Evaluation of fiber content in GFRP bars using digital image processing

Abstract The tensile strength of a fiber reinforced polymer (FRP) bar is directly related to the percentage of fibers measured by weight or volume. Recognizing the increasing number of different commercially available FRP bars, the implementation of precise methods for quantification of constituent fractions is of high importance to determine physico-mechanical properties. In this study, the fiber and resin matrix contents of four commercially available glass FRP (GFRP) bars were evaluated by implementing micrograph analysis of representative cross-sectioned specimens and compared to a conventional resin matrix separation method. The micrograph analysis was performed through digital image processing (DIP) of scanning electron microscope (SEM) images, while the conventional method was achieved by applying the standardized burn-off resin technique (ASTM D2584-18 ). The fiber volume fractions obtained from the DIP method were converted to weight fraction through constituent relationship equations. Comparable weight fraction values were obtained from both methods. However, the DIP method has the capability to provide additional microstructural information.