Short Term Characteristics and Environmental Aging of Bio-Resin GFRP Tested in Tension and for Confinement of Concrete Cylinders

Abstract

Conventional fiber reinforced polymers (FRPs) require polymers such as epoxies that are not biodegradable, which have a significant impact on the environment. The first phase of the thesis aims at replacing conventional polymers with sustainable bio-polymers. The tensile mechanical properties of glass-FRP (GFRP) laminates using two types of organic furfuryl alcohol bio-resins extracted from renewable resources, such as corncobs, were investigated. Results are compared to control specimens fabricated using conventional epoxy resin. It was shown that by careful selection of viscosity of bio-resin, and type and dosage of catalyst, similar mechanical properties to epoxy-GFRP can be achieved. The second and third phases consisted of durability testing of the bio-resin GFRP. A total of 160 tension coupons and 81 unconfined and confined concrete cylinders wrapped with bio-resin-GFRP were studied. Conditioning was achieved by immersion of the specimens in saline solutions with 3% salt concentration, at 23, 40 and 55 degrees Celcius, for up to 300 days. Specimens were compared to epoxy-GFRP specimens aged in the same environment. Deterioration was quantified by tensile testing of the coupons and compression testing of the cylinders at various stages of exposure. The bio-resin-GFRP showed 33% less tensile strength retention than the epoxy-GFRP. The epoxy-GFRP and bio-resin-GFRP wrapped cylinders had the same un-aged confined axial compressive strength (fcc’), essentially a strengthening ratio (fcc’/fc’) of 2.24. After 300 days, the (fcc’/fc’) ratio retentions for the bio-resin-GFRP was 73% at all temperatures. Using the Arrhenius model, it was predicted that 61% retention in tensile strength of the bio-resin-GFRP and 65% retention of the compressive strength of wrapped cylinders would occur after 100 years in an environment with a mean annual temperatures of 10 degrees Celcius.