Because they don't corrode, glass-fiber-reinforced plastic (GFRP) rebars were originally used for crack control in concrete structures exposed to aggressive environments. Examples are chemical plants, wastewater treatment plants, and marine structures. Now the plastic rebars are also being used in structural applications. Now the plastic rebars also are being used in structural applications. BAR MANUFACTURE AND PROPERTIES Manufacturers use a pultrusion method to make the bars, which are composites of thermosetting resins and a glass-fiber roving. The final rod composition is about 30 percent resin and 70 percent glass fiber. Tensile strength of the bars reportedly ranges from 70,000 to 170,000 psi and the tensile modulus of elasticity is in the range of 6 to 10 million psi. The GFRP bars cost about the same as epoxy-coated steel bars, but they are lighter and easier to lift and place, thus reducing handling costs.