# Study on Mechanical Properties of Modified Polyurethane Concrete at Different Temperatures
## 5 Conclusions  
In this research, the cube compressive test, splitting tensile test and uniaxial compression test of modified polyurethane concrete specimens were performed at different temperatures. The failure mode, cube compressive strength, splitting tensile strength, axial compressive strength, elastic modulus and the compressive stress-strain curves of the modified polyurethane concrete were obtained. The influence of temperature on the mechanical properties of modified polyurethane concrete was analyzed. A uniaxial compression constitutive model considering the temperature effect was established. Based on the research results, the following conclusions can be drawn:  
(1) The failure mode of modified polyurethane concrete is significantly affected by temperature. In the cube compressive test and uniaxial compression test, specimens are brittle failure at low temperature and plastic failure at high temperature. With the temperature increasing, the maximum crack width of the specimen at failure decreases, the crack propagation speed is slower and the integrity of the specimens are better after failure. In the splitting tensile test, the main cracks are straight lines at low temperatures and curves at high temperatures.  
(2) The temperature has a significant effect on the mechanical properties of modified polyurethane concrete. With the increase of temperature, the cubic compressive strength, split tensile strength, axial compressive strength and elastic modulus decrease, and the peak strain increases. The temperature has a slight impact on the ratio of splitting tensile strength to cubic compressive strength. The ratios of axial compressive strengths to cube compressive strengths are quite different at different temperatures.  
(3) A constitutive model of modified polyurethane concrete under uniaxial compression considering the influence of temperature was established, and reasonable agreement was found to exist between the constitutive model calculation results and the experimental results. The experimental results provide material parameters for the finite element analy  
Figure 21: Comparison of constitutive model with experimental results.  
sis of modified polyurethane concrete bridge deck pavement. The proposed constitutive model can accurately describe the mechanical properties of modified polyurethane concrete at different temperatures, which can provide a theoretical basis for the structural design and numerical analysis of modified polyurethane concrete. Meanwhile, it provides a test basis for the influence of the coupling effect of temperature and load on the modified polyurethane concrete bridge deck pavement.  
Conceptualization, X.H.; methodology, J.L., F.F. and W.W.; validation, F.F. and W.W.; formal analysis, F.F.; writing--original draft preparation, J.L.; writing--review and editing, J.L. and W.W.; supervision, X.H.; project administration, F.F. and S.X.; funding acquisition, X.H. All authors have read and agreed to the published version of the manuscript.  
This research is substantially funded by the National Natural Science Foundation of China (No. 51925808) and the Science and Technology Research and Development Plan of China Railway Development and Investment Group Co., Ltd. (No. 2021-Category B-04).  
Not applicable.  
The authors declare no conflict of interest.