Bond Variability of Glass-Fiber-Reinforcing-Plastic Reinforcement in Concrete

摘要

This report summarizes an experimental program that investigated the bond variability of glass-fiber-reinforced-polymer (GFRP) reinforcement in concrete. The variables in the study were manufacturer (Marshall Industries Composites, Inc. M1 and Corrosion Proof Products/Hughes Brothers M2), bar size (No. 5 and 6), cover (2 and 3 bar diameters), and embedment length (10 through 47 in.). Tensile tests were also performed on the GFRP rebar for comparison to bond tests that exhibited bar failure. Eighty-four inverted half-beam bond specimens were tested while monitoring load, loaded-end slip, free-end slip, cracking, and acoustic emissions on the embedded bar and concrete. Three to six replicate tests were conducted for each set of variables. The results of each test within a series were examined to investigate the relative variability with respect to the failure types. The M1 rebar was observed to rely primarily on mechanical interlock to develop bond strength. This conclusion was based on investigations of the rebar surface condition, bar deformation geometry, slip curves, AE results, crack patterns and forensic investigations. Additionally, the ultimate loads for the bond tests with the Ml rebar were affected by changes in embedment lengths but did not vary for tests with 2 and 3d(b) cover. Overall, the M1 rebar had coefficients of variation (COV) of 14.3 and 8.9% for bond tests that exhibited bar failure and tensile test bar failures, respectively. The bond tests that failed in concrete splitting had COVs from 5.2 to 5.9%.