THE USE OF COMPOSITE BINDERS AND NANOMODIFIERS FOR FIBER-REINFORCED CONCRETE

The article presents the results of studies on the production of fiber-reinforced concrete with mineral fibers produced in a plasma reactor, composite binders and nanomodifying additives. For dispersed reinforcement of concrete, basalt mineral fibers obtained by the electrothermal method in a plasma-arc reactor were used. To reduce the negative impact of Portland cement, composite binders based on Portland cement and fly ash were used. Fly ash meets the requirements of standards and is suitable for using it as a part of building materials. The nanosilica produced at an electron accelerator was used for comparison. The introduction of nanosilica improves the mechanical properties of cement by accelerating the hydration processes of Portland cement, improving the microstructure and changing the phase composition of the cement stone. The optimal content of fly ash in the composite binder, which allows obtaining high mechanical properties, has been determined. To reduce water content in the binder super plasticizer polycarboxylate type was used. The mechanical properties of fiber-reinforced concrete with ordinary Portland cement, composite binder with fly ash and Portland cement modified with nanosilica were studied. The use of composite binder and the introduction of nanosilica lead to an increase in compressive and flexural strength of fiber-reinforced concrete. The analysis of the microstructure of cement stone by scanning electron microscopy was carried out. The change in the structure of cement stone with the introduction of fly ash and nanosilica and their influence on the surface of mineral basalt fiber is shown. Differential thermal analysis of cement systems showed a change in the phase composition and basicity of the formed calcium hydrosilicates when fly ash and nanosilica are introduced into the binder.