Title:
Environmental Aging of Fiber-Reinforced Polymer-Wrapped Concrete Cylinders
Author(s):
Sachin Kshirsagar, Roberto A. Lopez-Anido, and Rakesh K. Gupta
Publication:
Materials Journal
Volume:
97
Issue:
6
Appears on pages(s):
703-712
Keywords:
column; composite construction; durability; polymer.
DOI:
10.14359/9985
Date:
11/1/2000
Abstract:
An environmental aging test protocol for evaluation of environmental durability of concrete wrapped with fiber-reinforced polymer (FRP) composites is proposed. The wrap material was made of E-glass and aramid woven fabric impregnated in an epoxy resin matrix. The effect of temperature, moisture, pH level, and freezing-and-thawing cycles on the mechanical properties of FRP-wrapped concrete was investigated. Aged FRP concrete hybrid cylinders were tested in compression after 1000, 3000, and 8000 h of environmental exposure. FRP composite coupons were exposed to the same conditions and tested in tension to identify the degradation mechanisms. Hygrothermal swelling of the FRP wrap was observed for the different aging conditions and led to a reduction in concrete confinement. The main cause of environmental damage in the hybrid system was the combined effect of moisture and elevated temperature on the tensile strength of the E-glass fibers. Residual hygrothermal strains in the FRP wrap and reduction in tensile strength of the E-glass fibers controlled the changes in the stress-strain response of the concrete-FRP hybrid system due to environmental aging. The following mechanical indicators were proposed to characterize environmental durability of FRP-wrapped concrete: 1) critical stress (onset of unstable cracking propagation) of concrete FRP cylinders; 2) retained compressive strength of concrete FRP cylinders; and 3) retained tensile strength of FRP coupons. The rate at which the retained compressive strength varied with time under the influence of the various environmental conditions was studied.