Development of Ideas About the Rheological Behaviour of Building Mixtures Taking into Account Fractal-Cluster Processes in Their Structure Formation

• Main Authors: Andrey A. Ledenev, Viktor T. Pertsev, Oleg B. Rudakov, Dmitriy E. Ваrabash
• Format: Article
• Language: English
• Published: Voronezh State University 2020-12-01
• Series: Конденсированные среды и межфазные границы
• Subjects: heterogeneous dispersed systems; rheological properties; building mixtures; modelling; fractal-cluster structures
• Online Access: https://journals.vsu.ru/kcmf/article/view/3059

Development of theoretical ideas about the mechanism of the rheological behaviour of building mixtures and the experimental assessment of their rheological properties is a relevant area of physiochemical research of materials. To assess the changes in rheological properties when varying the component composition of building mixtures, it is important to use quantitative indicators characterising the microstructure of the mixtures. Revealing the regularities of the formation of heterogeneous microstructures makes it possible to assess their correlation with the rheological properties of building mixtures at the macro level. The aim of the paper is to discuss the results of the implementation of methodological approaches, theoretical modelling, and experimental assessment of the quantitative indicators of the rheological properties of typical building mixtures. The experimental research methodology is based on the assessment of the rheological properties of heterogeneous dispersed systems (HDS), taking into account fractal-cluster manifestations in their microheterogeneous component. The experiment was carried out using model HDS containing the components of building mixtures. Their rheological properties were determined by rotational viscometry with different compositions of HDS. The fractal dimension D was used for a quantitative assessment of the structural and rheological properties and identification of the patterns of their change depending on the composition of mixtures. The value was determined by mathematical modelling. We analysed model concepts of the rheological behaviour of building mixtures. It was shown that the existing rheological models of an elastic-viscous-plastic medium did not give a complete description of the processes of formation and destruction of the microstructure of concentrated HDS (building mixtures). We carried out an experimental assessment of the effect of the properties of solid phase particles on the change in the structural and rheological characteristics of HDS, taking into account the fractal-cluster principles of their structure formation. We specified the ideas about the mechanism of rheological behaviour of building mixtures. They take into consideration the processes of the formation and destruction of fractal-cluster formations in the microstructure of HDS. It was shown that the fractal dimension D can be one of the quantitative characteristics of the structural and rheological properties. We determined the correlation between the fractal dimension D and other experimental rheological characteristics: the ultimate shear stress and effective viscosity. The obtained results can be used to regulate rheological properties and optimise the technological processes for the manufacture of building materials and products.