Normalization оf Fine Aggregate Granulometry fоr Struсturаl Соnсrete

It must be noted that the construction industry of the Republic of Belarus is forced to use fine aggregate for low-quality concrete due to the lack of high-quality natural sand in many regions of the country. When using this aggregate in the preparation of concrete mixtures and mortars, an increase in cement consumption is required to confirm the quality of the concrete. The research results of this work can be used to improve the quality of fine aggregate when used in concrete. The technology for producing normalized (enriched) sand of the required granulometry has theoretically and experimentally proven itself positively due to the introduction into natural (fine, medium) sand of fractions of granite screenings ≥(0.5–0.6) mm in size, formed at the RUPP “Granit” of the Brest region Belarus in the production of coarse aggregate for concrete. A computer program “Normalization” (registration number 022 dated 03/07/2024) has been developed to calculate the required ratio of the starting material – natural sand (characterized by a fineness modulus: 0.9 < Mk < 2.5) and processed (prepared) granite screenings of size ≥(0.5–0.6) mm to ensure the required granulometry of enriched sand with Mk = 3.25–3.50. All conditions have been identified for obtaining a material of any granulometric composition, characterized (if there is such a need) by a particle size modulus within the limits recommended by the current technical regulatory legal acts (TNPA): 2.0 < Mk < 3.5. The effectiveness of the technology for normalizing the granulometry of fine-grained natural sands has been experimentally confirmed and is determined by an increase in concrete compressive strength up to 25–40 %, axial tensile and shear strength up to 35–45 %, a decrease in the delamination rate (solution separation and water separation) by 30–47 %, as well as increasing the elastic-deformation characteristics and operational properties (waterproofing, water, salt and frost resistance) and the protective ability of concrete in relation to steel reinforcement, with an assessment of the degree of its corrosion damage. Industrial testing has confirmed the possibility of reducing the cement content in concrete by 10–20 % without deteriorating its physical and mechanical properties. Based on the totality of research results, it was determined that the method of enriching natural sand with large fractions of granite screenings can be used for concrete for various purposes without restrictions.