Durabiltiy characteristics of concrete columns confined with advanced composite materials

摘要

The durability performance of concrete columns confined with fiber-reinforced polymer composite (FRPC) sheets was studied. Columns were wrapped around with four different types of FRP composite wraps: two carbon (C1 and C5) and two glass (GE1 and GE2). Two types of epoxy matrix systems, Type A and B, were used. The confide and unconfined specimens were subjected to two environment conditions: room temperature, wet and dry cycling. For the wet and dry exposure, the specimens were placed in an environmental chamber in which they were subjected to 300 cycles of wetting and drying. Sea water washed for the wet cycles and hot air at 35 deg C average for the dry cycles. After every 30 cycles, pulse velocity and weight changes were measured. At the end of 300 cycles the stress-strain behavior of the samples was obtained in order to evaluate their strength, stiffness, and ductility, which were compared to the performance of the unconditioned samples (room temperature exposure). Results show that both epoxy systems produce similar results in the unconditioned specimens, with respect to strength, ductility, and failure behavior. However, specimens wrapped with glass fiber-reinforced polymer (GFRP) using Type A epoxy experienced no reduction in strength or ductility due to wet/dry exposure, whereas samples using Type B epoxy experienced reduction in both strength and ductility. Specimens wrapped with carbon fiber-reinforced polymer (CFRP) using either epoxy Type A or Type B exhibited no reduction in strength nor in ductility due to exposure.