Heavy concrete is widely used as the main structural material in irrigation and drainage construction, ensuring high reliability and safety of the complexes during operation. The main quality criteria for heavy concrete are their operational characteristics. The binder was Portland cement of class CEM I 42.5N. The dispersed composition, technological and strength characteristics of cement and cement stone obtained from it were determined using sieve analysis, pycnometric method, determination of bending and compressive strength in accordance with standard methods. Natural sand was used as a fine aggregate. Granite crushed stone was used as a coarse aggregate. Water was used to mix the concrete mixture. Melflux 5581 F superplasticizer was used as a plasticizing additive. Microsilica was used as an active mineral additive. Chopped basalt fiber was chosen for dispersed reinforcement of concrete stone. To determine the efficiency of water interaction with the matrix of the developed concrete and, as a consequence, the efficiency of diffusion processes inside the matrix, affecting the destruction of the concrete stone structure and possible moisture loss during irrigation, the porosity of concrete, its water absorption and water resistance were determined. Analysis of the obtained data shows that the introduction of a complex modifier together with basalt fiber reduced the water absorption index by 57.8% compared to the control. The water resistance of the modified concrete in composition 5 increased by 4 loading stages compared to control composition 1. Improvement of hydrophysical properties of modified concrete was established: water absorption decreased by 57.8%; water resistance grade increased by 4 loading stages in comparison with the control composition. After 600 cycles of frost resistance testing, the mass loss was 1.5-1.8%, the strength decrease was 9.1%-10.2%. The proposed modification with a complex additive together with basalt fiber allows obtaining high-quality heavy concrete with improved hydrophysical properties.
