Reducing alkaline corrosion of basalt fiber in concrete

The article presents the results of studies on the development of fiber-reinforced concrete using composite binders and basalt fibers obtained in an experimental plasma reactor. To reduce the negative impact of Portland cement on the mineral fiber, composite binders based on Portland cement and fly ash were used in the study. To reduce the normal density in the composition of the binder, a polycarboxylate type superplasticizer was used in the work. The microstructure of cement stone was studied using SEM and IR-spectroscopy. The compressive strength was tested on cubes with an edge of 100 mm according to EN 12390-6, flexural strength - on prisms with a size of 100x100x500 mm according to EN 12390-3. The optimum content of fly ash (30 %) in the composite binder is evaluated, which allows to obtain high mechanical properties. It was revealed that the combined use of composite binder and fiber leads to an increase in compressive and flexural strength of fiber concrete. With the addition of fly ash, both hardening of the structure of the cement stone and a decrease in the alkaline effect of the basalt fiber binding on the surface are observed. Infrared spectroscopy of cement systems showed a change in the phase composition and a decrease in the basicity of the resulting calcium hydrosilicates upon addition of fly ash into the composition binder.