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The knowledge of the rheological properties of polymers makes their use interesting in various fields of applications, such as food industry, cosmetics, enhanced oil recovery or construction materials. Whatever the application, the effect of temperature and concentration on these properties is of great importance. This study covered a wide range of concentrations from 0.2 w/% to 1 w/%, and temperatures from 10 °C to 80 °C. The results obtained provide interesting information regarding the effects of the temperature and concentration of the aqueous solutions of the polymer since they reveal that the rheological properties remained practically unchanged in the temperature range considered. The impacts of shear rate, temperature and concentration on the flow behavior were analyzed. Small-amplitude oscillatory shear measurements were performed, and the results obtained show that the apparent viscosity is strongly influenced by the concentration of the aqueous solution of HEC, exhibiting a marked non-Newtonian shear-thinning behavior at different temperatures. The flow behavior is well described by several rheological models. The effect of temperature on the kinematic viscosity was fitted with the Arrhenius model; the behavior of this model in relation to experimental viscosity values was suitable and the linear fit showed good regression coefficients. The dynamic state was well described with the generalized Maxwell model.

The composite materials present weakness to shocks and impact, studies are carried out in order to minimize the consequences of these defects, solutions are adopted for temporary or permanent. solutions are adopted for temporary or permanent repairs. These repairs are applied to the defects present on the composite materials of the "Low Energy Impact" type aircraft structure using the Epoxy matrix composite patch method: EPOCASTA50-1, a non-diluted resin reinforced with glass of the same type as that of the aircraft fuselage. The effectiveness of these repairs is verified using the study of conventional tensile behavior. For the characterization of the damaged state and validation of the results, non-destructive NDT control is carried out on specimens developed under the same conditions as repair plates attached to the fuselage plane.

Colloque avec actes et comité de lecture. Internationale.; International audience; This article examines the effect of the concentration of a surfactant on the rheological properties of Algerian crude oil, when the yield stress, the apparent viscosity, the pressure drop and flow rate are evaluated. The surfactant choice is Toluene; different concentrations (2%, 3% and 6%) are tested to improve the transportation capacity of Algerian crude oil. The rheological tests are carried out using the rheometer AR2000 from TA Instruments with a coaxial cylindrical geometry type Couette. Because of large contact surface of the cylinder, one can obtain a good accuracy of the measurements at low viscosity values. Different temperatures were tested. The experimental results show that the rheological behavior of system (crude oil / Toluene) exhibits a non-Newtonian behavior at a low shear rate It was also noted that the increase in the surfactant concentration has an effect on the rheological parameters, the apparent viscosity, yield stress significantly decreased with the addition of toluene. The results obtained also show that the increase in the concentration of the additive also has an effect on the transport capacity of the crude oil, the addition of 6% of toluene has increased the flow rate of the crude oil by 44%.

Colloque avec actes et comité de lecture. Internationale.; International audience; The use of anionic polyelectrolytes is great technological importance to control the stability and flocculation behavior of colloidal suspensions. They are widely used in various industrial products, such as paints, coatings, ceramics, pesticides, pharmaceuticals, cosmetics, and drilling fluids, to modify the rheology and control the stability of the systems.In this investigate, rheological measurements obtained by a coaxial cylinder viscometer (shear rate from 0 to 700 s-1), were carried to highlight the effect of two anionic polyelectrolytes such as, xanthan gum and sodium carboxymethylcellulose (Na-CMC) on the rheological properties of the bentonite suspension. Firstly, Herschel-Bulkley model was used for the flow curves of studied bentonite suspension whose the concentration in solid varies between 3-6%, the regression coefficient > 0.997 for all studied system. Secondly, electrokinetic measurements on all studied suspensions were also carried. Finaly, to asses the influence of polyelectrolytes on bentonite suspension, the rheological tests have been carried out on the polyelectrolytes solutions in absence of bentonite. The rheological behavior of xanthan solutions is shear-thinning non-Newtonian viscosity with yield stress. The obtained results showed that the yield stress and the consistency index increase with increasing bentonite concentration, on the other hand the flow index values decrease. It can be explained that the bentonite has a microscopic structure in platelets. It was noted also, the yield stress observed on rheograms is due to the internal fluid structure that forms at rest between the platelets. In the absence of flow, the platelets form rigid aggregates that are resistant to a certain value. from this yield , the structure is destroyed and the wafers are aligned with the flow. Also, the obtained results of the electrokinetic study, have showed an increase of the zeta potential of CMC and xanthan dispersions when the concentration of polymer in solution increases

Self-compacting sand concrete (SCSC) can be regarded as a flowing sand concrete, containing as principal ag- gregate natural sand, which can be cast without compaction or vibration. Due to the finesses of aggregates in SCSC, it re- quires a high amount of fine materials than other types of concretes. This paper studies the effect of marble powder con- tent (MP) on the properties of the sand concrete (SCSC) at fresh and hardened states. The properties of the fresh prepared mixes tested are the mini-slump flow, the V-funnel flow time and viscosity. At the hardened state, the parameter which has been determined is the 28-day compressive strength. The obtained test results show that the increase of MP content in SCSC, from 150 kg/m 3 to 350 kg/m 3 , improves the properties at fresh state by decreasing v-funnel flow time (from 5s to 1.5s) and increasing the mini-cone slump (from 28cm to 34cm). With the use of 250 kg/m 3 of MP we can reach the high- est initial viscosity while retaining good fluidity at high rotational speeds, compared to the MP contents of 150 kg/m 3 and 350 kg/m 3 . In other hand, the 28-days compressive strength decreases with an increase of MP content.

Colloque avec actes et comité de lecture. Internationale.; International audience; Différentes méthodes expérimentales de réduction de la viscosité du pétrole brut ont été étudiées pour améliorer les propriétés d'écoulement. Dans cette étude, nous avons utilisé du Toluène pour réduire la viscosité. Les essais rhéologiques ont été réalisés en utilisant le rhéomètre AR2 ; de TA-Instruments à différentes températures 10°C, 15 °C et 20°C. Plusieurs concentrations de l'additif ont été testées, 2%, 3% et 5%. Les points expérimentaux des courbes d'écoulement du pétrole brut montrent un comportement non-newtonien qui peut être décrit par la loi Herschel-Bulkley. Les résultats expérimentaux montrent que la température influe considérablement sur l'évolution des courbes d'écoulement et provoque une diminution de la viscosité apparente du pétrole brut. Cette étude montre que le Toluène utilisé a un effet significatif sur la réduction de la viscosité apparente de pétrole brut algérien. Les résultats sont présentés et discutés.

De nos jours, le béton incorpore dans sa matrice non seulement des ajouts cimentaires mais aussi des adjuvants chimiques qui améliorent ses propriétés rhéologiques et physico-mécaniques à l'état frais et durcis. Dans le but de résoudre le problème du déficit de production de ciment afin de réduire l'émission des gaz à effet de serre, on utilise des ajouts minéraux actifs tels que la pouzzolane naturelle et la fumée de silice pour substituer partiellement le ciment. L'objectif de cette étude est de mettre en évidence l'influence de l'ajout de pouzzolane naturelle et de la fumée de silice sur le comportement rhéologique et les propriétés physico-mécaniques des coulis de ciment en présence d'un superplastifiant de type copolymère acrylique (SP). Pour cela, nous avons effectué des essais rhéologiques à l'aide du rhéomètre AR2000 qui donne les courbes d'écoulement des systèmes eau-ciment-SP, eau- ciment-pouzzolane-SP et eau-ciment-fumée de silice-SP à différents dosages de SP. Ces dernières ont été modélisées selon le modèle rhéologique Hershel-Bulckley. Les mélanges étudiés présentent un comportement newtonien à des vitesses de cisaillement élevées. Ces essais nous ont permis de déterminer le point de saturation en SP qui est de 1,5%. Les paramètres rhéologiques montrent que les coulis de ciment avec ajout de la pouzzolane diminuent la consistance en fonction de l'augmentation du SP, par contre, les pâtes cimentaires contenant la fumée de silice présentent une forte consistance. En ce qui concerne les essais mécaniques, il est observé une nette amélioration des résistances mécaniques en compression avec 10% d'ajouts de la pouzzolane.

The purpose of this work is to investigate the effect of the addition of salts in the form of calcium chloride, sodium chloride and potassium chloride on the rheological and electrokinetic properties of diluted sodium carboxymethylcellulose (Na-CMC) dispersions (0.50%). The rheological data of a water-CMC-salt system were obtained using coaxial cylinder viscometer covering a wide range of shear rate (0 to 600 s-1). Ostwald–de Waelepower law was used for fitting flow curves of various samples. The presence of salts in CMC aqueous solutions leads to the reduction of the consistency index and the increase of flow index as salinity increases. When the concentration of salts is greater than 3%, the rheological parameters of CMC solutions in saline medium are quasi stable. The electrokinetic measurements show an increase of the zeta potential of CMC dispersions when the concentration of salts in solution increases. Calcium chloride caused the greatest increase in zeta potential. Excluding the monovalent cations, the divalent cation is able to reverse the sign of the zeta potential from negative to positive. Key words: Rheology, zeta potential, salt, carboxymethylcellulose sodium (CMC).