Study On Mechanism Of Anti-chloride Ion Permeation Of GO Modified Coral Sand Mortar

South island reef construction is far away from the mainland,especially emergency construction is subject to the constraints of sea conditions and transportation distance.Taking local materials and effectively using the coral sands of the widely distributed coral reef flats and lagoons is an effective way to solve this problem.However,the harsh marine environment such as high salt,high temperature and high humidity has an erosive effect,especially the penetration of chloride ions and erosion of coral sand structures.Therefore,the construction of "safety islands" and "ecological islands" must consider blocking the penetration of chloride ions,and adopting a very small amount of graphene oxide(GO)into the coral sand mortar to maximize the performance of the coral sand mortar in blocking the penetration of chloride ions,to meet the requirements of engineering construction.Based on the comparison of river sand mortar,this paper takes coral sand mortar as the research object.Based on the analysis of the difference of coral sand particles,the improvement of coral sand mortar with the excellent performance of GO,the work performance test,the rapid chloride ion migration test,and the XRD experiment are carried out,SEM experiment and IPP image processing to perform microscopic characterization,and establish the correlation analysis between the two on the change law of microstructure and migration coefficient,so as to reveal the mechanism of GO modified coral sand mortar blocking chloride ion penetration,the main content of the study and conclusion as below:Based on the comparison of river sand mortar,this paper takes coral sand mortar as the research object.Based on the analysis of the difference of coral sand particles,the improvement of coral sand mortar with the excellent performance of GO,carry out work performance test,rapid chloride ion migration test,combine XRD experiment,SEM experiment and IPP image processing for microscopic characterization,establish the correlation analysis between the microstructure and chloride ion migration coefficient,and reveal the mechanism of GO modified coral sand mortar blocking chloride ion penetration.The main research content And the conclusion is as follows:(1)Analyzed the physical properties and mineral composition of coral sand and river sand particle shape,gradation and water absorption: the coral sand particles have irregular shapes,many sharp corners,and high surface roughness,which is usually 30～150μm.The shape of river sand tends to be elliptical,with high surface flatness and compactness,without obvious pores;the water absorption rate of coral sand is 12%,while that of river sand is 2%;aragonite and calcite are the main mineral components of coral sand,and quartz is the main component of river sand.(2)Through consistency test,fluidity test and water retention test,the influence characteristics of GO on the performance of mortar are studied:the blending of GO with mortar increases the consistency of the mortar,reduces the fluidity of the mortar,improves the water retention of the mortar,and has the effect of thickening and water retention.(3)Through the chloride ion penetration test,the improvement law of GO blocking the penetration of chloride ion in the mortar was studied: the retardation performance is related to the amount of GO blending,but the relationship between the two is non-linear,and the relationship is positive and then negative.The amount of 0.02wt%～0.03wt% is an important change node;28d and 56 d coral sand mortar mixed with 0.02wt% GO increases the chloride ion penetration performance by 39.43% and 48.93%,and is compared with the ordinary without GO under the same process conditions.(4)The microscopic characterization was obtained through XRD experiment,SEM experiment and IPP image processing:Compare the progress of hydration reaction and the change trend of hydration products before and after GO addition,hydrated crystal shape,the degree of compactness of the interface transition zone,the plugging morphology of coral sand,the generation and development of internal cracks,by analyzing the change law of microstructure and migration coefficient,and establishing the correlation analysis between the two,the mechanism of GO-modified coral sand mortar blocking the penetration of chloride ions is revealed.(5)By evaluating the effect of GO improving coral sand mortar,the feasibility of practical engineering application was demonstrated;the GO content,input cost and the degree of improvement in the improvement process were explored,and the application prospect of GO was evaluated.