Research on splitting damage characteristics of concrete after different thermal cycles

Effects of thermal cycles on the mechanical properties and damage characteristics of concrete under splitting tests were investigated by using digital image correlation (DIC) and acoustic emission (AE) techniques. The quantitative investigation was conducted on damage changes in concrete after thermal cycles. A damage constitutive model based on AE parameters was established. Results show that an appropriate increase in thermal cycles strengthened the tensile strength and tensile modulus of concrete, but the strength decreased and the deformation increased with continuously increased thermal cycles. As thermal cycles increased, ringing counts became more numerous and intensive, accompanied by a greater concentration of damage inside concrete. Concrete specimens underwent the failure evolution process of tensile failure predominantly → mixed failure → shear failure predominantly by analyzing RA (rise time/amplitude)-AF (average frequency) characteristic parameters and macroscopic fracture characteristics. More thermal cycles accelerated the formation of the non-uniform principal strain field and local strain concentration zone on the concrete surface during the loading process. Besides, a continuum damage model using the AE ringing count as a variable was proposed in this paper, which was able to describe the evolution characteristics of various mechanical parameters of concrete treated with different thermal cycles during the deformation and failure process. • AE and DIC were employed to study the damage characteristics of concrete subjected to thermal cycles. • The effects of thermal cycles on the mechanical properties and failure modes of concrete were analyzed. • Increased thermal cycles led to a transition in concrete behavior from brittle to ductile, with an increase in peak strain. • A damage constitutive model based on AE parameters was proposed, accurately fitting experimental results and describing the tensile behavior of concrete under thermal cycles.