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 effect of different composition sols on change of structure and properties of cement stone

One of the most rapidly developing directions in science of structural materials is the application of nanotechnology for development of new generation concrete. To date, nanodispersed additives were widely used in technology of concrete, because they allow increasing its main physicalmechanical properties. The use of effective additives contained nanoparticles in its composition allows to optimize structure of concrete, and also to reduce a consumption of the most expensive component – cement. The need to make new available and rather inexpensive modifiers of cement and concrete products is due to the resource intensive, difficulty of its receiving, therefore, high cost and, respectively, a market price. The article discusses the production of additives in the form of sols on the basis of the chemical elements of VI group of the periodic system of D.I. Mendeleev, in particular of sulfur and chromium, and its use for modification of cement stone. The main characteristics of aqueous solutions of sols were defined by physical and chemical methods of researches and calculation. The content of the colloid additives in cement stone was optimized as a result of the conducted experimental studies, it was determined that the kinetics of cement strength setting depends on the type and amount of sols. The content of sols in cement stone is about thousand fractions of binder mass, i.e. its strength increases at the microlevel. That gives significant saving of the presented additives when they are introduced into cement and concrete compositions. The use of additives of sols on the basis of compounds of sulfur and chromium not only accelerated hydration and hardening of cement in the early period, but also significantly improved the strength characteristics of cement stone. The received nanodispersed additives can be included in group of hardening-accelerating admixes of cement. The increasing of strength of a cement stone modified by sols of various compositions is a result of change of its structure. Electronic and microscopic analysis showed that use of sols of different composition as modifiers leads to compaction of microstructure of cement stone and formation of difficult compounds of sulfur and chromium with hydrated calcium silicates

Increased corrosion resistance of basalt reinforced cement compositions with nanosilica

Disperse fiber reinforcement is used to improve deformation and shrinkage characteristics, flexural strength of concrete. Basalt roving and thin staple fiber are often used as mineral fibers. The paper considers the problems of using thin basalt fiber produced by centrifugal-blow method. Evaluation of the corrosion resistance of basalt fiber as part of the cement matrix was performed. Nanodispersed silica produced by electron beam accelerator was used to increase corrosion resistance of basalt fiber