الفهرس 
PROPERTIES OF HARDENED SCCOnly 14 pages are availabe for public view
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Abstract
Self-Compacting Concrete (SCC) is an innovative concrete that does not require vibration for placing and compaction. It is able to flow under its own weight, completely filling formwork and achieving full compaction, even in the presence of congested reinforcement. Due to its advantages SCC seems to be very promising material for concrete construction. Research investigations on various aspects of SCC have been reported worldwide. However, there is an obvious paucity of information on time-dependent properties (e.g. creep and shrinkage) of SCC. Such properties are very vital in structural design of concrete members. The possible errors in the estimation of these properties can cause a serious problem in the design of concrete structures such as pre-stressed concrete members. Thus, there is a great need to evaluate the mechanical and physical properties as well as time-dependant properties (creep and shrinkage) of SCC; therefore, correct values of these properties can be used in structural designs of concrete members. The main aim of this research work was to generally improve and amplify our knowledge of the time-dependent behavior of SCC (Part-1) as well as its pore structure properties (Part-2). The effects of many factors that would affect the time-dependent behavior of SCC were intensively investigated. Time-dependent behavior of SCC was investigated in terms of its mechanical properties and time-dependent deformations. Mechanical properties were determined in terms of compressive strength and modulus of elasticity tests, which were carried out at different ages. Time-dependent deformations were expressed in terms of shrinkage and creep in compression. In this research program, the main parameters include SCC type, w/c ratio, S/A ratio, curing period, stress-to-strength ratio, and the relative humidity. The dimensions of concrete specimens used for measuring creep and shrinkage strains were 100x100x400 mm. Compressive strength was measured on cubes (150x150x150 mm) according to ECP. Modulus of elasticity was measured on cylindrical specimens (150x300 mm) according to ASTM C469 test method. The specimens moulds were removed after 24 hours after casting and the specimens were cured in water until testing. A pair of gauge points was applied on each surface, except the casting surface and its opposite side. The concrete specimens were dried and loaded at age of 28 days after casting. However, to study the effect of curing period for concrete at loading, some of the specimens were loaded at two additional loading ages, i.e. 3 and 7 days. For creep specimens, the adopted loading level was about 30% of the concrete strength at loading. However, to study the effect of stress-to-strength ratio some of the specimens were loaded at additional loading levels of about 20% and 40% of the concrete strength at loading. Just before the test, three cubes were tested to obtain the compressive strength of concrete and to determine the loading level. Pore structure of SCC was investigated in terms of total pore volume, total pore surface area, porosity, and pore size distribution. In this part of the study, the effect of SCC type as well as w/c ratio on the pore structure properties of SCC was investigated. Mortar mixtures were used with the same concrete mixtures proportions, excluding gravel, to investigated pore structure of SCC. Based on the experimental results obtained from the present research program, more information about several aspects of time-dependent properties as well as pore structure of SCC were gained. The experimental results were used to develop and propose prediction formulations to estimate the time-dependent behavior of SCC.