Study on the Road Performance and Development Mechanism of Polyurethane Binder in Different Media Solutions

Abstract

Polyurethane pavements are often adversely affected by the natural water environment, and the factors such as acid rain, road alkalization, car engine oil and melt-icing salt will complicate the water environment of the pavement. To investigate the effect of acid rain, road alkalization, oil, salt and precipitation on the performance of polyurethane pavement, the changes of surface morphology, mechanical properties, temperature stability and other performance of polyurethane binders treated with different medium solutions were analyzed by solution soaking, mechanical tensile, thermogravimetry and other tests. The degradation mechanisms of polyurethane binder properties under different medium solutions were studied from the perspectives of microstructure, hydrogen bonding, and crosslinking density. The comprehensive evaluation of polyurethane usage in the road environment was based on the composite suitability index indicated by radar chart. The results showed that: (1) After treatment with acid, alkali, oil, salt, and water solutions, the toughness of the polyurethane binder is reduced, and apparent color changed are observed due to alterations in the surface chemical composition structure. (2) The degree of weakening of polyurethane binder properties by water, alkali, oil, acid, and salt increased in sequence. (3) The water solution has been proven to reduce the polyurethane binder’s macroscopic properties by weakening hydrogen bonds and cross-linking density. In contrast, the acidic and alkaline solutions have been demonstrated to accelerate the hydrolysis process of the polyurethane binder. (4) The destruction of the chemical bond of polyurethane by chloride ions was the underlying cause for the accelerated deterioration of polyurethane binder properties in salt solution. The degradation of polyurethane performance was primarily due to the swelling effect of the oil solution. The research findings hold significant implications for assessing the environmental adaptability of polyurethane pavements.

Keywords: Polyurethane binder, Pavement erosion environments, Road performance, Crosslink density, Hydrogen bond