Study on Performance of UHPC with Curvilinear Steel Fibers

Abstract

AbstractThis study investigates the effect of the degree of bending and doping of steel fibers on the macroscopic mechanical properties of UHPC. To achieve this, four curvilinear steel fibers of different curvature radius (20, 30, 40 and 50 mm) and straight steel fiber were employed. Mechanical properties of UHPC including flowability, compressive and flexural strengths were assessed. Moreover, analysis of flexural tests on curvilinear fiber UHPC specimens was performed using finite element simulation. The test results show that the use of curved steel fibers reduces the flowability of the matrix compared to straight fibers in the UHPC matrix, and flowability of UHPC decreased significantly with increase of fiber bending. The results of the compressive and flexural tests showed that the compressive and flexural strengths of the specimens were significantly improved with the increase of fiber doping compared with the matrix without fiber doping. In terms of compressive strength, the curvilinear steel fibers can further increase the compressive strength of UHPC by 5–8 MPa compared with the straight steel fibers. In terms of flexural strength, the flexural strength of the specimens doped with straight fibers was higher than that of the curvilinear fiber specimens when the fiber dosing was less than 1% by volume due to the poor dispersion of curvilinear fibers. However, the average bonding strength of curved fibers was higher than that of straight fibers, and the flexural strength of curved fiber specimens was better than that of straight fiber specimens when the fiber dosing was 1.5 and 2.0%.KeywordsCurvilinear steel fibersUHPCFlexural strengthTensile performance