Research On Resistance Performance Of Concrete To High Concentration Sulphate And Magnesium Salt Erosion

In order to study and explore the resistance performance and the mechanism of erosion damage ofconcrete under high concentration sulphate and magnesium salt double-erosion, With reference to theconcrete sulfate attack resistance test K method of GB/T749-2008,by soaking method erosion experimentwas carried out，erosion experiments with different types of cement mortar specimens soaked in differentconcentrations of magnesium sulfate solutions were carried out, and then, factors such as water-binder ratio,content of fly ash, the type of cement and so on, which affect the performance of concrete resistance tohigh concentration of magnesium sulfate erosion were analyzed, moreover, the appearance of the specimenshape and microstructure were also observed, the results of experiment showed that:(1) The Water/cement ratio, dosage of fly ash, curing ages, factors such as varieties of cement are onthe magnesium salt erosion resistance of concrete has a certain influence.Reducing water-binder ratioenhances the magnesium salt erosion resistance ability of the ordinary Portland cement specimen only inlow concentration erosion solution has a certain effect;Mixed with large dosage of fly ash to improveordinary Portland cement magnesium salt erosion resistance of the specimens;The longer the curing age,ordinary Portland cement magnesium salt erosion resistance of the specimens is higher;Sulphoaluminatecement mortar specimens with stronger than ordinary Portland cement mortar specimens of magnesium salterosion resistance.(2) In low concentration double sulfate, magnesium salt erosion environment, reduce thewater-binder ratio to a certain extent, to improve the corrosion resistance of the specimens;Increases, thedosage of fly ash can obviously improve the erosion resistance of the specimens.(3) In high concentration sulfate, magnesium salt erosion double solution, sulphur aluminate cementand the corrosion resistance of mortar specimen was obviously higher than that of ordinary Portland cementmortar specimen, low water-binder ratio of sulphoaluminate cement specimen has a stronger ability toresist corrosion.(4) Magnesium salt erosion damage of specimen, whose character is: the surface appearance iscomplete, but strength is decreased obviously.The reason for this is that Mg2+and hydration products ofcement produces chemical reaction, generate no cementation ability of softening material, magnesiumhydroxide and hydrated magnesium silicate, weaken the strength of the specimens(5) In high concentration sulfate, magnesium salt erosion under the double damage the specimen,whose character is: the specimen surface dusting, severe spalling.The reason for this is that of doubleerosion solution Mg2+, SO2-4react with the cement hydration products, producing magnesium hydroxide,hydrated magnesium silicate and gypsum respectively, the erosion of the three products are intertwinedtogether, weaken the specimen surface bonding force and strength of cement stone, eventually led to thespecimen damage occurred.(6) Sulphoaluminate cement specimens in high concentration sulfate, magnesium salt erosion doublesolution showed a greater resistance to erosion ability, is the cause of sulphur aluminate cement specimenof high compactness, and specimens of Ca (OH)+2, and so can react with Mg2, SO2-4generates less erosionof the product, therefore, the specimen are more difficult to happen on erosion.