Durability of Fiberglass Composite Sheet Piles in Water

The durability of fiberglass composite sheet piles in water was studied through the specimens cut from flanges and webs of pultruded sheet pile sections. The experiments were performed to evaluate the water absorption at ambient temperature in complete immersion, and its effect on the tensile properties and the freeze-thaw resistance of the saturated composites. The high temperature at 70°C was used to accelerate the tests, and 100°C (boiling water) to verify the state of saturation. The non-Fickian absorption behavior of the pultruded composites was modeled based on the Berens and Hopfenberg two-phase absorption theory to predict the long-term performance and the change in mechanical properties of saturated composites. The results indicated that the water absorption process of the pultruded sheet pile composites followed a combination of Fickian diffusion and polymeric relaxation. The percent absorption at saturation was about 1.72% for the flange and 3.11% for the web. The water absorption model predicted that saturation would be reached after 5.8 years for the flange and after 14.5 years for the web immersed in tap water at ambient temperature. The tensile strength was found to decrease initially with the increase in the percent water absorption, and finally stabilize at the state of saturation. On the other hand, there was no noticeable change in the tensile modulus of elasticity during the entire water-aging period. The saturated composites showed excellent resistance to freeze-thaw cycling from 4.4 to -17.8°C.