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Ultra high performance concrete (UHPC) uses large quantities of steel fiber, silica fume, filler and superplasticizer for a low water-to-binder ratio (W/B). Despite of exceptional mechanical performances, UHPC exhibits increased viscosity due to the adoption of silica fume and its fabrication cost is costlier than ordinary concrete because of the use of large quantities of expensive materials. Following, this study evaluates the mechanical properties of 180MPa-UHPC using zirconium silica fume (Zr) instead of silica fume with respect to the quantity and type of superplasticizer (SP) and the size of filler. The results reveal that the Zr-UHPC using W/B of 20%, 100% of Zr, amount of SP-L of 2 to 3% and 4 μm-filler with steel fiber in 1.5 vol.% can develop better fluidity than the traditional mix composition using silica fume and secure a compressive strength higher than 180 MPa. In addition, the proposed mix composition is shown to enable a reduction of the fabrication cost by 33% compared to traditional UHPC.

In this study, the bleeding tests were performed to investigate the effects of cement paste(w/c=0.42) on bleeding through varying the number of strand and the diameter of cylinder. The test variables were specified by differing the diameter of cylinder and the number of strand. The bleeding test was performed with respect to all diameter parameters by with or without strand. In addition, the number of strands were specified at four levels, 0, 1, 2, and 3 EA in case of 50 mm cylinder. In case of without strand, the bleeding rate was determined at low level under 2%. Moreover, all of the specimens had similar value in the measurement error. In case of with strand, maximum bleeding rate was 10%. As the diameter of cylinder decreased, the bleeding rate was decreased. The bleeding rate was altered rapidly in between 50 to 100mm of diameter. Even though bleeding rate was increased according to the increase in the number of strand, these tendency for bleeding rate was negligible with the measurement error.

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