Mechanical properties and freeze–thaw resistance of polyurethane-based polymer mortar with crumb rubber powder

In this study, it was considered that the effects of two polyurethane (PU) / sand ratios (25:100 and 35:100) and four crumb rubber powder contents (0 to 15%, 5% interval) on the flexural toughness, splitting strength and freeze–thaw resistance of polyurethane-based polymer mortar (PUM). Scanning electron microscopy (SEM) was used to analyze the microstructure of PUM. The results showed that adding crumb rubber powder improved the flexural toughness and freeze–thaw resistance of PUM. The flexural and splitting tensile strength of the two sets of PUM mixed with 5% crumb rubber powder were enhanced by 11.6% and 10.4%, 8.7% and 10.0%, respectively. Microscopic analysis showed that the internal foam pores and interfacial transition zone (ITZ) were responsible for the strength reduction in PUM. There was no peeling of specimens at corners and edges after 200 freeze- thaw cycles (FTCs), and the mass loss of PUM at different FTCs was negative. The recommended proportion of crumb rubber powder in PUM varies from 5% to 10% can serves as a pavement surface repair material.