Investigation on the Tensile Fracture Properties of Fully-Graded Concrete Considering Aggregate Morphological Characteristics via Peridynamics

Fully graded concrete exhibits significantly enhanced mechanical properties due to optimized aggregate gradation. However, the effects of coarse aggregate morphological characteristics at the microscale-such as axial ratio (Ar) and angularity coefficient (Ac)-on fracture behavior remain insufficiently understood and require further investigation. This study investigates the fracture behavior of fully graded concrete using a peridynamic approach. First, a multilinear constitutive model of concrete considering nonlocal effects and damage evolution is constructed. Second, aggregate modeling via the Tensile-Concave Synthesis Method in peridynamics, and different property bonds and random bond parameters are introduced to characterize the heterogeneity and initial defects of concrete. Finally, the effects of loading rate, aggregate randomness, and the parameters Ar and Ac on the uniaxial tensile properties of concrete are systematically studied. The results demonstrate that peridynamics accurately captures the entire process of crack initiation and propagation in fully graded concrete. Uniaxial tensile behavior exhibits strong rate dependence. Different random aggregate models result in variations in the peak tensile strength of concrete. With the increase in Ar, the peak tensile stress gradually decreased by 4.15%, whereas the elastic modulus increased by 14.31%. As Ac increased, the peak stress exhibited an overall trend of first increasing by 5.14%, followed by a decrease of 3.8%. Therefore, in numerical simulations, the influences of loading rate and aggregate randomness should not be overlooked. Moreover, to enhance the strength of fully graded concrete, the proportion of aggregates with large Ar and Ac values should be minimized.