Experimental Study on the Effect of Mixing Steel Fibers of Different Lengths on the Performance of UHPC
In order to effectively reduce the cost of steel fibres in ultra-high performance concrete(UHPC),a comparative study of the basic working and mechanical properties of UHPC was carried out by mixing different lengths of steel fibres.The results show that:the length of steel fibre has a certain effect on the degree of expansion of UHPC,in general,the degree of expansion of the long fibre mixing group is smaller than that of the short fibre mixing group,and the amount of steel fibre mixing has a greater effect on the degree of expansion compared with the length of steel fibre;hot water curing can promote the rapid reaction of calcium hydroxide to generate a higher strength of the C-S-H gel substance in UHPC,and the mechanical strength of the UHPC in hot water curing for 3 d is significantly higher than that of the standard curing.The mechanical strength of UHPC in hot water conditioning for 3d is significantly higher than that of standard conditioning for 28d;the compressive strength of UHPC with 8 and 20 mm steel fibres in hot water conditioning is the highest,the flexural strength of UHPC with 16 and 20 mm steel fibres in hot water conditioning is the highest,and the compressive and flexural strengths of UHPC with 16 and 20 mm steel fibres in standard conditioning are the highest;the comprehensive performance of UHPC was calculated through the hierarchical analysis,and the calculation and analysis of UHPC performance were found to be the highest with the mixing scheme of 13 and 20 mm or 16 and 20 mm.It is found that the comprehensive performance of UHPC with 13 and 20 mm or 16 and 20 mm mixing scheme can exceed the comprehensive performance of UHPC with13 mm long steel fibre single mixing3%,and the optimization of mixing can reduce the production cost of UHPC material by 600～700 RMB/m3.
ultra high performance concretesteel fiber lengthmixingchromatography analysis methodcomprehensive performance
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