Uniaxial Tensile Properties and Damage Constitutive Model of UHPC with Coarse Aggregate
The effects of coarse aggregate usage amount and steel fiber characteristics including content,type and hybrid on tensile properties of ultra-high performance concrete with coarse aggregate(CA-UHPC)were studied through uniaxial tensile test.The failure mechanism of CA-UHPC and the interaction mechanism of coarse aggregate and steel fiber were revealed.The results show that the weak interface and spatial barrier caused by coarse aggregate weaken the toughening effect of steel fiber.The tensile properties of CA-UHPC decrease with the increase of coarse aggregate content,so the recommended amount of coarse aggregate should not exceed 450 kg/m3.Increasing fiber content can improve the tensile properties of CA-UHPC,in which the toughening effect of straight steel fiber is more stable.When 1.0%straight and 1.0%end-hooked steel fibers are mixed,the fibers are well matched with coarse aggregate and the effective utilization rate of fibers reaches 25.4%,which indicates that the synergistic toughening effect of hybrid fibers is fully exerted.Finally,a tensile damage constitutive model of CA-UHPC is established considering the effect of coarse aggregate and steel fibers.
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