الفهرس 
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Abstract
Cracking is an essential feature of the behavior of concrete structures. Even under service loads, concrete structures are normally full of cracks. Clearly, cracking should be taken into account in predicting ultimate load capacity as well as behavior in service. To fracture mechanics specialists, it appears natural that concrete structures should be designed according to fracture mechanics. Yet, none of the existing code provisions are based on fracture mechanics. Traditional concrete has attracted significant attention in previous research, but modern concrete types has not received as much attention, such as Geopolymer Concrete and Fiber Reinforced Concrete. Identification of fracture parameters of fiber geopolymer concrete (FGPC) is currently a hot research area. Fracture mechanics analysis was tried, and was found to yield predictions that deviate from measurements. Fracture mechanics is the field of mechanics concerned with the study of the propagation of cracks in materials. It uses methods of analytical solid mechanics to calculate the driving force on a crack and those of experimental solid mechanics to characterize the material’s resistance to fracture. Experimental analysis of fifty-four notched beams will be conducted in which several variables including binder type, notch height, reinforcement ratio, fiber ratio and binder replacement ratio will be taken into consideration. All tested notched beams with overall thickness equal to 150 mm, width equal 100 mm and span equal 1000 mm was investigated in three-point bending test. In this study, heat cured alkaliactivated fly ash based geopolymer concrete with polypropylene fibers and fiber cement concrete are the main type of concrete Experimental program plans were divided into three main variables, the first variable deals with comparing the fracture parameters and notched beam behavior under loading between heat-cured alkali-activated fly ash based geopolymer concrete and the cement concrete with polypropylene fiber. According to of using fly ash as a replacement binder material in cement concrete, the fracture parameters investigated by compression with the traditional cement concrete. The second variable deals with testing notched beams made of heat-cured alkali-activated fly ash based geopolymer concrete with various cement replacement ratios (0%,20%,30%, and 50%). The third variable deals with testing specimens of notched beams of heat-cured alkali-activated fly ash-based geopolymer concrete with various fiber ratios (0%,0.5%, and 0.75%). This thesis also presents a numerical analysis for fracture mechanics parameters according to linear elastic fracture mechanics (LEFM) formulae. It was proven that there had been a great discrepancy among the predictions of theoretical LEFM formulae for fracture toughness, fracture energy and characteristic length. R-curves of various specimens depicted crack propagation at various stages of loadings where stable crack propagation was observed for specimens reinforced by 0.17% reinforcement ratio and larger. the “work of fracture”-by definition- the formula is the most reliable to calculate the fracture energy as the nonlinearity is associated with the behavior of FGPC.