Research on the Properties of a New Type of Polyurethane Concrete for Steel Bridge Deck in Seasonally Frozen Areas

To widen the application scenarios of polyurethane concrete materials, a new type of polyurethane concrete material for steel bridge deck pavement in seasonally frozen areas was developed, and it was applied to the deck pavement engineering of steel bridges with orthotropic slabs. In this paper, we studied the properties of new polyurethane concrete through the tests of compressive strength, flexural tensile strength, and bond strength with steel plates of polyurethane concrete at different temperatures from −40 °C to 60 °C, totaling 11 temperature levels. We analyzed the elastic modulus, peak strain, and stress–strain relationship curve at the standard temperature. Then, we also conducted SEM test and IR test for the internal destruction form of polyurethane concrete, and analyzed the mechanism of its strength formation. The results show that with increasing temperature, the linear elastic range of polyurethane concrete material is shortened, the elastic modulus, compressive strength, and flexural tensile strength of the material all show a downward trend, and the peak strain and ultimate strain increase significantly. The failure state of the material is gradually transformed from brittle fracture at low temperature to plastic failure at high temperature, and the ductility of the material is significantly improved. Comparing with ones at the standard temperature, the compressive strength at 60 °C is 49.62 MPa downward by 45% and the bending tensile strength of the prism test at 60 °C is 12.34 MPa downward by 51%. Although the stress performance decreases significantly with the change of temperature, it can still meet the strength requirements of the bridge deck pavement for the pavement material. At present, the relevant research is mainly focused on the mechanical properties of new concrete under the influence of high temperature, but research on the mechanical properties of new concrete along with the temperature change is relatively limited. The proposed flexural–tensile constitutive model of polyurethane concrete for steel bridge deck pavement in seasonal freezing areas under the influence of temperature is in good agreement with the experimental results, which can provide a theoretical basis for the application of polyurethane concrete in engineering.