Comprehension of demoulding mechanisms at the formwork/oil/concrete interface

Djelal, Chafika; de, Pascale; Libessart, Laurent; Dubois, Isabelle; Pébère, Nadine

doi:10.1617/s11527-007-9268-3

Cited by 29 publications

(36 citation statements)

References 5 publications

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“…It can be observed that the friction stress decreases in the presence of the oils, and especially of the vegetablebased oil, which confirms the findings in Libessart's dissertation [6]. A new boundary layer comprising water, fines and oil is created.…”

Section: Influence Of the Nature Of Release Agentssupporting

confidence: 84%

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Interactions between Superplasticizer and Release Agents at the Concrete/Formwork Interface

Bouharoun¹,

Vanhove²,

Djelal³

et al. 2012

MSA

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Improving the knowledge of rheological and tribological characteristics of fresh concrete is important to contribute to the progress of construction sites and the final quality of the work. The objective of this study is to identify the effect of a superplasticizer based on polycarboxylic ether on the tribological behavior of fresh concrete at the concrete/formwork and concrete/oil/formwork interfaces. Friction tests on fresh concrete were carried out using a plan/plan tribometer. In order to study the behavior of the superplasticizer close to the formwork, three concretes with 30% of paste and different dosage of superplasticizer were formulated. The results show that the increase of the dosage of superplasticizer reduces the friction stress. The properties of the superplasticizer generate a deflocculating action of concrete grains and lead to a stabilisation of the soap-oil micellae present in the vicinity of the formwork. Thus, the efficiency of superplasticizer depends on the quantity of fines, on the quantity of soap formed and so, on the release agent formulation.

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Section: Influence Of the Nature Of Release Agentssupporting

confidence: 84%

“…In this case, the thickness of the oil film is an important parameter [6,7]. The thicker the film, the less aggregate comes into contact with the plate.…”

Section: Influence Of the Nature Of Release Agentsmentioning

confidence: 99%

Interactions between Superplasticizer and Release Agents at the Concrete/Formwork Interface

Bouharoun¹,

Vanhove²,

Djelal³

et al. 2012

MSA

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“…Although a few muralist precursors raised the question of mortar aesthetic at the beginning of the 20th century [1][2][3][4], it only became a major concern in the last decades [4][5][6][7][8][9][10]. The development of high-performance and self-compacting concretes [11][12][13][14], which show a significant improvement in terms of aesthetics, contributed to develop their use in architecture.…”

Section: Introductionmentioning

confidence: 99%

Characterisation of the variations of tint and the adhesion of pigments onto the surface of mortar

Horgnies¹,

Darque-Ceretti

Gueit

et al. 2015

Construction and Building Materials

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“…These agents reduce adhesion and friction between the concrete and the formwork. As a result, the quality of the product is enhanced and the life of the formwork is extended [11,12]. The most common commercial release agents for concrete are paraffinic and naphthenic derivatives obtained by the distillation of petroleum and frequently improved with chemical additives such as organic acids or modified esters.…”

Section: Introductionmentioning

confidence: 99%

“…The project, ''Substitution of Mineral Oil based concrete mold release agents by non-toxic, readily biodegradable, Vegetable oil based Release Agents'' [33], was undertaken by the European Union, resulting in guidelines on the use of biodegradable release agents as well as tests necessary to evaluate their performance. A substantial amount of research on biodegradable emulsions reported the successful use of rapeseed or soybean oil as a base for the formulations [10][11][12][13][14]17]. However, there is no scientific explanation related to the role of the chemical composition in release agent performance in steel-concrete interfaces.…”

Section: Introductionmentioning

confidence: 99%

Laboratory and field performance of biodegradable release agents for hydraulic concrete

et al. 2015

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Raw vegetable oils and their emulsions have been used as biodegradable release agents for concrete. However, there is no scientific explanation linking the chemical composition to their release performance. The present study was divided into two phases. In the first phase, different vegetable oils with varying degrees of refinement were chemically characterized by middle range Fourier transform infrared spectroscopy (Mid-FTIR), and their viscosities were measured. For comparison purposes, two commercial release agents based on mineral oil were used. In the second phase, emulsions containing bleached soybean oil, water and some emulsifiers were prepared. The performance of the oils and emulsions as demolding agents in steel/concrete interfaces was measured by visual rating, image analysis and bond strength. The results indicate that almost all of the vegetable oils showed better performance than that of the two mineral oil-based agents, which is explained by the higher affinity of glycerol esters for metal surfaces and higher intermolecular interactions. The Mid-FTIR espectrum analysis indicates that oils having larger absorption areas under the curve at the methylene group exhibit better performance as release agents. In addition, the Mid-FTIR analysis allowed identification of the main molecular groups and differentiation between oil samples. In the second phase, the water/oil emulsion stabilized with organophilic clay performed the best. In addition to the lubricating effect of the emulsion, the better performance was also due to the saponification reaction between the acylglycerides and the Ca(OH) 2 . The tangential adhesion was reduced to approximately 64 % compared to that of a mold without a release agent.

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Comprehension of demoulding mechanisms at the formwork/oil/concrete interface

Abstract: OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible.

Cited by 29 publications

References 5 publications

Interactions between Superplasticizer and Release Agents at the Concrete/Formwork Interface

Interactions between Superplasticizer and Release Agents at the Concrete/Formwork Interface

Characterisation of the variations of tint and the adhesion of pigments onto the surface of mortar

Laboratory and field performance of biodegradable release agents for hydraulic concrete

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