| Corrosion of steel bars in concrete structures is the main reason that affects the service life of structures.Since the emergence of epoxy resin coated steel bars,it has been widely used because of its effectiveness,economy and fast construction.However,the problems of brittle cracking and aging of traditional epoxy coatings have not been completely solved,which is easy to be damaged during production,transportation and application,resulting in the loss of protective effect of coatings.Therefore,it is of great significance to develop green waterborne epoxy resin and epoxy coated steel bar with high toughness.The main contents and achievements of this paper are as follows: 1.The green polyurethane toughened water-based epoxy emulsion was synthesized synchronously.Through the study on the particle size,stability,mechanical properties and corrosion resistance of lotion,the synthetic scheme of waterborne epoxy resin lotion was obtained.Effectively reduce the content of organic solvents,improve the toughness and corrosion resistance of water-based epoxy resin.2.The epoxy coating film was made by crosslinking the prepared water-based epoxy resin emulsion with the self-made curing agent made in the laboratory.The effects of inorganic fillers and nanoparticles on the durability of waterborne epoxy coatings were studied,and their mechanical properties,corrosion resistance,wear resistance,aging resistance,and other properties were tested for validation.The results showed that the addition of inorganic fillers and nanomaterials significantly improved the mechanical properties and corrosion resistance of the coating.The coating impregnated in 3.5% sodium chloride solution for 60 days has a corrosion current density of 0.004 μA/cm2,and has no foaming,rusting,peeling,cracking and other phenomena.The coating mass loss is 20 mg after 1000 cycles of CS-10 wheel under 1 kg load.Coating hardness 2 H,impact resistance 100 cm,bending resistance 2 mm,adhesion level 0.3.Apply coating to steel bars,design and study the coating process and preparation process of coated steel bars,and test whether the coated steel bars meet the application requirements through the thickness of the steel bar coating,the continuity of the steel bar coating,and the resistance to chloride penetration.4.The mechanical properties of coated steel bars were studied through cold bending tests.No visible cracking or peeling was observed after 180° cold bending test.The deformation coordination ability of coated steel bar was studied through contact strain gauge measurement and non-contact speckle test.It was proved that the steel bar and coating strain began to appear inconsistent when the strain was 24000 με,and the longitudinal deformation(Eyy)at the crack of the coating was 10.3469 mm,indicating that the mechanical properties and deformation coordination of coated steel bar were good.The fracture mechanism of the steel bar coating is further studied and analyzed by the micromorphology test,which provides support for the industrial application of waterborne epoxy coated steel bar. |
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