Introduction
Professor XU Jian, Principal Investigator of NEXCEL 2024 TDA project "Development and demonstration of high-performance polymer mixture pavement with higher durability and longer service life" from Research Institute of Highway Ministry of Transport，has published a paper entitled "Degradation mechanism and performance of polyurethane mixture under water conditions" in "Construction and Building Materials" (SCI) recently.
Abstract：
Polyurethane mixtures exhibit improved mechanical properties and low-carbon construction characteristics, which make them gradually popularized and applied in pavement. However, their high water sensitivity is a major shortcoming in road performance. In this study, the evolution patterns of polyurethane mixture properties were first investigated under water conditions. Furthermore, the variation characteristics of the polyurethaneaggregate interface strength were explored under immersion conditions. Simultaneously, the deterioration mechanisms of polyurethane binder were analyzed through microscopic morphology, chemical structure and hydrogen bonding degree. The experimental results show that the water’s erosive effect induces rapid interfacial strength loss (52.5 %-68.8 %) and key mechanical properties degradation (37.2 %-48.4 %) in polyurethane mixture during the initial 4 days of immersion. Prolonged inundation (4–16d) comparatively mitigates these effects, with interfacial strength reduction decreasing by 33.6 %-38.4 % and key mechanical properties decline slowing by 19.9 %-34.9 %. This two phases deterioration pattern (rapid decline in the early stage and moderate decline in the later stage) was observed at all three temperatures (-18℃,25℃ and 60℃), and the high temperature (60℃) exhibited the most pronounced deterioration effect. Further analyses revealed that degradation of the polyurethane binder’s surface hydrophobicity directly weakens the interfacial adhesion effect with aggregates. Furthermore, the high temperature promotes the simultaneously occupation of hydrogen-bonding sites in soft-hard and hard-hard segments by water molecules, increasing the proportion of disordered hydrogen bonding from 29.0 % to 47.5 %. This process exacerbates water-induced microphase separation and reduces crosslinking density in the polyurethane binder, ultimately leading to multi-pathway deterioration of the poly urethane mixture’s water stability.
Paper Details:
Construction and Building Materials 490 (2025) 142467