High-Performance Cementitious Composites with Tensile Strain Capacity Up to 18%

At present, the ductility of engineered cementitious composites (ECC) is not sufficient to achieve compatibility with steel, which limits the application of ECC in composite structures. To prepare ECC with ultra-high tensile strain, tensile tests on eighteen types of ECC with different mix ratios were carried out. The effect of cementitious material composition, sand/binder ratio, and fiber hybridization on tensile properties was analyzed. Meanwhile, three types of ECC were developed and defined as ultra-high tensile property cementitious composites (UHTCC). UHTCC exhibits the characteristic of oversaturated cracking and obvious strain hardening during the tensile process. The tensile strain of UHTCC was up to 18.3% with an average tensile strength of 9.9 MPa. Meanwhile, UHTCC shows ultra-high flexural toughness and high compressive strength. In addition, the hybridization of PE fibers and macro-PP fibers has been proved to be beneficial to improve tensile strain capacity, with the cost of fibers decreased by 24.3%. To explore the causes of UHTCC’s ultra-high tensile strain, the state of the matrix and fibers after the tensile test was observed by scanning electron microscope. In addition, the cracking process of UHTCC was analyzed by comparing average crack spacing with the theoretical value. Further, a four-stage tensile constitutive model was proposed. And the new constitutive model has been verified to be applicable to three different types of UHTCC.