In order to solve issues related to bridge girders, expansion devices and road surfaces, as well as other structures that are prone to fatigue failure, a kind of fatigue-resistant elastic polyurethane concrete (EPUC) was obtained by adding waste rubber particles (40 mesh with 10% fine aggregate volume replacement rate) to conventional engineering polyurethane concrete (PUC). Based on the preparation and properties of EPUC, its constitutive relation was proposed through compression and tensile tests; then, a scanning electron microscope (SEM), an atomic force microscope (AFM) and a 3D non-contact surface profilometer were used to study the failure morphology and micromechanisms of EPUC. On this basis, four-point bending fatigue tests of EPUC were carried out at different temperature levels (−20 °C, 0 °C, 20 °C) and different strain levels (400 με~1200 με). These were used to analyze the stiffness modulus, hysteresis angle and dissipated energy of EPUC, and our results outline the fatigue life prediction models of EPUC at different temperatures. The results show that the addition of rubber particles fills the interior of EPUC with tiny elastic structures and effectively optimizes the interface bonding between aggregate and polyurethane. In addition, EPUC has good mechanical properties and excellent fatigue resistance; the fatigue life of EPUC at a room temperature of 600 με can grow by more than two million times, and it also has a longer service life and reduced disease frequency, as well as fewer maintenance requirements. This paper will provide a theoretical and design basis for the fatigue resistance design and engineering application of building materials. Meanwhile, the new EPUC material has broad application potential in terms of roads, bridges and green buildings.
To solve the problem that the repair material of the bridge's expansion joint anchorage area is prone to debonding from the other bridge components, polyurethane concrete was designed and prepared, and the bonding performance of polyurethane concrete was tested by the bond splitting test, bond direct shear test, bond oblique shear test, and steel reinforcement pull-out test. The results show that the interfacial bond strength of polyurethane concrete and cement concrete can be improved by increasing the interfacial roughness. The bond splitting strength increases by up to 91.4%, the bond direct shear strength increases by up to 55.2%, and the bond oblique shear strength increases by up to 28.9%. The bond strength between polyurethane concrete and cement concrete are minimally influenced by temperature. An increase in the diameter of the reinforcement or the length of the bonded anchorage can increase the ultimate pull-out strength of the polyurethane concrete and the steel reinforcement. Polyurethane concrete is a novel composite material with excellent bonding performance with cement concrete and steel reinforcement, which can be widely used in practical projects, such as repairing bridge expansion joint anchorage areas in the future.
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