الفهرس 
CHAPTER (1): INTRODUCTIONOnly 14 pages are availabe for public view
Abstract
This study aims to evaluate the efficiency of repair and strengthening reinforced concrete beams underwater using modern repair and strengthening materials. The main materials used in this investigation were glass fiber wrap, carbon fiber wrap, steel plate, carbon fiber laminate, and near-surface steel bars. Two techniques were used, externally bonded reinforcement and the near surface mounted system. In order to evaluate the bond between the concrete and the bonding materials, several bonding materials were used. The main variables in this study are repair and strengthening materials, repair and strengthening techniques, bonding materials, and environment of strengthening (air or underwater). All suggested repair and strengthening materials and techniques were performed on beam samples of dimensions 100*150*1000 mm. Three groups were used. The first was strengthened underwater while the other was strengthened in a laboratory environment, the third was repaired the beams that are loaded by 85% from load of control beam by epoxy injection. The results were obtained in terms of the initial cracking load, ultimate load, deflection values, tensile-strain values, and crack patterns. Test results showed that the using of carbon fiber wrap is the better as strengthening material under water and at air. As a bonding material, using polyurethane epoxy mortar ”kempoxy 165” is better than using polyester underwater while on air, using polyester is better than using polyurethane epoxy mortar ”kempoxy 165”. Also, the using of carbon fiber laminate ”Carbodur Plates” as a strengthening material in the air is the best in this study. The using of steel rebars as a near surface mounted reinforcement is the best as a strengthening material underwater in this study. When considering the bonding materials, using polyurethane epoxy mortar ” kempoxy 165”, then using polyester resin ”polyester” recorded the better values under water. On air, using polyurethane epoxy mortar ”kempoxy 165” then using Thixotropic epoxy resin ” Sikadur 30 ” is recommended for conventional strengthening processes. For repairing RC beams by cracks injection, using polyester resin ”Epoxy Injection Material” is better than polyester resin”Kemapoxy-103”