Ribbed glass fiber reinforced plastic rebar embedded in concrete - an experimental study

The experimental program developed in this work aims at investigating the bond behavior of glass fiber reinforced plastic embedded in concrete. Different types of surface treatment were applied to the smooth rods in order to enhance the bond with concrete. Firstly, the rods were machined using a lathe and a grinding stone to create lugs with different configurations. The experimental results indicate that the bond strength is highest when the failure mode is a combination of two mechanisms: shearing off of the concrete lugs and that of the FRP lugs. With regard to the variation of rib width, the friction and interlock forces have a greater influence on bond strength. With respect to the height of the rib, the variation of internal diameter does not affect significantly the bond strength. Secondly, the machined rods were coated with sand fixed with a thin layer of epoxy resin. The incorporation of the sand on the surface increases the bond strength compared with the results obtained without sand.