Carbon-containing modifier for fluoranhydrite binder

Introduction. In order to widen the functionality of construction and building materials and widespread electrically conductive building constructions, it is highly recommended to reduce cost of the solutions. This can be achieved by replacing binders with the industrial by-products. At the same time, there are a few articles about adjustment of electrically conductive properties of materials based on by-product binders and this field is of a great importance. Also, highly dispersed particles in modifiers and their role might be considered as important to find out, especially when such additives are used to improve structure and properties of composites. Methods and materials. To study the possibility of controlling the electrical properties of the matrix, compositions based on fluoroanhydrite, sodium sulfate as a hardening activator, and UPC-MIX-1 suspension as an electrically conductive additive, were made. The effect of UPC-MIX-1 suspension on the electrical performance and structure formation of a mineral matrix containing dispersed carbon black particles was studied. The polydisperse nature of the modifying additive and the ratio of the nanodispersed and microdispersed parts of the solid phase were determined. Indicators for calculating the specific volumetric electrical resistance were determined by the probe method. The influence of the dispersed additive on the characteristics of the fluoroanhydrite composite was evaluated by standard laboratory methods. Features of structure formation were evaluated using the methods of physicochemical analysis. Results and discussion. It was confirmed that a fluoranhydrite-based mineral binder with sodium sulfate has moderate physical mechanical properties and might be used as a substitute for gypsum binder. The usage of an electrically conductive additive as a modifier enhances such mechanical properties as flexural compressive strength and compressive strength which increase by 51% and 65% correspondingly. Also, hydro physical properties have been improved, for instance the coefficient of softening for the FD-4 sample has increased by 39%, and the water absorption by mass for the same sample has decreased by 36%. Specific volume electrical resistance has decreased by 49–52% and equals13,6 kOm • cm, 8% of electrically conductive additive being added. The physical and technical properties of the presented composite are due to significant changes of the physical and chemical properties including the features of structure formation. Conclusions. The obtained compositions require extra optimization in order to be used as a heating component. At the same time, the achieved electrical conductivity is sufficient to level the electrostatic effect of self-leveling floors. Regularities in the formation of the structure of the fluoroanhydrite composite have been established, which manifest themselves in the formation of a larger number of contacts for the intergrowth of crystalline hydrate new formations ensured by the presence of a nanodispersed part in the modifying additive.