Fundamental insights into the crack propagation behavior of functional gradient ultra-high-performance concrete using the digital image correlation method

Abstract

Here, the mechanical properties and crack propagation nalysing of functional gradient ultra-high-performance concrete (FGUHPC) were nalysin using the digital image correlation (DIC) method. The fiber layer thickness (0, 25, 50, 75, and 100 mm) was varied to evaluate the impact on the FGUHPC. A quadratic equation was introduced to evaluate the compressive strength of FGUHPC, and a numerical model based on nonlinear fracture mechanics was established to predict the load crack opening displacement (COD) relationship. Results indicated that the maximum contribution of fibers to flexural strength occurred with a fiber layer thickness of 75 mm. The strength enhancement factor (ξ) was 1.139 and the fracture factor (KIC) was 1.5. The crack propagation nalysing of FGUHPC displayed an increasing curvilinear trend as the fiber layer thickness increased. The mid-span vertical displacement and crack opening displacement had a linear relationship, and the scale factor was 0.549. The fiber layer thickness had a limited effect on the fiber dispersion coefficient (α) and the orientation distribution (ηθ). The two-parameter exponential function proposed accurately evaluated the probability of fiber distribution. The trilinear matrix softening accurately predicted the load-COD curves. Compared to a fiber layer thickness of 100 mm, the specimen with a thickness of 75 mm reduced cost by 13.3% while only decreasing strength by 4.4%, demonstrating the potential of FGUHPC for practical engineering applications.