Abstract:
To investigate the mechanism of the influence of different components on the mechanical performance of high-strength polyurethane composites (HSPUC) prepared with the addition of molecular sieve dosages, 16 groups of HSPUC with different isocyanate indices (
R), molecular sieve dosages, and polymer to cement ratios were designed. The compressive, flexural, and tensile strengths of each mix ratio of HSPUC were tested through macroscopic experiments. The influence of various factors on the strength and stress-strain curves was analyzed, and the optimal mix ratio of HSPUC was obtained. The intrinsic influence mechanism of various factors on the mechanical performance of HSPUC was revealed by combining FT-IR and SEM. The macroscopic experiments showed that with the increase of the
R value, the increase of molecular sieve content, and the decrease of the polymer to cement ratio, the compressive, flexural, and tensile strengths of HSPUC all showed a trend of first increasing and then decreasing, and the elasto-plastic characteristics of the stress-strain curves gradually weakened. When
R was 1.25, the molecular sieve dosage was 7.5%, and the polymer to cement ratio was 1.0, the compressive, flexural, and tensile strengths of HSPUC were 104.8 MPa, 79.4 MPa, and 25.1 MPa, respectively, and the tensile strain energy density was 0.085 J·mm
−3, showing the most superior strength and excellent toughness performance. Microscopic experiments indicated that the
R value determined the proportion of soft and hard segments in HSPUC; the addition of molecular sieves optimized the pore structure of HSPUC. Based on the measured stress-strain curves and the constitutive relationship of ordinary concrete, a constitutive model for HSPUC under tension and compression was established, providing a foundational model for the engineering application of HSPUC.