Paper by TOUTANJI ZHANG from ISCR 9th 2004 Instanbul Turkey
During recent years studies have reported the crises involving deficiency or deterioration of a considerable portion of the Nation infrastructure. Many concrete structures need repair and strengthening for several reasons, such as expired design life, changes in functionality, damage caused by mechanical actions and environmental effects, more stringent design requirements, original design and construction errors. Innovative techniques for rehabilitation are expected, because of the prohibitive cost of replacing all of the substandard structures. Externally bonded fiber reinforced polymer (FRP) sheets/laminates is now recognized as a technically practicable and efficient method to strengthen and upgrade structures with damage, degeneration and functional inadequacy. This paper focuses on investigating the flexural behavior of steel reinforced concrete beams externally bonded with FRP laminates using both organic and inorganic epoxy matrices. A total of eight beams was tested during the experiment: two control beams and six reinforced with CFRP/epoxy sheets. Double steel reinforcement, different reinforcement ratios, and two types of epoxy matrix (organic and inorganic) were used to simulate a variety of situations in practice. All specimens were subjected to four-pointbending test under load control. The effect of the type of reinforcement, the type of resin (organic and inorganic) and the number of fiber layers was studied. Loads, moment, maximum crack widths, mid-span deflections and mid-span strains were measured throughout loading. Results showed that organic and inorganic epoxy matrices exhibited the same effects on the moment-strain relationship; however, all the organic beams were failed due to fiber delamination whereas the inorganic beams failed due to fiber rupture.