Study On Corrosion Resistance Of Admixture Sand Under Electric Field-Low Temperature-Chloride And Sulfate

In this paper,limestone powder,fly ash single or double admixture cement mortar as the research object,with normal temperature,low temperature,electric field,low temperature-electric field coupling of sodium chloride,sodium sulfate mixed into the erosion environment as erosion conditions,the apparent morphological changes of admixture cement mortar,mass change rate,compressive strength and other macroscopic properties were evaluated.At the same time,the cement mortar specimens under each erosion environment were tested by SEM,EDS,XRD and other microscopic tests,and the evolution law of chloride and sulfate resistance of admixture cement mortar under each erosion environment was analyzed and compared.Under normal temperature–sodium chloride and sodium sulfate erosion environment,chloride had obvious inhibitory effect on the sulfate attack of the four groups of specimens,and the strength of the specimens did not decrease significantly.The gypsum content in the erosion products was low.Under the environment of low temperature-sodium chloride and sodium sulfate attack,chlorine salt has little effect on the sulfate attack resistance of mortar mixed with limestone powder,fly ash and fly ash alone.The limestone powder group was obviously affected by temperature.Four groups of specimens were subjected to TSA sulfate attack at 150 d.Under the environment of electric field-sodium chloride and sodium sulfate erosion,the presence of electric field will greatly accelerate the erosion rate of specimens.Double-doped limestone powder,fly ash and single-doped fly ash can improve the chloride and sulfate corrosion resistance of cement mortar to a certain extent,but single-doped limestone powder will make specimens more vulnerable to erosion.Under the coupling effect of electric field and low temperature,the erosion degree of the specimen was not significantly different from that under the electric field or single low temperature environment.Chlorine salt still showed a strong inhibitory effect on sulfate erosion.At the end of erosion(150d),the peak value of Fs diffraction peak in the specimen declined significantly.Double-doped limestone powder and fly ash did not significantly help to improve the mixed corrosion resistance of chloride and sulfate,but considering its economic and environmental protection,double-doped limestone powder and fly ash still had certain social value.Under different long-term immersion erosion mechanisms of sodium chloride and sodium sulfate,the erosion degrees of specimens under three erosion conditions of low temperature,electric field and electric-low temperature coupling were not significantly different.The reason was that the erosion laws of specimens under single low temperature and single electric field were basically similar.In the early stage of erosion,the erosion degree of gypsum sulfate was low,and in the late stage of erosion,the specimens were subjected to TSA sulfate erosion due to the influence of electric field and low temperature.Therefore,there is no obvious accelerated erosion phenomenon on the specimen under the coupling effect of electric field and low temperature.