 68%

“…Therefore, we infer that the experimental conditions used for the diffraction experiments do not affect the results. where PEG/PEO side-chain is coordinated with two water molecules by hydrogen bonding [9], and arranged in a zig-zag planar disposition [7], the equivalent thickness of one single PEO monolayer can be deduced from the proposed configuration, as presented in 6) with intercalation number deduced from XRD patterns of dried clay pastes (Table 5), it is possible to conclude that the degree of intercalation of PCE side-chains is up to nine times larger and increases with PCE dosage. The error calculated as the difference between theoretical (simplified) calculations and experimental d-spacing are also reported in Table 6.…”

Section: Impact Of Pce Dosage On Na-mnt D-spacing Expansionmentioning

confidence: 99%

“…Fig.1. a) Laboratory XRD patterns for centrifuged-dried MNT samples with different PCE based superplasticisers (adapted from[5]); b) Laboratory XRD patterns for centrifugeddried MNT samples with PCE and PEG based superplasticisers (adapted from[9])…”

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confidence: 99%

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Influence of experimental procedure on d-spacing measurement by XRD of montmorillonite clay pastes containing PCE-based superplasticizer

Borralleras¹,

Segura

Aranda

et al. 2019

Cement and Concrete Research

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This study investigates the influence of the experimental procedure on determining the d-space enlargement of montmorillonite clay (MNT) produced by the absorption of polycarboxylate (PCE) based superplasticizers. d-spacing alterations registered by in situ X-ray Diffraction (XRD) analysis on fresh clay pastes have been compared against the results obtained when clay pastes are previously centrifuged and dried (reference methodology reported in bibliography). Data from experiments show relevant differences between the two methodologies. While MNT clay d-spacing present limited expansion when recorded on samples previously separated and dried, direct XRD for fresh clay pastes shows much larger expansion of inter-laminar space. Clay expansion evolves with the increase of PCE dosage up to 3 times larger than typical data recorded when samples previously dried. The results shown here indicates that information collected following the typical experimental procedure based on sample drying could not be representative of MNT clay interference on dispersion mechanism of PCE superplasticizers.

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Section: Introductionsupporting

confidence: 68%

Section: Impact Of Pce Dosage On Na-mnt D-spacing Expansionmentioning

confidence: 99%

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Influence of experimental procedure on d-spacing measurement by XRD of montmorillonite clay pastes containing PCE-based superplasticizer

Borralleras¹,

Segura

Aranda

et al. 2019

Cement and Concrete Research

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“…Steric hindrance, provided by PEO chain, has been proved as the main force to plasticize the cement particles. In fact, this force mainly depended on amount of S-PCE [62,63]. It was generally believed that a greater amount of S-PCE could provide higher dispersion capacity.…”

Section: Dispersion Modelmentioning

confidence: 99%

Effect of Sodium Hexametaphosphate and Trisodium Phosphate on Dispersion of Polycarboxylate Superplasticizer

Zhang

Liu

et al. 2019

Materials

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Enhancement in dispersion of polycarboxylate superplasticizer (PCE) could be obtained by incorporating retarders in normal concrete. The generally believed reason was that the consumption of free water and polymer at the beginning was reduced by retarding cement hydration. This theory could not convincingly explain why sodium hexametaphosphate (SHMP) was able to promote the dispersion capacity of PCE, while trisodium phosphate (TSP) could not, despite that both TSP and SHMP could obviously retard the cement hydration. The adsorption behavior of PCE and phosphate was investigated and the mechanism was analyzed in order to gain deeper understanding. The results showed that TSP and SHMP delayed the cement hydration, impeded adsorption process of PCE, and increased thickness of adsorption layer. It was interesting that TSP reduced the dispersion, but SHMP enhanced. The reason for this contradiction was due to the difference in composition of adsorption layer. In the PCE-TSP system, this layer was composed of the precipitates (formed by TSP and Ca 2+ ) and the invalided PCE (caused by these precipitates in the immediate vicinity of the cement grains); the invalided PCE was due to the decrease of PCE dispersion. In the PCE-SHMP system, "Inner-phosphate (multi-layers) + Outer-PCE (single layer)" structure was formed to make the PCE work more effective, hence enhancing the dispersion. These results were expected to be useful for the design of highly efficient dispersants. dispersion capacity [26][27][28][29][30]. Based on this, the retarder might hinder the adsorption process of PCE and it was referred to as competitive adsorption [31][32][33][34][35], thereby reducing the dispersion. In addition, the thickness of the adsorption layer should also be accepted as a factor influencing the dispersion of PCE [36,37]. In spite of the decline in adsorption amount of PCE in the presence of retarder, as reported in previous study, the adsorption layer was obviously thickened to enhance the dispersion [37]. On the basis of discussion above, the conclusion could be made that the dispersion capacity of the PCE-retarder system should be associated with the retarding effect of retarder, adsorption behavior of PCE, and the thickness of the adsorption layer.Poly-phosphates, such as sodium tripolyphosphate and sodium hexametaphosphate (SHMP), have been widely used to promote the dispersion ability and dispersion retention ability of the superplasticizer system in real engineering practice. However, mono-phosphates, such as trisodium phosphate (TSP) and sodium hydrogen phosphate, cannot play the same roles as poly-phosphate in commercially available PCE products. If the retardation was the main reason for the enhancement, poly-phosphate and mono-phosphate would both have a similar effect on dispersion of PCE system, because both TPS and SHMP could retard the cement hydration [38]. Therefore, the reason why the poly-phosphate could effectively enhance the dispersion, whilst the mono-phosphate failed cannot be simply explained by the retard...

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“…In the oil industry, the incorporation of inhibitors may significantly impede the swelling of clay minerals (Nehdi, 2014). In addition, polyethylene glycol might be intercalated preferentially into the interlayer to hinder the intercalation of PCE (Tan et al , 2017). Furthermore, the influence of the polymer structure of PCE (Borralleras et al , 2019b), adsorption conformations (Borralleras et al , 2020) and experimental procedures (Borralleras et al , 2019a) on intercalation behaviour in montmorillonite clays has also been investigated systematically.…”

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confidence: 99%

A novel method for solving the impact of clay on concrete workability: dimensional design and mechanism analysis

Liu

et al. 2020

Clay miner.

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Clay often has severe detrimental impacts on cement-based materials. Therefore, it is necessary to investigate the mechanism causing the deterioration to improve the service life of cement-based materials. Based on accurate dimensional analysis, a mechanism that influences clay is proposed: the intercalation of the side chains of superplasticizer molecules in the interlayer space of the clay. To lessen this harmful effect, a new clay-resistant admixture (CRA) possessing cationic groups of small molecular size was synthesized through a novel dimensional design. The length and width of the side chains of this superplasticizer molecule were 9.50–17.50 and 0.25–0.40 nm, respectively, with a radius of ~3.74 nm in solvent, which is larger than the interlayer spacing of montmorillonite (i.e. 1.09–2.14 nm). The longitudinal and latitudinal lengths of the CRA molecule were 0.468 and 9.456 nm, respectively, ensuring intercalation in the interlayer of montmorillonite. The increase in interlayer spacing of the clay was 0.364 nm following addition of polycarboxylate superplasticizer (PCE) plus CRA and 0.632 nm following addition of PCE, which suggests that the CRA plays the role of a ‘sacrificial agent’ that is preferentially intercalated into the interlayer space of clay to further prevent the side chains of the superplasticizer molecules from entering the interlayer. The aim of this study was to propose a suitable means of synthesizing a new CRA to address the impact of clay through dimensional design and mechanism analysis, which contributes to the theoretical study and technological improvement of cement-based materials.

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Improvement of Polyethylene Glycol in Compatibility with Polycarboxylate Superplasticizer and Poor-Quality Aggregates Containing Montmorillonite

Cited by 17 publications

References 21 publications

Influence of experimental procedure on d-spacing measurement by XRD of montmorillonite clay pastes containing PCE-based superplasticizer

Influence of experimental procedure on d-spacing measurement by XRD of montmorillonite clay pastes containing PCE-based superplasticizer

Effect of Sodium Hexametaphosphate and Trisodium Phosphate on Dispersion of Polycarboxylate Superplasticizer

A novel method for solving the impact of clay on concrete workability: dimensional design and mechanism analysis

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