الفهرس 
Chapter (1) IntroductionOnly 14 pages are availabe for public view
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Abstract
1-Introduction: The newly world draws attention to a new type of concrete called ultra-high-performance concrete (UHPC) and is purely one of the new classes of concrete. It is also called reactive powder concrete (RPC). UHPC is one of the breakthroughs in the 21st century in the field of concrete technology. It played a great role in the concrete research. It achieved high results of toughness, bonding strength, durability, compressive strength, long-term stability, toughness, high resistance of split tensile strength, flexural strength and improved resistance against chemical attacks and also against fire and corrosion. The compressive strength, the flexural strength and the young’s modulus are 150:200 MPa, 30:50 MPa and 50:60 GPa respectively in UHPC. For the previous superior properties of UHPC, it is considered a good material in the field of retrofitting techniques and suitable in rehabilitation of buildings and construction high buildings. UHPC is the best concrete used in solving highway infrastructure deterioration, repairing constructions and building structures with long span, thin section and light weight. It is widely used in bridge girders, precast structures, arch buildings, piers, marine buildings and constructions in aggressive-environments. Increasing compressive strength became a basic requirement and to do that, reducing the water to cement ratio and using superplasticizer became necessary. UHPC is a composite material which consists of Portland cement, quartz sand, silica fume, super plasticizers, steel fibers and low ratio of water. UHPC was developed by the French Company Bouygues in 1994 and the first application was in 1997 in Canada by Sherbrooke Pedestrian Bridge. 2-Research Scope: Study the effect of using different ratios of silica fume, crushed quartz powder, steel fibers and different aggregate size on the mechanical properties and fracture mechanics of ultra-high-performance concrete. 3-Research Objective: Produce ultra-high-performance concrete using available materials such as crushed quartz powder, silica fume, steel fibers and cement. Moreover, study the effect of used materials on the mechanical properties and fracture mechanics of ultra-high-performance concrete. ANOVA test was used to investigate if survey or experiment results are significant or not. (ANSYS) was used to obtain KIc by using failure load which was obtained from the fracture mechanics test. 4-Summary of Study: the results showed that it’s possible to produce ultra-high-performance concrete with compressive strength 168.2 MPa and flexural strength 36.9 MPa by using fine sand with maximum nominal size 0.6 mm containing 50% natural sand with 50% limestone, 0.25 silica fume by cement weight, 2% steel fibers by concrete volume, 900 Kg/m3 cement and 0.2 quartz as a partial replacement of fine sand by weight.