Interactions between fluoride ions and cement paste containing superplasticizer

Matsuzawa, Kazuki; Atarashi, Daiki; Miyauchi, Mutsumi; Sakai, Etsuo

doi:10.1016/j.cemconres.2016.10.006

Cited by 16 publications

(4 citation statements)

References 20 publications

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“…Another approach by Lange et al established a correlation between the so-called HLB-value (hydrophilic-lipophilic balance) and the effects of PCEs to the rheological properties of cement and concrete pastes [16,17]. Beside these examples, a lot of research is in progress to optimize superplasticizers for various applications and (blended) cements, for example in terms of robustness and effectiveness [18][19][20][21][22][23]. Because of the high diversity of cementitious systems and potential structures of superplasticizers, general simulating approaches are not established yet and will probably be limited in the future as well.…”

Section: Introductionmentioning

confidence: 99%

Fluorescence Microscopic Investigations of the Retarding Effect of Superplasticizers in Cementitious Systems of UHPC

Wetzel

Middendorf

2020

Materials

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The adsorption of superplasticizer molecules to particle surfaces in cementitious systems is a very important aspect for the desired liquefaction of pastes and concretes. This way, the comb shaped polymers shield attractive forces between the particles and induce a well-dispersed, homogeneous suspension. These admixtures allow the usage of fine fillers even in combination with low amounts of mixing water, and thus, are the basis for modern high performance concretes. However, the adsorption does not cause beneficial effects only: The polymer covered particle surfaces, especially clinker, are hindered to interact with water, thus hydration is retarded. This is the reason for lower early strength and is very disadvantageous for certain applications. Today it is known that the molecular structure of the polymers, for instance the chain length and charge density, affects the retardation strongly. The complexity and diversity of cementitious systems is the main reason why research in this field is quite empiric and time as well as cost intensive. To investigate the adsorption of superplasticizers in various systems in-situ, a fluorescence microscopic approach was applied: By staining the polymers with fluorescent dye they become localizable and the adsorption quantifiable. This work shows the influence of molecular structure to adsorption characteristic of different polymers and the correlation to the retarding effect of superplasticizers, especially concerning the presence of silica fume, which is indispensable for ultra-high performance concrete (UHPC).

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Section: Introductionmentioning

confidence: 99%

Fluorescence Microscopic Investigations of the Retarding Effect of Superplasticizers in Cementitious Systems of UHPC

Wetzel

Middendorf

2020

Materials

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“…In the experimental range (Figure 1d), the water reducer increased the fluidity well, without drastically weakening both setting times and compressive strength. This is due to the effect of naphthalenesulfonate on the dispersion and surface lubrication of binder particles [43,44].…”

Section: Factors Affecting the Solidification Performancementioning

confidence: 99%

Metakaolin-Reinforced Sulfoaluminate-Cement-Solidified Wasteforms of Spent Radioactive Resins—Optimization by a Mixture Design

Wang

Liu

et al. 2022

Coatings

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Cement solidification is a main technique for radioactive waste treatment to reduce its risk to the environment and human health. However, this method underperforms when dealing with spent radioactive ion-exchange resin, taking much space, and costing much money for final disposal. In this work, simulated spent radioactive resin was solidified using a metakaolin-reinforced sulfoaluminate cement system, which was optimized by a mixture design based on the effects of components and parameters, and the durability of solidified wasteforms was assessed in terms of strength and Cs(I) leaching. Solidified by an optimized formula of 40 wt.% spent resin, 55.8 wt.% sulfoaluminate cement, 2.2 wt.% metakaolin, and 2 wt.% water reducer, the resin loading in wasteforms reached 64% and the compressive strength 13.7 MPa. The dominant mineral phases of hydration products were ettringite crystalline of acicular and columnar morphology, with small amounts of scattered amorphous clusters of aluminum gels and C–S–H gels. Metakaolin, a source of aluminum, promoted the growth of ettringite, which facilitated (1) the encapsulation of resin beads with high strengths, even in acidic environments or during frequent freezing-thawing, and (2) the retention of Cs(I), with a 42 day leaching rate of 2.3 × 10−4 cm/day. This work offers a technical justification for spent resin solidification in the metakaolin-reinforced sulfoaluminate cement system, which is an applicational solution for the efficient treatment of radioactive waste.

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“…Fluorine compounds can also enter the environment through anthropogenic activity which is associated with urbanisation and industrial development. The main sources of fluorine in surface water are fertilizer and pesticide industry, as well as brick and cement factories [1,2]. _________________________ 1 Wrocław University of Science and Technology, Faculty of Environmental Engineering, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland, corresponding author A. Klimonda, e-mail address: aleksandra.klimonda@pwr.edu.pl Fluorine is a chemical element of atomic number 9 of the halogen group, a poisonous yellow irritating gas with a strong odour.…”

Section: Introductionmentioning

confidence: 99%

Removal of fluoride ions by ultrafiltration in the presence of cationic surfactants

Klimonda

Grzegorzek

Majewska-Nowak

2017

Environ. Protect. Eng.

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The usability of surfactant-aided ultrafiltration for removal of fluoride ions from aqueous solutions has been investigated. The experiments were conducted with the use of cellulose and polyethersulfone membranes. Fluoride solutions containing 10 and 100 mg F-/dm 3 and cationic surfactants: octadecylamine acetate (ODA) and hexadecylpyridium chloride (CPC) were used in the experiments. The concentration of surfactants amounted to 320-960 mg/dm 3. Ultrafiltration process was run under a transmembrane pressure of 0.2 MPa. In the course of experiments, the effects of initial fluoride concentration, surfactant concentration and membrane type on the fluoride retention coefficient as well as the permeate flux were studied. It was found that the increase of the surfactant concentration effected in improvement of the separation efficiency. On contrary, the permeate flux decreased upon increase of the surfactant concentration. The process efficiency was also strongly influenced by the membrane and surfactant type. The permissible concentration of fluoride in the final product (below 1.5 mg F-/dm 3) was obtained for the test with initial solutions containing 10 mg F-/dm 3 , polyethersulfone membrane and CPC concentration equal to 644 and 966 mg/dm 3 .

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Interactions between fluoride ions and cement paste containing superplasticizer

Cited by 16 publications

References 20 publications

Fluorescence Microscopic Investigations of the Retarding Effect of Superplasticizers in Cementitious Systems of UHPC

Fluorescence Microscopic Investigations of the Retarding Effect of Superplasticizers in Cementitious Systems of UHPC

Metakaolin-Reinforced Sulfoaluminate-Cement-Solidified Wasteforms of Spent Radioactive Resins—Optimization by a Mixture Design

Removal of fluoride ions by ultrafiltration in the presence of cationic surfactants

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