Glass fiber reinforced concrete (GFRC) is a cement based composite product which is reinforced with glass fibers. GFRC cladding panels are increasingly being used in the United States and other countries. The expanding use of GFRC panels should be supported with sufficient information on long-term properties. Although information on long-term strength is available, relatively little data on long-term ductility are available. The ability of the panel to withstand forces and deformations may depend on its strength but also on its ductility. Tests were conducted to evaluate long-term properties of three different GFRC composites. The results of these tests are evaluated with an emphasis on quantifying toughness. The results of these tests and analyses are described in this paper. Two toughness indices: TI (aging) and TI (improvement) are proposed as methods to quantify the ductility of GFRC panels. Both of these indices can be evaluated from flexural tests currently being performed for quality control of GFRC.
