الفهرس 
Ageing and deterioration of concrete structuresOnly 14 pages are availabe for public view
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Abstract
The research reported in this thesis has two main objectives:-
(1) To investigate experimentally the viability and effectiveness of using cementitous materials such as silica fume, fly ash and marble powder as a replacement of cement and monitor its compressive strength, indirect tensile strength and flexural strength through 365 days also measuring its compressive strength after submersion in sodium chloride with different concentrations ratios 20%, 30 and 40% for different intervals 30 , 60 and 90 days besides measuring carbonation depth test, which was performed to show carbonation of each mix and to study thirty five different mortar and concrete mixes with a total of casting and testing 1750 cubes, cylinders. Twenty three reinforced concrete beams which reinforced with various composite materials. The concrete matrix was developed by employing two types of cements namely Ordinary Portland cement and High Slag cement. By products materials such as water cooled slag and air cooled slag were used as an environmental impact and comparing the obtained results with those manufactured with using dolomite and basalt aggregates.
(2) To investigate experimentally ferrocement beams reinforced with welded metal mesh , expanded metal mesh and fiber glass mesh for durability reason with different types of core materials such as UPVC pipes and light weight bricks to be used as a viable alternative to the conventional reinforced concrete beams. The flexural behaviors of 23 reinforced beams subjected to four lines loading until failure and cracking behavior were was Chapter 8 Conclusion and Recommendations for Further Studies determined extensively. An analytical model based on the ultimate strength theory suitable for mathematical calculations was developed to determine the ultimate strength and mode of failure of the developed beams. There was a good agreement between the results obtained from these theoretical models and their respective experimental results. This agreement verifies the validity of the model for determining ultimate strength of the proposed beam system. 8.2 Conclusions 8.2.1 Concrete and Mortar mixes The test results of the current experimental program showed that:-
1) Using 10% silica fume as cement replacement in ordinary Portland cement mortars increased compressive strength by 10% within a year’s time. Employing 10% silica fume with 30% fly ash replacement of cement increase compressive strength by approximately 10 % after 28 days and there is continuous strength gain of strength with age as result of reaction between SiO2 and free lime produced during the process of hydration of cement. Superior high strength could be reached at long time.
2) Using 10% marble powder as cement replacement increased compressive strength by 23% at 28 days and 8.5% in a year’s time, while using 10% marble powder with 30% fly ash gives the greatest compressive strength of all ordinary Portland cement mortars mixes and reached 37 MPa at 28 days and 61 MPa at one year which is 26% higher than that of control mix.