Title: Investigation of S-2 Glass/Epoxy Strands in Concrete

Author(s): Rajan Sen, Daniel Mariscal, and Mohsen Shahawy

Publication: Symposium Paper

Volume: 138

Issue:

Appears on pages(s): 15-34

Keywords: diffusion; durability; epoxy resins; fiber reinforced plastics; glass fibers; pretensioning; rupture; scanning electron microscope; salt water; stresses; Materials Research

DOI: 10.14359/3857

Date: 9/1/1993

Abstract:
A comprehensive durability study of S-2 glass-epoxy pretensioned beams exposed to wet-dry cycles in 15 percent salt solution indicated a complete loss of effectiveness within 3 to 9 months of exposure. Paper presents results of subsequent follow-up investigations to identify the cause of this deterioration and also to examine practical measures that could be used to prevent its occurrence. The analysis of the test results suggests that the most likely cause of failure was diffusion of hydroxyl ions from the concrete pore solution through the resin. This is supported by SEM micrographs of the failed beam. While these conclusions are valid only for the S-2 resin, diffusion is also likely to be a characteristic of other types of resins, e.g., vinylesters and polyesters. This makes long-term protection of glass fibers in concrete problematic.