| At present,study on the corrosion resistance of reinforced concrete structures under the combined action of sulfate and chloride is more,but the study on corrosion resistance of magnesium salt,sulfate and chloride are relatively few.Regions both belong to the western region,Jiuquan area of Gansu province belongs to heavily saline soil area,Golmud area of Qinghai provin ce contains a large number of Saline Lake.In the West Saline Lake area and heavily saline soil area,the corrosion of ordinary portland cement reinforced concrete is very serious.Brine Erosion has caused a serious threat to the durability and safety of reinforced concrete.Magnesium cement has not modified the performance of bittern resisting corrosion,while the western Saline Lake also has a large number of raw materials of magnesium cement.Therefore,the research on it is of great significance to the development of Saline Lake in Western china.However,Magnesium cement has strong corrosion to steel bar,the coating is used to protect the steel bar.Study on anti bittern corrosion of magnesium cement reinforced concrete in the western area of has theo retical significance and social economic value.In this paper,six groups of reinforced concrete block s were designed respectively,which are Mg-GHT(magnesium cement concrete-epoxy resin coated steel bar),Mg-B(magnesium cement concrete-bare steel),the P.O.1-GHT(Portland cement concrete with ratio 1-epoxy resin coated steel bar),the P.O.1-B(Portland cement concrete with ratio 1-bare steel),the P.O.2-GHT(Portland cement concrete with ratio 2-epoxy resin coated steel bar),the P.O.2-B(Portland cement concrete p with ratio 2-bare steel).The corrosion resistance of reinforced concrete based on different cementitious materials was studied by electrochemical method,electric-resistivity method,rapid corrosion test and field exposure test.The research content and results are as follows:1.The block was immersed in the coupling solution with long time for electrochemical quantitative detection regularly.Corrosion behavior of chloride,sulfate and magnesium in concrete was studied by polarization curve a nd AC impedance analysis.The results showed that the corrosion resistance of Mg-GHT is better than that of P.O-B in the bittern erosion environment.2.In order to simulate the actual environment in Jiuquan and Golmud,considering the factors of freeze-thaw cycle and ultraviolet radiation,the indoor large circulation test with rapid corrosion and field exposure test were designed.The ultrasonic velocity,mass and bar resistance of concrete were tested periodically.The relative dynamic elastic modulus of concrete ?1 and the relative mass evaluation parameters ?2 of reinforced concrete were taken as the basic durability evaluation index.In order to be able to reflect the degree of corrosion of reinforced concrete,the no rust average cross section evaluation parameter ?3 of rebar and the damage degree evaluation parameter ? of reinforced concrete were designed.The corrosion law of reinforced concrete in chloride,sulfate and magnesium salt was analyzed.The results showed that the corrosion resistance of magnesia cement coating reinforced concrete is better than that of Portland cement exposed reinforced concrete in bittern the erosion environment.3.Combined with EDS energy spectrum analysis and SEM scanning electron microscope,the corrosion products of reinforced concrete were analyzed,and the microstructure and composition of the products were determined.The corrosion mechanism and law of reinforced concrete were further analyzed.Based on the above research,it is concluded that the magnesium cemen t coated reinforced concrete is more superior than the Portland cement exposed reinforced concrete in the environment of Saline Lake and the saline soil.Due to the relative density of magnesium cement concrete,it restricts the penetration of corrosive io ns from the external environment.Therefore,in the area rich in magnesium cement raw material can consider to use magnesium cement concrete. |
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