Direct Tensile Properties and Stress–Strain Model of UHP-ECC

This research developed an ultra-high-performance engineered cementitious composite (UHP-ECC), which combines the properties of strain-hardening, multiple cracking, and high mechanical strength. The compressive strength of the UHP-ECC reached 150 MPa at 28 days under standard curing conditions, whereas the tensile strength and strain capacity of the UHP-ECC were 18 MPa and 8%, respectively. Different fiber volumetric ratios and geometries (fiber length and diameter) were used to investigate the influences of fiber-reinforcement parameters on the mechanical and crack-pattern properties of UHP-ECC, including the tensile strength, strain capacity, strain energy, crack number, and crack spacing. It was found that the fiber reinforcement parameters significantly influence both the mechanical properties and crack-patterns of UHP-ECC. Based on the test results, a bilinear tensile stress–strain model was proposed for UHP-ECC and its accuracy was demonstrated through comparisons with the test results.