USE OF SAND AND LIMESTONE AS FUNCTIONAL FILLERS IN MODIFIED CEMENT BINDERS

Abstract

In the context of increasing the efficiency of modern building materials, there is growing interest in using natural mineral components as functional fillers in cement binder mixtures. The use of sand and limestone, which provides cement economy and significantly affects the microstructure, hydration processes, rheological characteristics and durability of materials, is particularly relevant. At the same time, existing studies mainly consider these components in isolation, which does not allow for a complete assessment of their synergistic effect in the conditions of the local raw material base. The article aims to substantiate the feasibility and effectiveness of the simultaneous use of sand and limestone as functional fillers in modified cement mixtures, taking into account their physicochemical properties, structural role and impact on key performance indicators. To achieve this goal, methods of comparative literature analysis, comparative assessment of physicochemical characteristics and data systematization were used. It was established that sand forms the framework structure of the material and optimizes the water-cement ratio. At the same time, the limestone filler participates in physicochemical reactions, particularly the formation of carboaluminates, and increases the density and crack resistance of the composite. It was found that the combined use of these components in specific proportions (up to 30 % sand and up to 20 % limestone by weight of cement) allows reducing the cement content without significantly reducing the strength. Recommendations are proposed for the rational use of non-standard raw materials (sand waste, limestone dust) and chemical additives to preserve rheological properties. The results obtained have practical value for creating energy-efficient and durable construction composites suitable for use in conditions of limited resources, in particular in regions with a shortage of high-quality raw materials. Prospects for further research are related to an in-depth study of crack resistance and structural changes in composites under long-term loading conditions, as well as the development of multicomponent formulations based on local materials.