The use of GPR to investigate the effect of steel fiber distribution on the mechanical behavior of FRC

Abstract

The present work focuses on the steel fiber distribution in self-consolidating concrete short beams. The objective is to assess the feasibility of the ground penetrating radar (GPR) in evaluating the homogeneity of fibers within concrete materials, for use in testing laboratories to study the modes of placing and compaction employed for preparing specimens during quality control or material development. Self-consolidating concrete beams were cast, tested, and evaluated. A GPR survey employing a concrete scanning system with a shielded 1.2 GHz center frequency was performed on self-consolidating casted short beams just before a monotonic four-point bending test was carried out. After failure, a representative short beam was cut and the resulting slices were photographed to obtain the position and distribution of the steel fibers. Results were processed using dedicated software and an integrated analysis was accomplished. The digital and processed images correlated well with the GPR mappings in a single radar trace mode. In particular, the GPR amplitude provides information on the steel fiber density that was used as reinforcement in concrete specimens.