Nanosilica Modification of Epoxy Matrix in Hybrid Basalt-Carbon FRP Bars—Impact on Microstructure and Mechanical Properties

This article focuses on the effect of nano-silica on an epoxy matrix of hybrid basalt-carbon fiber reinforced polymers (FRP) composites. Usage of this type of bar continues to grow in the construction industry. The corrosion resistance, strength parameters, and easy transport to the construction site are significant parameters compared to traditional reinforcement. The research for new and more efficient solutions resulted in the intensive development of FRP composites. In this paper, scanning electron microscopy (SEM) analysis of two types of bars is proposed: hybrid fiber-reinforced polymer (HFRP) and nanohybrid fiber-reinforced polymer (NHFRP). HFRP, in which 25% of the basalt fibers were replaced with carbon fibers, is more mechanically efficient than basalt fiber reinforced polymer composite (BFRP) alone. In HFRP, epoxy resin was additionally modified with a 3% SiO2 nanosilica admixture. Adding nanosilica to the polymer matrix can raise the glass transition temperature (Tg) and thus shift the limit beyond which the strength parameters of the composite deteriorate. SEM micrographs evaluate the surface of the modified resin and fiber–matrix interface. The analysis of the previously conducted tests—shear and tensile at elevated temperatures—correlate with the microstructural SEM observations with the obtained mechanical parameters. This is a summary of the impact of nanomodification on the microstructure–macrostructure of the FRP composite.