Polyurethane-based composite binder for poroelastic road surface: composition, preparation and properties

Abstract

To address the high cost and poor water stability of polyurethane (PU) binder used in poroelastic road surface (PERS), a type of PU-based composite binder prepared at room temperature was proposed by using PU as the main ingredient, emulsified asphalt (EA), cement, and defoamer as auxiliary agents. The stabilities of different types of polyurethane-emulsified asphalt (PU-EA) blend systems were investigated and the mix composition of the PU-EA blend system was determined through molecular dynamics (MD) simulations. The interaction mechanisms of all components of the PU-based composite binder were revealed by microscopic measurements through Fourier transform infrared (FTIR) spectroscopy and fluorescence microscopy (FM). The strength and water stability of the PERS mixture bound by the PU-based composite binder were evaluated by the indirect tension (IDT) test and the Cantabro abrasion test. The results showed that the stability of the polyether polyurethane (PEUR)-cationic emulsified asphalt (CEA) blend system was the best, and the potential energy of the PU-EA blend system was the lowest when the PU content was around 50 wt%. Both physical and chemical reactions occurred simultaneously in the polyurethane-emulsified asphalt-cement (PU-EA-C) blend system's components. The calcium silicate hydrate (C-S-H) enhanced the crosslinking gel properties of the PU-EA-C blend system. Cement improved the performance of the PERS mixture in a more efficient way than the PU. When the PU-based composite binder composed of 50 wt% PU, 41 wt% EA, 9 wt% cement, and 0.5 wt% defoamer was used, the water stability and strength performance of PERS mixture were the best. The material cost of the suggested PU-based composite binder was nearly half that of commonly used PU, while the material cost of the PERS mixture was reduced by 25%. These findings would serve as useful references for the promotion and application of PERS pavement.