EXPERIMENTAL INVESTIGATION OF THE MECHANISM OF DETERIORATION OF FRP REINFORCEMENT FOR CONCRETE

FRP specimens made of carbon and glass fibers were custom-made in the laboratory following a procedure similar to that used in actual manufacture of a FRP grid. They were exposed to water, saline and alkaline solutions, and air under a tensile load of 50% or 30% of their ultimate strengths. A total of 120 specimens were tested, 96 made of carbon fibers and the rest of glass. Condition of the specimens was examined at 45, 122 and 370 days from beginning the exposure by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. The glass fiber specimens exposed to an alkaline solution failed even before the first series of examinations (45 day) could be carried out. The carbon fiber specimens exposed to the alkaline solution showed signs of physical damage in the form of etching, cracking and even spalling of the resin.