Concrete reinforced with polymeric fibers: an approach by non-destructive techniques of ultrasonic pulse velocity and electrical resistivity

Abstract

The primary objective of incorporating fibers into concrete is to enhance its load-bearing capacity subsequent to cracking, thereby demonstrating its augmented toughness. Additionally, the incorporation of fibers into concrete has been demonstrated to enhance safety, utility, service life, performance, and durability of concrete structures, particularly in terms of crack control. Non-destructive testing are important tools for inspection and monitoring the integrity and service life of reinforced concrete structures. This research evaluated the mechanical performance, electrical resistivity (surface and bulk) and ultrasonic pulse velocity of concrete reinforced with polymeric fibers. Three different volumes (Vf ) of copolymer-based fibers (0.5%, 1.0% and 1.5%) were considered. The type of concrete with polyethylene/polypropylene-based fibers was also considered with a Vf of 1.0%. Tests were conducted to determine the material’s compressive strength, modulus of elasticity, and flexural tensile strength, as well as surface electrical resistivity, bulk resistivity, and ultrasonic pulse velocity. A detailed discussion of the results was conducted, with particular reference to statistical analyses, micromechanisms and correlated data. Consequently, an increase in Vf had a negative effect on the compressive strength and modulus of elasticity. As expected, there was a significant increase in the residual flexural tensile strength. An increase in Vf tends to reduce resistivity, particularly surface electrical resistivity, while the ultrasonic pulse velocity remains essentially unchanged. The optimum Vf of copolymer-based concrete of this study was determined to be 1%, and the performance of the three types of fibers studied (copolymerbased and polyethylene/polypropylene-based) was found to be “equivalent”. A comprehensive evaluation of the properties revealed that FRC (Fiber-Reinforced Concrete) exhibited distinct advantages, particularly with regard to its residual flexural tensile - strengths.