Effect of polydisperse reinforcement on the fresh and physical-mechanical properties of self-compacting concrete

The development of promising concrete mixtures with improved performance is an important scientific problem of modern building materials science. This article presents the effect of mono and polydisperse reinforcement on the rheological properties of concrete mixtures and the physical and mechanical properties of self-compacting concrete (SCC). A central compositional plan determined the content of polydisperse reinforcement in the composition of the SCC: metal fiber of 0.56% (by volume), polypropylene fiber of 0.35% (by volume). It is shown that the installation of concreted structures with a slope of up to 4% is possible with the following rheological parameters of the concrete mixture: within the spreading grade SF1, the ultimate shear stress is 23-28 Pa, viscosity (spreading test t500 according to EN 12350-8:2019) - 8 - 13 s. At the same time, the lower limit of the identified intervals of rheotechnological parameters is due to the content of metal fiber, with an increase in which from 0.5% to 0.8% (by volume) the workability decreases (from 59 to 60 cm to 54-55 cm) and the ultimate shear stress increases ( by 2.5-3 Pa). The upper limit of the studied parameters is due to the content of polypropylene fiber (0.3-0.4% by volume) and metakaolin (4-5%), with an increase in which the viscosity increases (by 30-35%). Self-compacting concrete has been developed with high values of frost resistance and water resistance, recommended for use in load-bearing building structures, industrial floors, and bending elements.