Effect of temperature gradients on the microstructural characteristics and mechanical properties of concrete

Concrete is susceptible to cracking and damage when exposed to severe or repeated temperature gradients, leading to the deterioration of mechanical and durability properties, significantly impacting the normal operation and service life of structures. This study investigates the influence of temperature gradients on the deterioration of mechanical properties and microstructure in concrete. Experiments were designed to establish temperature gradients and detect the microstructure characteristics and mechanical properties post-damage. The microscopic mechanisms governing the evolution of mechanical properties under temperature differences were explored, and a mathematical relationship between them was analyzed. The findings reveal that the severity of thermal damage is directly proportional to the enhancement of temperature differences and proximity to the heat source. The temperature gradient-induced stiffness enhancement and structural damage contribute to a substantial reduction in split tensile strength, while compressive strength initially increases and then weakens. The peak displacement demonstrated a strong exponential relationship with the carbonation parameters. A mathematical model for the strength of concrete influenced by temperature gradients was established, considering the impacts of porosity and carbonation parameters.