Effect of dry-wet cycles on mechanical properties of polyurethane porous mixture

Abstract

ABSTRACT Polyurethane porous mixture (PUPM) is a novel material with potential to extend the service life of pervious pavement. The porous structure makes the interior of the pavement material inevitably exposed to frequent cyclic action of environmental factors. However, the mechanical property decay behaviour of PUPM under the dry-wet cycles formed by water, air and corrosive ions is still unclear. Therefore, the mechanical properties of PUPM under different dry-wet cycles were characterised by Marshall stability, splitting strength and uniaxial compression strength tests. The variations in the microscopic properties of PUPM were investigated by computed tomography (CT), scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectroscopy. The grey entropy correlation theory was used to analyse the effect of variations in the functional groups of polyurethane on the mechanical properties of PUPM. It was concluded that the ageing of the polyurethane and the disruption of the bond at the binder-aggregate interface are the fundamental reasons for the mechanical property decay of PUPM. The influence of each functional group on the mechanical strength of the PUPM is in this descending order: amino groups linked to the carbonyl groups, carbonyl groups, ether bonds, methylene groups, and amino groups formed hydrogen bonds with water.