Dynamic mechanical properties and damage constitutive model of high-toughness recycled aggregate concrete under high strain rate impact loads

High-toughness recycled aggregate concrete (HTRAC) demonstrates significant advantages in the field of green building materials , but its performance deficiencies under impact loads limit its widespread application. In this study, plain recycled aggregate concrete (PRAC) and HTRAC specimens were prepared and tested using Split Hopkinson Pressure Bar (SHPB) tests to evaluate their mechanical performance at different strain rates . At a strain rate of 1 × 10 2 /s, the peak stress, peak strain, and ultimate strain of HTRAC increased by 0.87 times, 1.18 times, and 3.2 times, respectively. The proposed dynamic increase factor model accurately predicts the experimental results and a dynamic stress-strain equation considering strain rate effects was established. A novel modulus degradation factor model based on secant modulus was defined, exploring the evolution of damage variables with strain rate. A dynamic damage constitutive model based on the equivalent strain hypothesis was developed. This model provides theoretical support for the application of HTRAC in practical engineering. • Developed a rate-dependent factor model for constitutive characteristic parameters. • Provided the damage evolution law of HTRAC under various strain rates. • Proposed a dynamic damage constitutive model validated by experimental data.