Laboratory Investigations into Degradation Mechanism of Polyurethane Concrete Properties under Various Immersion Conditions

ABSTRACT Polyurethane concrete (PC) is a novel cold-mixed, cold-paved, and environmentally friendly road construction material. This study undertook a comprehensive analysis of the deteriorating mechanism impacting the water stability of PC under various water immersion conditions based on the employment of indoor testing, microanalysis, and statistical methods. Initially, the influence of void ratio, temperature, and immersion duration were assessed and quantified on the PC’s water stability through damage performance tests executed under both continuous and intermittent immersion scenarios. Subsequently, a nonlinear fitting method was used to establish a prediction model for the PC performance decay under continuous water immersion. Furthermore, microscopic insights into the causes of PC performance deterioration were revealed through scanning electron microscope and Fourier transform infrared spectroscopy tests. The experimental findings demonstrated that the PC performance experiences deterioration and tended to be stabilized under continuous immersion conditions. Moreover, the overall trend of PC performance degradation under intermittent immersion aligned with this pattern, with the final stabilization value being similar; a certain degree of performance recovery was observed under un-immersed conditions. In terms of factors influencing water stability, immersion time was greater than immersion temperature and void ratio, wherein the latter two impacted the rate of performance decay but not the ultimate stability value. The primary reason for the PC performance decay was identified as the hydrolysis reaction between the urethane group and water, wherein the resulting alcohol was reacted with the carbon chain, leading to a reduction in the hydrolytic stability of polyurethane.