Experimental Study Of Chloride Ion Transport Properties In Post-Tensioned Prestressed Concrete Protection Mode

Reinforcement corrosion caused by chloride ions in post-tensioned prestressed concrete structure has been causing different degrees of influence,seriously affecting normal use of the structure and greatly reducing its bearing capacity,thus seriously affecting the service life of the structure.Based on the transmission mechanism of chlorine erosion in the cement material,and the chloride ion transferring in the protective layer of post tensioning prestressed concrete structure,this paper studied and the main contents and results are as follows.Studied the chloride ion's transport properties in post-tensioned prestressed concrete structure.Analyzed chloride ions' transmission properties in different metal corrugated pipe,grouting saturation and the mixture ratio of grouting.Obtained that metal corrugated pipe has played a very good block effect to the chloride ion's diffusion in deep layer.The area around the shell of pipe is in a more dangerous chlorine salt environment than outside the pipe in the same depth,and more easy to rust the steel strand.On the outside of the metal corrugated pipe,with the increase of depth,the chloride ion content of each point increased with the decrease of after first.The chloride ion content in the tube seam location is higher than others.Studied the chloride ion permeability of post-tensioned prestressed concrete structure in the interface conversion between metal corrugated pipe and the duct grouting.Mainly from three aspects:the initial chloride content,surface and chloride ion diffusion coefficient of chloride ion content,carried on the analysis,the initial chloride content of specimen interfacial zone with different mixing ratio both clearly has a rising trend.In later erosion,surface chloride ion content of ordinary mixing proportion cement grouting were increase significantly,while Y-80 type are maintained in the original level in both cementation interface and non-interface areas.The chloride ion diffusion coefficient of ordinary mix cement grouting were higher than Y-80 type.In the cement-wall non-interface area is not monotone decreasing like interface area.For ordinary mixing ratio's cement grouting,the chloride ion diffusion coefficient in interface area is significantly higher than the non-interface area,while a chloride ion diffusion coefficient of cementation interface area for Y-80 type was at the same level on the whole process.