Nano- and Micro-Modification of Building Reinforcing Bars of Various Types

Abstract

Fiber-reinforced plastic (FRP) rebar has drawbacks that can limit its scope, such as poor heat resistance, decrease its strength over time, and under the influence of substances with an alkaline medium, as well as the drawback of a low modulus of elasticity and deformation. Thus, the aim of the article is the nano- and micro-modification of building reinforcing bars using FRP rebars made of basalt fibers, which were impregnated with a thermosetting polymer binder with micro- or nanoparticles. The research discusses the major results of the developed composite reinforcement with the addition of micro- and nanosized particles. The microstructure of FRP has been studied using scanning electron microscopy. It was revealed that dispersion-strengthened polymer composites with the inclusion of microsilica (SiO2) and nanosized aluminum oxide (Al2O3) particles have a much higher modulus of elasticity and strength when compared with the original polymer materials. In the course of the experiment, we also studied the retained plastic properties that are characterized by the absence of fragility. However, it was found that the high strength of materials was attained with a particle size of 10–500 nm, evenly distributed in the matrix, with an average distance between particles of 100–500 nm. It was also exhibited that composite reinforcement had improved the adhesion characteristics in comparison with both steel reinforcement (1.5–2 times, depending on the diameter), and with traditional unmodified FRP rebar (about 1.5 times). Thus, the use of micro-/nanosized powders increased the limit of the possible temperature range for the use and application of polymeric materials by almost two times, up to 286–320 °C, which will undoubtedly expand the range of the technological applications of products made of these materials.