Uniaxial tensile test of high-strength high-ductility concrete (HSHDC): Mechanical response and toughness evaluation

To investigate the tensile strength of high-strength high-ductility concrete (HSHDC) with different fiber characteristic parameters and matrix types, thirteen groups of HSHDC thin plates were designed for uniaxial tensile tests. The effects of fiber type (polyethylene (PE) fiber and polyvinyl alcohol (PVA) fiber), PE fiber content (1.5%, 2.0%, and 2.5%), PE fiber diameter (22μm, 30μm, 35μm, and 40μm), water-binder ratio (w/b) (0.14, 0.16, and 0.18), and fly ash content (15%, 20%, and 25%) on the stress-strain curve, tensile strength, and strain of HSHDC were studied. Based on the uniaxial tensile tests, a tensile toughness evaluation method suitable for HDC characteristics was proposed. The results showed that the developed HSHDC material had a tensile strain exceeding 6%, a pre-peak strain energy density exceeding 360 kJ/m3, and an elastic modulus of approximately 40GPa. Fiber type, fiber diameter, w/b, and fiber content significantly influenced the strain-hardening response, tensile strength, and strain of HSHDC. In the cracking bridging process, the higher the proportion of fiber pull-out, the higher the tensile strain and ductility development coefficient of HSHDC. The proposed tensile toughness evaluation method can effectively evaluate the tensile toughness of HSHDC thin plates during its whole loading process, and it is suitable for comparing the tensile toughness of HSHDC with different fiber types and mix proportions.