Leaning on Glass: Industry Pushes for the Use of Glass Fiber-Reinforced Rebar

This article reviews current knowledge and practice in the use of glass fiber-reinforced polymer (GFRP) rebar in bridge decks to extend deck life by eliminating the typical failure mechanisms associated with conventional or coated steel rebar. GFRP bars have been used as concrete reinforcing for most of the last decade. More than 75 bridge decks have been built with GFRP in the U.S. and Canada alone. All are performing successfully to date. Several key documents now can be used as references for these materials. The American Concrete Institute Committee 440 Document, 440.IR-06 “Guide for the Design and Construction of Concrete Reinforced with FRP Bars,” is one. An important one for the American bridge design community is “AASHTO LRFD Bridge Design Guide Specifications for GFRP Reinforced Concrete Decks and Deck Systems.” GFRP bars’ use is straightforward. What is important is to ensure that they have met key tests under methods outlined by the American Concrete Institute. While the bars have been used in decks, railings, abutments, and approach slabs, the amount of them in each bridge varies widely. The biggest change when using GFRP is that it is linear elastic up to failure and does not yield. Design guidelines suggest very conservative use of them because they are so new. There are also minor differences during concrete pours because they tend to be lighter than conventional steel rebar. However, there is no new training required, and they can be procured with the same procedures.