Rapid Strengthening of Reinforced Concrete Beams with Mechanically Fastened, Fiber-Reinforced Polymeric Composite Materials

Book excerpt: The U.S. military must often deploy to other countries where bridges may have insufficient strength for their heavy tactical vehicles. In recent years, fiber-reinforced polymeric (FRP) materials have emerged as a viable retrofit scheme for strengthening reinforced concrete bridges. However, because of stringent application requirements, long cure times, and climatic sensitivity, this technology has yet to prove feasible for military operations where time is often the most critical factor. Furthermore, Army operations are conducted under the broadest range of climatic conditions. For these reasons, the U.S. Army Engineer Research and Development Center has undertaken to develop a unique FRP application methodology utilizing powder-actuated mechanical fasteners (i.e., nails from a conventional carpenter's nail gun). This method shows great promise for military applications, since no substrate preparation or adhesive curing is required. Additionally, this method should work well in all but the most extreme environments. For this purpose, numerous laboratory tests have been conducted, and the results have been very promising. This report provides a detailed summary of the first 2 years of testing on this concept.