Mechanochemically Activated Ternary Modifier Based on Technogenic Mineral Waste for High-Performance Concrete

This article presents the results of a research study on the development and evaluation of a mineral modifying additive for concrete produced from mineral processing tailings, shale waste from shungite production, and silica fume. Compositions of both the modifying additive and concretes based on it were developed. The properties of the mineral modifying additive were studied; mechanochemical activation was applied to increase and modify its activity, and its pozzolanic activity was determined. Depending on the component ratio, CaO absorption ranged from 7.9% to 94%. In the technology of high-strength and functional concretes, high-carbon slag with a fraction of 10-20 mm was used as a partial replacement for natural coarse aggregate. The introduction of 3-15% mineral modifying additive into B40 concrete increased the 28-day compressive strength by 0.19-16%. The greatest increase was observed for concrete containing 8% mineral modifying additive by cement mass. Because compressive strength is not directly correlated with freeze-thaw resistance and water impermeability, capillary suction tests were performed. This non-destructive durability indicator makes it possible to assess concrete permeability, characterize the pore structure, indirectly evaluate freeze-thaw resistance through water-absorption behavior, and estimate the potential resistance of concrete to repeated freezing and thawing. After 24 h, the maximum increase in capillary suction ranged from 4.13% to 5.17%. Direct freeze-thaw testing confirmed a freeze-thaw resistance grade of F400. Three main criteria were used to assign the freeze-thaw resistance grade: average mass loss not exceeding 2%; compliance with the compressive strength ratio XminII >= 0.9 XminI; and the absence of cracks, spalling, and edge-scaling on the specimens.