1,721,075 research outputs found
RHEOLOGICAL MODELS FOR CALCIUM CARBONATE/KAOLIN SUSPENSIONS FOR PAPERCOATING APPLICATIONS
No full textRHEOLOGICAL PROPERTIES OF CALCIUM CARBONATE CONCENTRATED SUSPENSIONS: EFFECTS OF SOLID CONTENT AND DISPERSANT CONCENTRATION
No full textFLOW BEHAVIOR OF FRESH PORTLAND CEMENT PASTES
No full textPortland cement pastes prepared at various water/cement ratios were studied using the rate-controlled coaxial cylinder viscometer Rotovisko-Haake 20, system M5-oscillatory measuring device MV2P with serrated surfaces. The tests were performed under both continuous and oscillatory flow conditions. In this article, experimental shear stress and shear rate data were fitted very satisfactorily with a model proposed by the authors. Excellent results were achieved also by applying the Quemada equation. Oscillatory flow data gave further information on the workability of the pastes investigated. In addition, the influence of two different commercial superplasticizing agents (Concretan RX and Ergomix 1000, the first based on polycyclic copolymers with modified structures carrying hydroxylated side chains, the second on a modified polyacrylic resin) was studied with the aim of determining their optimum dosage. In the case of Ergomix 1000, agreement between the optimum dosage determined rheologically and that recommended by the producer was obtained
RHEOLOGICAL BEHAVIOR OF CALCITE SLURRIES. EFFECT OF DEFLOCCULANTS ADDITION
No full textIn the present work, the influence of the addition of some dispersing agents employed for maximizing the solid loading of calcium carbonate concentrated suspensions was investigated. Three commercial deflocculants were used:a sodium salt of a benzenedisulfonic acid (Tiron), a sodium polyphosphate, and an aurintricarboxylic acid, triammonium salt (Aluminon). Calcium carbonate aqueous suspensions were prepared at various solid volume fractions (0.270 to 0.382). Rheological tests were carried out at 25°C by using the rate-controlled coaxial cylinder viscometer Rotovisko-Haake 20, system M5-oscillatory, measuring device SV2P with serrated surfaces. The tests were performed under both continuous and oscillatory flow conditions. The application of rheological techniques permitted highly accurate evaluation of the optimum dosage of the deflocculants, i.e., the critical concentration at which the maximum reduction in viscosity is detected. Generally, Aluminon and sodium polyphosphate behaved as the best dispersing agents for the calcite suspensions studied, i.e., they showed their optimum dosage at a concentration lower than that of Tiron and provided low viscosity values for the entire concentration range explored
INFLUENCE OF DISPERSANT NATURE AND CONCENTRATION ON THE RHEOLOGICAL PROPERTIES OF KAOLIN SUSPENSIONS
No full textRHEOLOGICAL PROPERTIES OF ALUMINIA SLURRIES: EFFECT OF DEFLOCCULANT ADDITION
No full textIn the present work the influence of the addition of some dispersing agents employed for maximizing the solid loading of alumina concentrated suspensions has been investigated. Three commercial deflocculants were used: a sodium salt of a benzenedisulfonic acid (Tiron), a sodium polyphosphate, and an aurintricarboxylic acid, triammonium salt (Aluminon). Rheological tests were carried out at 25°C under continuous flow conditions by using the rate-controlled coaxial cylinder viscometer Rotovisko-Haake 20, system M5-osc., measuring device SV2P with serrated surfaces. The application of rheological techniques permitted evaluating the efficiency and optimum dosage of the dispersing agents employed on the alumina slips examined, i.e., the critical concentration at which the maximum reduction in viscosity is detected
EFFECT OF VARIOUS SUPERPLASTICIZERS ON THE RHEOLOGICAL PROPERTIES OF PORTLAND CEMENT PASTES
No full textIn the present work, the influence of the addition of some superplasticizers employed for maximising the solid loading of Portland cement pastes has been investigated. Cement pastes were prepared from deionized water and a commercial manufactured ordinary Portland cement 32.5 R (produced by Buzzi Unicem). Cement and water were mixed with a vane stirrer according to ASTM Standard C305. The water/cement ratio was kept fixed at 0.32. Three commercial superplasticizing agents produced by Ruredil were used: they are based on a melamine resin (Fluiment 33 M), on a modified lignosulphonate (Concretan 200 L), and on a modified polyacrylate (Ergomix 1000). Rheological tests were carried out at 25 °C by using the rate controlled coaxial cylinder viscometer Rotovisko–Haake 20, system M5-Osc., measuring device MV2P with serrated surfaces. The tests were performed under both continuous and oscillatory flow conditions. Ergomix 1000 presents a different behaviour as that of the other two superplasticizers studied, because it shows a marked shear-thickening behaviour above a critical deflocculant concentration and slight elastic effects particularly at high dosages as well
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