Resistance of concrete specimens strengthened with FRP sheets to the penetration of chloride ions

Abstract EN

Externally reinforced concretes with FRP sheets are often in contact with moisture and temperature cycles that reduce the expected durability of the system.

This study intends to examine the durability of concrete specimens strengthened with FRP sheets under accelerated laboratory conditions that mimic harsh environmental conditions and simulate the penetration of chloride ions through the FRP.

In this study, three groups of specimens were examined.

Group I includes eleven concrete prism beams.

One specimen was neither strengthened nor corroded to serve as a reference.

Two specimens were corroded and not repaired.

The remaining eight beams were repaired with FRP sheets and then corroded.

Four strengthened beams were fabricated in group II to simulate a post-strengthening technique.

Furthermore, Group III consists of twenty-three cylindrical specimens wrapped with FRP sheets.

Concrete specimens were manufactured in the laboratory and flexural strengthened with FRP layers in four schemes, and one and two layers of GFRP and CFRP.

Moreover, several beams of group I were subjected to higher temperatures to simulate the thermal effect expected in field conditions.

Test results show that complete wrapping of concrete specimens by FRP sheets reduces chloride ion penetration up to 70 percent.

Moreover, results indicate that immersion in salt water, at higher temperatures, caused considerable degradation of ultimate load capacity of RC beams by 13.6 percent.

However, FRP confined concrete beams showed better performance under these conditions and their ultimate strength increased up to 8.1 percent.

Significant differences were detected in the behavior of the systems strengthened with GFRP and CFRP, probably due to degradation of GFRP sheets under continuous immersion.