Dynamic Mechanical Properties and Constitutive Model of Early Strength Concrete at Different Age

Abstract

Early strength concrete is widely used in rapid repair and special working conditions. And it is of great significance to study its early dynamic mechanical properties for normal use and safety evaluation. The Ф100 mm SHPB test system is used to study the dynamic mechanical properties of early strength concrete at ages of 4 h, 12 h, 1 d, 3 d, 7 d and 28 d, and the Dynamic Increase Factor (DIF) model of early strength concrete at different ages is established. In addition, based on Ottosen constitutive model, the dynamic constitutive model of early strength concrete considering strain rate and age is established. The results show that the mechanical indexes of early strength concrete have strain rate strengthening effect and age strengthening effect. The dynamic compressive strength and specific energy absorption of early strength concrete increase with the increase of strain rate or age. With the increase of age, the strain rate sensitivity of mechanical indexes of early strength concrete increases. After comparing the calculation formulae of DIF given by CEB, Tedesco, etc., the DIF model of early strength concrete at different ages is proposed. The dynamic constitutive model curves show good agreement with the test curves, which can accurately describe the stress-strain relationship of early strength concrete before failure at different ages.