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1 Introduction
Self-compacting concrete (SCC), a new kind of high-performance concrete with excellent deformability and segregation resistance, was first developed in Japan in 1986. It is a special kind concrete that can flow through and fill the gaps of reinforcement and corners of molds without any need for vibration and compaction during the placing process ([1] Okamura, 1997; [2] Okamura et al. , 1993).
Self-compacting concretes are made using an innovative world renowned technology widely used in the vast field of construction. The increasingly extensive developments in the construction industry throughout the world along with the need for the application of concretes with such qualities as of the SCC, has lead to many studies on such types of concretes. SCC, requiring no consolidation work at site or concrete plants. SCC has high flow ability and a moderate viscosity, and no blocking may occur during flow; the concrete has to de-air by itself during casting. Several mix design methods for SCC were proposed by [3] Okamura and Ouchi (1999), Petersson and Billberg ([5] 1999) and [5] Sedran and de Larrard (1999). In Japan, SCC has been used for large office buildings and also for advanced types of extruded tunnels in combination with steel fibers ([6] Persson, 1998a, [7] b). Okamura's method conducts the cement paste and mortar test before moving onto evaluating properties of the superplasticizer (SP), cement, fine aggregate and pozzolanic material for saving the process from the redundancy of unnecessary testing, although its complicated procedure makes it difficult to apply to companies which manufacture the ready-mixed concrete.
In steel fiber reinforced self-compacting concrete (SFRSCCs), the most important factors affecting the concrete properties are type and vf of fibers. l /d ratio is important at mixing and replacement stages of normal concrete production ([8] ACI Committee 544, 1993). Generally, l /d aspect ratios of steel fibers used in normal concrete mix are varied between 50 and 100. But in SCC, the suitable l /d ratio is equal 50 because of flow ability and no blocking.
The most suitable vf values for concrete mixes are between 0.5 and 2.5 per cent by volume of concrete ([7] Persson, 1998b). The most important effect of vitreous, synthetic, carbon and steel fibers used...