Rheological Properties of the System «Composite Gypsum Binder — Superplasticizer — Water»

Results of the study of rheological characteristics of mixes on the basis of the composite gypsum binder (CGB), which includes gypsum binders of α-modification G-5BP (G-5) and β-modification GVVS-16 (G-16); Portland cement TSEM 1 42.5N, multi-component fine-dispersed mineral additives and a surface-active additive on the base of lingo-sulfates and modified polycarboxylates SikaPlast 2135, are presented. The improvement in viscoplastic properties is observed at the SP dosage of 0.3–0.5%, this makes it possible to reduce the point of fluidity almost to zero and reduce the effective viscosity by several times. Dosages of SP over the optimum level determine the influence on the strength of gypsum-cement stone accompanied by reduction in water demand of CGB and the average size of pores of the gypsum cement stone. At dosages of SP which are not over the optimal, a decisive influence on the strength of gypsum cement stone has its deflocculating action which is accompanied by the reduction in water demand of CGB and the average size of pores of gypsum cement stone. When increasing the dosage over the amount that causes the complete destruction of floccules of the initial suspension, the strength of gypsum cement stone is reduced due to blocking SP crystallization ties. The total effect depends on which of these factors prevails when introducing it.

M.Yu. DREBEZGOVA, Engineer Belgorod State Technological University named after V.G. Shukhov (46, Kostyukov Street, 308012, Belgorod, Russian Federation)

1. Drebezgova M.Yu. Features of hydration composition plaster knitting in the presence of superplasticizer Sika Plast 2135. Vestnik BGTU im. V.G. Shukhova. 2017. No. 5, pp. 20–23. (In Russian). 
2. Chernysheva N.V. The Use of Anthropogenic Raw Materials for Increase of Water Resistance of a Composite Gypsum Binder. Stroitel’nye Materialy [Construction Materials]. 2014. No. 7, pp. 53–56. (In Russian). 
3. Belov V.V., Burianov A.F., Yakovlev G.I., Petropavlovskaya V.B., Fisher H.-B., Maeva I.S., Novichenkova T.B. Modifikatsiya struktury i svoistv stroitel’nykh kompozitov na osnove sul’fata kal’tsiya [Modification of structure and properties of structural composites on the basis of calcium sulfate]. Moscow: De Nova. 2012. 196 p. 
4. Gordina A.F., Yakovlev G.I., Polyanskikh I.S., Kerene J., Fisher H.-B., Rakhimova N.R., Bur’yanov A.F. Gypsum Compositions with Complex Modifiers of Structure. Stroitel’nye Materialy [Construction Materials]. 2016. No. 1–2, pp. 90–95. (In Russian). 
5. Skuyans, Yu.R., Chuguev A, S., Horometskiy V.G. Investigation of the rheological properties of gypsum mixtures with additives of surfactants. Proceedings of the Latvian Academy of Agricultural Sciences. Building materials and structures for rural construction. 1984. Issue 209, pp. 19–23. (In Russian). 
6. Uryev N.B. Fiziko-khimicheskie osnovy tekhnologii dispersnykh sistem i materialov [Physicochemical foundations of dispersed systems and materials technology]. Moscow: Khimiya. 1988. 256 p. 
7. Uryev N.B. Dynamics of structured disperse systems. Kolloidnyi zhurnal. 1998. Vol. No. 5, pp. 662–683. (In Russian).