13th International Conference on Fracture June16–21, 2013, Beijing, China -6Table 4. Flexural strength of UHPCs in comparison with different steel fiber concentration (kg/m2) Normal curing Heat water curing UHPC Mix 14 day 28 day 14 day 28 day UHPC0 18.83 20.54 18.81 21.53 UHPC0.5 19.44 21.31 23.35 23.52 UHPC1.0 21.65 24.15 24.65 25.09 UHPC1.5 22.89 24.51 24.76 29.17 UHPC2.0 22.94 24.82 25.15 31.68 UHPC2.5 23.82 31.21 29.7 34.66 UHPC3.0 26.47 32.48 33.56 34.83 UHPC3.5 28.95 32.73 34.88 38.44 Figure 2. Photo prism UHPC2.5 after flexural test of crack extension and failure 3.2. Free Falling Test Figure 3 displays the photo of UHPC2.5 specimen in the free falling test setup for 6-meter high. After the 6-meter high free falling test, the UHPC2.5 specimen appeared three micro-cracks as shown in Figure 4. Table 5 indicates the surface cracks of UHPC2.5 specimen after the free falling test at three different heights. It was found from the free falling test result that UHPC2.5 specimen remains good condition on the surface at 2-meter height, but several micro-cracks appeared at 4-meter and 6-meter heights. It can be concluded that the surface micro-cracks of UHPC2.5 specimen increases substantially as height of the free falling test increases. 3.3. Loading Capacity Test Table 6 shows ultimate loading strength of UHPC precast specimens in comparison with different steel fiber concentration at 90 °C water curing. The result of the diameter of steel fiber comparison is that UHPC exhibits non-significantly enhanced ultimate loading strength compared at 90 °C water curing. For the ranges of steel fiber contents investigated in the study, both flexural strength and ultimate loading strength of the UHPC specimens increase as the percent steel fiber increase. The 2.5, 3.0 and 3.5% steel fibres by volume were chosen and used in UHPC precast products, after UHPC specimens were tested and finished on their performance evaluations. Compared with the ultimate loading strength of UHPCs in Table 6, the experimental result shows the UHPC containing up to 2.5% steel fiber content reached the predetermined effect at particular load level of 12-ton ultimate loading strength. Table 7 displays ultimate loading strength of UHPC2.5 precast specimens
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