Mechanical properties and constitutive model of waterborne polyurethane modified concrete in compression at different temperature

The surface cracking is one of the main causes for the deterioration of concrete structures exposed to large temperature variations in plateau, and a tough concrete is of critical importance for the service life of concrete structures. In this paper, a waterborne polyurethane modified concrete (WPMC) was prepared, and the compressive strength of WPMC at temperatures ranging from 20 degrees C to 80 degrees C was investigated. Digital image correlation (DIC) technology was employed to elucidate the evolution of compressive deformation in WPMC across various temperatures. Furthermore, Scanning Electron Microscopy (SEM) and Mercury Intrusion Porosimetry (MIP) were employed to reveal the mechanism behind the enhancement of WPMC's toughness. The results indicate that WPMC maintains good mechanical properties within the temperature range of 20 degrees C-80 degrees C. Compared to the controlled group of concrete, WPMC exhibits an increase in ultimate compressive strain by 16.67 %-109.09 %, an enhancement in energy absorption capacity by 30.45 %-118.61 %, and an augmentation in full-field lateral ultimate strain by 20.0 %- 48.0 %. A constitutive model for WPMC that considers the influence of temperature is proposed, providing an accurate assessment method for the stress-strain relationship of WPMC under compressive loading.