Evaluation of tensile failure behavior of ultra high performance concrete under double-edge wedge splitting and direct tension loadings

UHPC tensile strength is often measured indirectly through splitting tests and flexural tests substituted for direct tensile tests. However, the tensile strain-hardening and multiple cracking performance of UHPC is highly sensitive to the testing techniques and the specimen shape used. In this paper, the double-edge wedge splitting (DEWS) test and direct tensile test were performed to evaluate the tensile strain-hardening properties and damage evolution of UHPC. The digital image correlation (DIC) technique was utilized to detect the cracking opening displacement (COD) and evaluate the damage evolution in the tensile stress vs. crack opening response. The results show that the tensile strength between DEWS and direct tensile tests in UHPC strain-hardening and strain-softening stages had a high correlation value of 0.98. Moreover, the difference in cracking strengths in the DEWS and direct tensile tests was less than 5%, and those of peak strengths were fewer than 5.23 MPa. An improvement in relative COD increment was observed in DEWS and direct tensile tests before 90% of the peak load at the post-peak branch. Results indicate that the DEWS testing is an efficient way to evaluate the UHPC tensile failure properties.