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Communication Dans Un Congrès Année : 2013

Bubbles stability in a yield stress fluid

Résumé

Non-bearing materials currently used in building applications (walls or bulkheads) are generally formed by panels or blocks. Such materials require good thermal performances and minimal mechanical strength. Mineral foams are relevant solutions. We focus on calcium sulfate foams containing a large amount of air trapped in bubbles. The foam production starts with fluid suspension obtained by quick mixing of water, mineral binder and surfactants. Foaming is applied before the quick setting of the mineral matrix. To study the interaction between foaming and rheological properties evolution, we use a transparent fluid model (dispersion of carbopol 676 in water). The air bubbles stability in yield stress polymer gel is analyzed by picture processing. carbopol gel is placed in plexiglas container. Bubbles are inserted with a variable volume using a syringe for injection controlling gas pressure. We start with the study of single bubble in different carbopols gels to model the change effect of rheological properties (setting effect). Bubbles sizes and internal pressure evolve according to thermodynamical laws. The foam stability is mostly conditioned by coalescence phenomena. It consists on the two bubbles fusion in contact by the membrane destruction which separated them. Experiments reveal that a small amount of surfactants is compulsory to preserve foam structure. Coalescence phenomenon is studied on our model yield stress fluid following the meet condition of two injected bubbles. The type and the surfactants dosage generate a wide range of configuration. Results enable us to understand better the foams behavior at fresh state. It gives us tools to optimize the formulation regarding mechanical and thermal properties targets.

Domaines

Génie civil
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Dates et versions

hal-00995127 , version 1 (22-05-2014)

Identifiants

  • HAL Id : hal-00995127 , version 1

Citer

Gabriel Samson, Annabelle Phelipot-Mardelé, Christophe Lanos. Bubbles stability in a yield stress fluid. 8th Annual European Rheology Conference, Apr 2013, Leuven, Belgium. ⟨hal-00995127⟩
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