Damage parameters and crack morphology in high strength concrete BBR9 under dynamic uniaxial compressive loading: An experimental study

In recent years, there has been significant growth in the use of high-strength concrete (HSC) in structures designed to withstand extreme events such as collisions, terrorist attacks, and earthquakes. Continuum damage mechanics has been utilized to develop constitutive models that can capture the damage evolution in concrete materials under such conditions. These models must be validated against experimental data obtained under controlled laboratory conditions. Yet, no experimental dataset currently exists that accurately quantifies the damage evolution and its influence on the residual mechanical properties of HSC. The present study aimed at investigating the damage initiation, progression, and morphology of HSC-Baseline Basic Research Mixture 9 (BBR9) when subjected to dynamic uniaxial compressive loading. A Kolsky compression bar system was implemented to introduce distinct damage states in the HSC-BBR9 specimens. Thereafter, the partially damaged specimens were tested to quantify their residual mechanical properties. Accordingly, stiffness-based and strength-based constitutive damage parameters were adopted to propose an indirect quantification of the damage state based on the deterioration of mechanical properties. In addition, the X-ray micro‐computed tomography (micro-CT) technique was utilized to extract measurements of 3D crack networks (e.g., crack volume and surface area) that provide a direct quantification of the damage state based on microstructural evidence. The results demonstrated that the HSC-BBR9 material can maintain its residual mechanical properties into the post-peak regime. In the initial stages of damage, stiffness and strength deteriorate at a proportional rate; however, as damage accumulates, the rate of stiffness degradation increases. Moreover, correlations between constitutive damage parameters and 3D crack measurements were established. • The concrete damage models do not accurately capture the deterioration in its mechanical properties under dynamic loading. • Kolsky compression bar and X-ray micro-CT are used to correlate constitutive damage parameters and crack measurements. • The progression of damage in the HSC-BBR9 material extends to the post-peak deformation. • The impact of damage-induced crack network on the residual mechanical properties is strongly dependent on strain rate.