Preparation and Properties of Epoxy Asphalt Modified by Biomimetic Graphene Oxide Nanocomposites

In order to solve the current problem of insufficient toughness of epoxy asphalt and immiscibility between resin and asphalt binder (not aged) in epoxy asphalt, nanomodifiers (${\mathrm{GOs}\text{-}\mathrm{CS}\text{-}\mathrm{Ca}}^{2+}$) were prepared by a biomimetic mechanism from chitosan (CS), calcium ions (${\mathrm{Ca}}^{2+}$), and graphene oxide nanoplatelets (GOs). In ${\mathrm{GOs}\text{-}\mathrm{CS}\text{-}\mathrm{Ca}}^{2+}$, CS connects GOs through calcium ion coordination bonds and amide bonds. ${\mathrm{GOs}\text{-}\mathrm{CS}\text{-}\mathrm{Ca}}^{2+}\text{-}\text{modified}$ epoxy asphalt was prepared by directly adding different percentages of ${\mathrm{GOs}\text{-}\mathrm{CS}\text{-}\mathrm{Ca}}^{2+}$ to epoxy asphalt. Then, the properties of ${\mathrm{GOs}\text{-}\mathrm{CS}\text{-}\mathrm{Ca}}^{2+}\text{-}\text{modified}$ epoxy asphalt were analyzed through macro and micro tests. The macroscopic tests included tensile, cyclic, and stress relaxation tests. The microscopic tests included fluorescence microscopy (FM) and scanning electron microscopy (SEM) tests. Tensile tests showed that after adding 0.05% ${\mathrm{GOs}\text{-}\mathrm{CS}\text{-}\mathrm{Ca}}^{2+}$ to the total mass of epoxy asphalt, the tensile strength and fracture toughness of epoxy asphalt increased by 29.6% and 20%. Cyclic tensile tests showed that ${\mathrm{GOs}\text{-}\mathrm{CS}\text{-}\mathrm{Ca}}^{2+}\text{-}\text{modified}$ epoxy asphalt had greater consuming work recovery capacity, and stress relaxation tests showed that the addition of ${\mathrm{GOs}\text{-}\mathrm{CS}\text{-}\mathrm{Ca}}^{2+}$ delayed the relaxation modulus decline of epoxy asphalt. The infrared spectrum, scanning electron microscope, X-ray diffraction, and Raman spectra of ${\mathrm{GOs}\text{-}\mathrm{CS}\text{-}\mathrm{Ca}}^{2+}$ in the micro test can show the successful synthesis of ${\mathrm{GOs}\text{-}\mathrm{CS}\text{-}\mathrm{Ca}}^{2+}$. FM and SEM of ${\mathrm{GOs}\text{-}\mathrm{CS}\text{-}\mathrm{Ca}}^{2+}\text{-}\text{modified}$ epoxy asphalt showed that the addition of ${\mathrm{GOs}\text{-}\mathrm{CS}\text{-}\mathrm{Ca}}^{2+}$ could reduce the particle-size distribution of the asphalt phase in epoxy resin and establish a miscible bridge between epoxy resin and asphalt, which led to the improvement of macroscopic mechanical properties of ${\mathrm{GOs}\text{-}\mathrm{CS}\text{-}\mathrm{Ca}}^{2+}\text{-}\text{modified}$ epoxy asphalt. Finally, the modification mechanism of ${\mathrm{GOs}\text{-}\mathrm{CS}\text{-}\mathrm{Ca}}^{2+}\text{-}\text{modified}$ epoxy asphalt was proposed by combining macroscopic and microscopic test results.