Study Of Mix Design And Mechanical Properties Of Fiber Reinforced Self-compacting Concrete

Fiber reinforced self-compacting concrete (SCFRC) is a kind of new composite material with good performances and wide application. In this paper, the SCFRC is blended with steel fibers and polypropylene fibers. So it combines the benefits of SCC in the fresh state and shows an improved performance in the hardened state due to the addition of the fibers. Compared with plain SCC, the crack resistance, ductility and impermeability of SCFRC are improved significantly. The parameters which affect the mix design and its optimization, strength, elastic modulus, and crack resistance of SCFRC are studied experimentally and theoretically in this paper. The details are about: Firstly, the effects of each component on the workability of SCFRC are analyzed in theory, and the methodology of desiralbe mix proportion with good filling ability and segregation resistance are founded. The methodology is that the correlations of steel fibres and the sand to total aggregate ratio, additional dosage of admixtures and fibre content can be established with the adjustment of the sand to total aggregate ratio, cementitious materials content, water content and dosage and type of chemical admixtures. Based on the analysis and comparison with the current mix design method and the maximal pacing desity method of SCC, optimal mix design method of SCC and SCPFRC are proposed, and the dependency of mix propotion design method on the experience is reduced to a certain degree. Secondly, the effects of mix procedure on the fresh stage workability of concrete mixtures are studied, and then the better mix procedure is recommended. It is that to add materials to the mixer step by step and mix the fibers in the end.The comparing the theoretic of mix packing density with the conventional design methodology of mix proportion, we find out the better method to design the mix proportion with the local materials through experiments. The best method is mixing materials step by step and mixing the fibers on the end. Finally, through analyzing the experimental dates of mechanical properties and crack resistance, we study the effect of fibers on these behaviors of SCC. We compare the effect degree of the steel fibers and the polypropylene fibers on these behaviors of SCC, and provide references to the later physically apply of the engineering.