Enhancing the toughness and low-temperature performance of epoxy asphalt via PTMG-MDI modified epoxy resin

Epoxy asphalt is widely applied in steel bridge deck paving due to its high strength and thermal stability. However, the thermosetting epoxy resin becomes highly brittle after curing, resulting in insufficient toughness and poor low-temperature crack resistance. To address this issue, a novel high-toughness epoxy asphalt (HTEA) was developed by grafting polytetramethylene ether glycol-diphenylmethane diisocyanate (PTMG-MDI), serving as polyurethane flexible segments, onto epoxy resin and incorporating it into asphalt. The cured high-toughness epoxy resin (HTER) exhibited good thermal stability and mechanical properties, with a tensile strength of 4.05 MPa and an elongation at break of 143 %. HTEA showed slightly reduced tensile strength but significantly increased elongation at break. Rheological tests indicated that the retention time of HTEA reached up to 37 min. The storage modulus decreased in the low-temperature region, while the high-temperature creep compliance changes only slightly, indicating improved creep recovery performance. The fracture morphologies of HTER and HTEA exhibits ductile characteristics. The PTMG-MDI increases the density of cross-linking points in the three-dimensional network, thereby improving the low-temperature crack resistance of epoxy asphalt. When the HTER content is 40 % the glass transition temperature of HTEA is as low as −28.7℃, and the testing temperature is −24℃, the maximum creep modulus reaches 492 MPa, with a minimum creep rate of 0.242, indicating excellent low-temperature performance.