الفهرس 
ACKNOWLEDGEMENT
FRP STRENGTHNING SYSTEM COMPONENTOnly 14 pages are availabe for public view
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Abstract
as bonding agents for CFRP uni direction texture. Many items were investigated to enhance the bond strength and decrease slippage in strengthening system and also to improve the bond between bonding agent and concrete interface. In order to evaluate each parameter effect on strengthening system efficiency Single shear test and beam test with actual scale have been carried out in this thesis. Also the flexural behaviour of FRP-strengthened RC beams using cement-based bonding materials has been studied.
Part 1: Single shear test
Plain concrete prisms with low compressive strength (20 N/mm2) have been used in single shear test. This low compressive strength was chosen to act as the original weak concrete members. Two main groups of cement base bonding agents were investigated in this test (Portland cement and Grout matrix’s). Three main items were looked for in part1.These items were as follow:-
Item1: mixture components; it was represented in (cement content, using silica fumes & using short metallic fibers).
Item 2: CFRP sheet modification; represented in either: a) making holes in CFRP sheets -hence the cross section area of the CFRP sheets were kept the same as all other specimens- or b) impregnate the CFRP sheets in latex-base adhesive material just before using).
Item 3: the strengthening technique; which was represented by both the bonding agent layer thickness & Curing pressure; (it is a pressure done with a specific value just after applying the strengthening on the concrete prism along 24 hours).
Single shear test results showed that the cement-base matrixes were a very good alternative for epoxy as a bonding agent. Applying Curing pressure; almost double the bond strength and prevent the failure from occurrence in the surface interval between bonding agent / concrete interface, using latex and making holes in the CFRP sheet enhance the penetration of the bonding agent within CFRP sheet. Portland cement gave higher results than grout. Using silica fumes and even increasing the cement content; both have a negative effect on bond strength.
Part 2: Beam test
In order to assess the efficiency of cement base material as bonding agent four point bending test have been carried out on 6 RC beams; the first beam (control beam) without any strengthning and the other 5 beams flexurley strengthned with externaly bonded CFRP uni direction sheet using cement based material as a bonding agent. The structural behaviour of strengthened beams have been analysed at both serviceability and the ultimate conditions.
Based on single shear test results C40- mixture with cement content of 400 kg/m3 and without any other additives - was chosen as bonding agent in beam specimens. The studied parameters included the following points:
1- Fiber strengthening ratios (ρf = Af/bh). 2- Curing pressure.
3- Latex-base adhesive. 4- using nailes as shear connectors.
Beam test results showed that using cement base bonding materials with CFRP uni direction fabric in flexural strengthening of RC beams, have a certain positive effect on the terms belonging to raising the crack load and steel yield load. But it hasn’t noticeable effect on ultimate load. Curing pressure is promising technique; hence curing pressure raises both the crack load and yield load by about 105.13% and 16.07% respectively over that of the control beam. Using latex improving the ability of CFRP texture for impregnation with cement base materials which was reflected by raising both crack and yield load. Although doubling number of layer (amount of fiber) raise both crack and yield load but the relation between the number of layers and the raising occurred in loads was not linear. Curing pressure and using latex was more effective than using nails as shear connector.