DEVELOPMENT OF CONCRETE MIXTURES BASED ON AGGREGATES FROM DIFFERENT REGIONS OF UKRAINE TO PRODUCE HARDENED CONCRETE OF THE SAME STRENGTH CLASS

Abstract

The use of regional aggregates reduces logistics costs and increases the profitability of construction work, but requires an individual approach to the design of concrete mixtures. The article presents the results of designing the composition of concrete mixtures using aggregates from four different regions of Ukraine using carboxyl-containing polymers as modifiers. The main purpose of the study was to ensure the same mobility of mixtures and strength class of hardened concrete stone, taking into account the characteristics of regional ingredients, namely local fine aggregate. The coarse aggregate chosen as a constant was crushed stone from igneous and sedimentary rocks, fraction 5-20, and binder (Portland cement) CEM II/A-LL 42.5 R. The experimental part involved the selection of the recipe, in particular the optimal dose of the modifying additive for each composition of the concrete mix. In general, the composition of concrete mixtures was determined by the calculation and experimental method with the preliminary application of the absolute volume method and further refinement of the recipe based on trial batches, which made it possible to optimize the content of components taking into account the actual properties of materials and ensure compliance with design requirements. The main physical and mechanical characteristics of concrete mixtures were determined, including fresh mobility and hardened concrete strength. Tests have shown that all developed concrete mixtures compositions correspond to mobility class S4, and hardened concrete corresponds to strength class C32/40 with a certain margin, which confirms the effectiveness of the proposed design approach. It was found that the optimal dosage of the carboxyl-containing modifier required to achieve this goal significantly depends on the properties of the regional components of the mixture. The results confirm the need for an individual approach to designing the composition of concrete mixtures, even with the same requirements for their performance.