Preparation of Polyurethane Binders and Their Performance for Fast Pothole Patching

It is important to repair potholes timely and quickly for controlling the pavement deterioration and minimizing the adverse impacts to the traffic. In this contribution, a series of fast-curing two-component polyurethane (PU) binders with varying hard segment content (HSC) were prepared and used to prepare PU mixtures (PUMs) through mixing with aggregates. The influences of HSC on the chemical composition, mechanical and thermal properties, and water resistance of the PUs were investigated. The Marshall stability, splitting tensile strength, and raveling resistance of the compacted PUMs were also investigated. The results demonstrated that the prepared PUs had good mechanical properties and water resistance, and showed a tensile strength higher than 25.0 MPa and an equilibrium water uptake less than 0.6%. With increasing the HSC from 40% to 60% by weight, the tensile strength increased from 25.0 to 30.4 MPa, and the tensile strength retention increased from 64% to 88%. The compacted PUMs possessed high initial Marshall stability ($>3\mathrm{kN}$ after setting the specimen for 30 min) due to the fast curing of the PUs. The splitting tensile strength of the compacted PUMs with and without freeze–thaw cycles were, respectively, higher than 2.03 and 1.08 MPa, and increased with the increasing of HSC. The raveling resistance deteriorated with the increasing of HSC from 40% to 50% by weight and almost kept unchangeable with $\mathrm{HSC}\ge 50\%$ by weight. This deteriorating raveling resistance might be attributed to the increasing hardness of the PUs, which could lead to poor energy dissipation during the Cantabro test.