Investigation Of Corrosion Resistance To Salinized Soil Attack On Binary Rapid Repair Material Modified By Granulated Blast Furnace Slag And Nanosilica

Salinized soil contains high concentration of corrosive salts,especially soluble sulfates and chlorides.Concrete structures such as highways,tunnels,and airport pavements more vulnerable suffer from premature deterioration or damage caused by the combined service life,mechanical load and environmental factors in salinized soil areas.Without timely treatment,the damage will rapidly magnify,seriously affecting its operation safety and service life.So,the preparation of cement-based rapid repair materials resistant to salinized soil erosion could extend its service life and reduce the cost of repeated repairs.However,due to the composition and reaction mechanism of traditional repair materials,its application in saline soil environment was limited.Therefore,the binary system of sulphoaluminate cement(CSA)-ordinary portland cement(OPC)was chosen as the basic system.In addition,nanosilica(NS),granulated blast furnace slag(BFS)and chemical admixtures were added to modify the composite system,and the erosion and destruction rules and mechanism of the composite system in different corrosion systems and environments were studied.The aim was to obtain a cement-based quick repair material suitable for salinized soil areas in this paper.Firstly,0.5wt.%,1.0wt.%,1.5wt.% and 2.0wt.% NS were added into the binary system with appropriate proportion,and the optimal proportion of ternary system was selected by comparing the setting time,mechanical properties and microstructure.Then 10 wt.%,20 wt.%,30 wt.% and 40 wt.% BFS were added to replace the ternary system to form the quaternary composite systems,and the resulting six kinds of composite systems of binary system,ternary system and quaternary system were cured to 28 d in the standard curing room.Next,the long-term immersion and drying-wetting cycles corrosion systems were used to semi immerse in the compound solution of sodium chloride,sodium sulfate and sodium chlorium-sodium sulfate composite solution to the corresponding age,and the technical indexes such as mass change,corrosion resistance coefficient,relative dynamic elastic modulus and chloride ion content were tested.Finally,the microscopic research method of X-ray diffraction analysis(XRD)was used to analyze the composition of hydration products of various composite systems under different erosion environments and the erosion mechanism was explored.The following results could be drawn:(1)The erosion damage rules of the specimens were basically similar under the longterm immersion and the drying-wetting cycles.The erosion degree of the specimens was the least in the chlorine salt,the most serious in the sulfate,and the relatively light in the composite salt,indicating that the chloride salt has a delaying effect on the erosion damage of the sulfate.(2)The system mixed with appropriate amount of NS and BFS owns excellent corrosion resistance to salinized soil,and the most suitable amount of slag was 10 ~ 20 wt.%.(3)In the erosion process of the specimens of different systems half-immersed in the salt solution,the drying portion and the immersed portion of the specimens had different performances.And the damage areas of the specimens were mainly concentrated near the efflorescence zone above the liquid surface.(4)Through the comparative analysis of the test results,6 kinds of composite systems under different corrosion solution of erosion,G0 and G10(BFS content of 0 wt.% and 10 wt.%)of the system of erosion damage the lightest,S(binary system)and the G20(BFS content was 20 wt.%)system were the second,and the systems of G30 and G40(BFS content of 30 wt.% and 40 wt.%)were the worst.