Self-compacting polyurethane mixture for steel bridge pavement: characterisation and optimisation of constituent materials

Self-compacting polyurethane mixture (SPUM) is proposed as an innovative paving material for the steel bridge deck. In this study, polyurethane (PU) binder with different compositions and various types of coarse aggregate and fillers were characterised and optimised for formulation of SPUM. The results demonstrate that a mass ratio of 48%:52% between PU prepolymer and chain extender, as well as 1.5% of curing agent, is optimised for the synthesis of PU binder. The utilization of pebble coarse aggregate and slag filler contributes to larger slump and strength in polyurethane mixture and mortar. Based on grey correlation analysis, it is found that the primary influential factor is the axial coefficient of coarse aggregate for slump and strength of SPUM. Finally, the morphological characteristics of coarse aggregate yield more impact on the slump of SPUM than its strength. The research findings facilitate design and application of SPUM for steel bridge deck pavement.