石粉含量与钢纤维长度对机制砂超高性能混凝土性能的影响

Effect of Stone Powder Content and Steel Fiber Length on Properties ofManufactured Sand Ultra-High Performance Concrete

为利用机制砂作细集料制备一种低成本的超高性能混凝土(UHPC),研究了石粉含量(5%、7%、10%、12%、15%)与3种长度的钢纤维及其2种钢纤维混杂对花岗岩机制砂UHPC的工作性能和力学性能的影响规律,并与河砂UHPC进行了对比。结果表明,机制砂UHPC的流动性低于河砂UHPC,且随石粉含量的增加而显著降低,机制砂UHPC的抗压强度、抗弯拉强度和弹性模量随石粉含量的增加呈先增大后降低趋势,当石粉含量≥10%时,机制砂UHPC的各项力学性能高于河砂UHPC。在钢纤维总体积掺量保持2%不变情况下,随钢纤维长度增加,UHPC的流动性降低,力学性能增大;当1%的长度13 mm平直钢纤维和1%的长度20 mm端勾钢纤维混杂时,机制砂UHPC的各项力学性能最佳。

In order to prepare a low-cost ultra-high performance concrete(UHPC)using manufactured sand as fine aggregate,the stone powder content(5%,7%,10%,12%,15%)and three types of steel fibers and the influence of the two types of steel fiber mixing on the working and mechanical properties of granite manufactured sand UHPC were studied and compared with that of river sand UHPC.The results show that the fluidity of the manufactured sand UHPC is lower than that of the river sand UHPC,and decreases significantly with the increase of the stone powder content.The compressive strength,flexural tensile strength and elastic modulus of manufactured sand UHPC increase first and then decrease with the increase of stone powder content.When the content of stone powder≥10%,the mechanical properties of manufactured sand UHPC are higher than river sand UHPC.Under the condition that the total volume of steel fiber is maintained at 2%,as the length of the steel fiber increases,the fluidity of UHPC decreases and the mechanical properties increase.When 1%of the length is 13 mm flat steel fiber and 1%of the length 20 mm end hook steel fibers are mixed,the mechanical properties of the manufactured sand UHPC are the best.