الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Underwater concrete (UWC) is a special type of high performance concrete used in the past, present, and in the foreseeable future as long as there is need to construct bridges with foundations in soil with high water levels and repair for hydraulic structures. Successful casting of UWC can be achieved if sufficient attention is paid to the concrete mix design and placement techniques. Reduction in quality of the hardened concrete is mainly due to the washing out of cement and fine particles as well as segregation of coarse aggregates upon casting in water. The problem of investigation of underwater concrete under hydrostatic pressure remains unresolved due to the lack of the appropriate testing equipment. Therefore, the objective of this study is to evaluate underwater concrete properties using a new technique in Egypt. In brief, the work of this thesis has been performed to investigate different fresh and hardened properties of underwater concrete. To achieve the objective of this work, three groups of underwater concrete with a total number of 58 mixes were prepared and investigated. group One: mix containing crashed stone as a coarse aggregate, group two: mix containing local steel slag as coarse aggregate and group three: mix containing gravel as coarse aggregate. The test program was arranged to determine the effect of antiwashout admixtures, cement content and type, coarse aggregate type and size, the ratio of fine to coarse aggregate, water to binder ratio, high range water-reducing dosage, fine materials type and content. Two types of cement were used. These types are ordinary protland cement and sulphate resistant cement. Three types of coarse aggregate were used. These types are steel slag, crashed stone and gravel. Steel slag waste as a substitute of crashed stone and gravel in construction materials would resolve the environmental problems caused by the large-scale depletion of the natural sources. Locally produced fine materials as silica fume and limestone powder with concrete varied from 0.0 to 30% by weight of cement were used. Antiwashout admixtures, with a dosage varied from 0.0 to 0.5% by weight of cement, were used. High range water-reducing dosage which meets the requirements of ASTM C494 types G and F, with a dosage varied from 2 to 4% by weight of cement, were used. The water to binder ratio varied from 0.35 to 0.5 depending on the content of cement and fine materials. UNDERWATER CONCRETE ABSTRACT vii In the fresh state, the tests are slump flow, slump flow time at T50cm, V-funnel test (Flow Time), L-box test (Blocking Ratio), air content, GTM screen stability (segregation resistance) and washout resistance using two test methods based on different principles. The first method is the two key documents produced to date are CRD-C 61-89A test method for determining the resistance of freshly mixed concrete to washing out in water and CRD-C 661-06 specification for antiwashout admixtures for concrete, and the second method is the pressurized air tube which has been manufactured for this research and developed to simulate the effect of water pressure on washout resistance of underwater mix. The results of hardened properties test were compared to concrete casted underwater with that casted in air. Test results indicated that the use of an AWA facilitates the production of UWC mix with the added benefit of lower washout resistance. New technique of simulating pressurized UWC is reliable for detecting UWC properties. Adding AWA (0.3–0.4%) by weight of cement makes all mix acceptable according to Japanese Society of Civil Engineers. The guideline of washout resistance which meets 70% residual compressive strength were 12.2 and 9.4 that can indicated the maximum washout loss and pH respectively . Almost all the concrete mixtures attained the minimum relative compressive strength recommended by Japanese society of civil engineering.