Study On Seawater Corrosion Resistance Of Geopolymer

With the economic development of the Yangtze River Delta,Pearl River Delta,and Bohai Bay region,coastal infrastructure had been built.Concrete exposed in the highly corrosive offshore environment was easily corroded and the repair cost was extremely high.In this paper,epoxy resin was used as a toughening agent to prepare metakaolin-based geopolymer composite materials mixed with epoxy resin.The macroscopic properties and seawater corrosion resistance of geopolymers with different epoxy resin dosages were studied.X-ray diffraction(XRD),scanning electron microscopy(SEM),fourier infrared spectroscopy(FTIR),energy spectrum analysis(EDS)and electrochemical workstation to analyze the raw material composition,micro-morphology,structural activity and resistance to chloride ion penetration.The main research results were as follows:(1)Epoxy resin lowers the p H value of the alkaline excitation solution,resulting in a low compressive strength of the metakaolin-based geopolymer mixed with epoxy resin in the early stage of curing.After 28 days of curing,the polycondensation reaction of the geopolymer was basically completed.The metakaolin-based geopolymer with 30wt% epoxy resin(EGP30)and the metakaolin-based geopolymer without epoxy resin(EGP0)differ in compressive strength by only 4.17 MPa.The flexural test results showed that the flexural strength of the geopolymer doped with epoxy resin was significantly enhanced,and the flexural strength of EGP30 was 1.54 times that of EGP0.(2)After blending with epoxy resin,the shrinkage properties of metakaolin-based geopolymers were significantly improved.The shrinkage rate of EGP30 was reduced by0.028% compared with that of EGP0.The results of SEM and nitrogen adsorbent studies showed that epoxy resin can significantly improve the pore size of geopolymers,effectively increase the density of geopolymers,and reduce the generation of micro-cracks;EDS experiments found that epoxy resins can change the geopolymer condensation The chain structure of the glue,with the increase of the amount of epoxy resin,the PSDS type long chain structure in the resin geopolymer increases;XRD / FTIR research results showed that the incorporation of epoxy resin hinders the process of polycondensation reaction,resulting in the geopolymerization of epoxy resin The mechanical properties of the objects in the early stage of maintenance were poor.(3)The results of seawater corrosion resistance experiments showed that after 56 days of seawater corrosion,the compressive strength of metakaolin-based geopolymers doped with epoxy resin increases,proving that seawater resistance of metakaolin-based geopolymers doped with epoxy resin The corrosion ability was higher,and the higher the epoxy resin content,the better the seawater corrosion resistance.Dry-wet cycle test results show that the resistance of epoxy resin geopolymers to dry shrinkage was positively correlated with the amount of epoxy resin and curing time.The microscopic experiment of the test piece after seawater corrosion proves that the seawater has not reacted chemically with the epoxy-based metakaolin-based geopolymer,and the microstructure was complete after 56 days of immersion.(4)Using an electrochemical workstation to conduct a chloride ion penetration experiment on cement mortar specimens with different coatings,a comparative analysis of uncoated,epoxy resin coating and geopolymer coating specimens with different resin content results in: Oxygen resin coating and metakaolin-based geopolymer coating both failed seriously under dry and wet cycles.However,the durability and chloride ion penetration resistance of the metakaolin-based geopolymer(EGP30)coating doped with 30wt% epoxy resin have been significantly improved.