Experimental Study On The Effect Of Strong Base Anion Exchange Resin (AER) On The Resistance Of Mortar To Chloride Ion Permeability

The corrosion damage of chloride ion to reinforced concrete is one of the main types of damage to concrete structure.Therefore,it is necessary to study the ability of concrete to resist the diffusion of free chloride ions and enhance the binding capacity of chloride ions.In this paper,strong base anion exchange resin(AER)was used as a chloride ion transport retardant material to add into mortar.The influence of AER on chloride ion penetration resistance of mortar was studied by the change of content and soaking time.The anion exchange resin was mixed with fly ash(FA)and silica fume(SF)by ball milling to form a ternary admixture with a particle size of 75 ?m and then added to the mortar.Firstly,the effects of pure AER particles on the work performance,mechanical properties and hydration process of cement paste were studied.The results show that the AER particles have little influence on the work performance,mechanical properties and hydration process of cement paste in the small content range of about 3 wt%.However,in the case of large content,the fluidity of the cement paste is reduced,the cement setting time is delayed,the bending resistance of the cement paste sample is reduced,the compressive strength is lowered,and the hydration heat of the cement is lowered.The effect of ternary admixture on the chloride ion penetration resistance of the mortar was further studied.The results show that when the AER content is within 3 wt% when the SF content is kept at 5 wt% and the FA content is 10 wt%,the effect of improving the chloride ion penetration resistance of the mortar is remarkable.If the amount is too large,the performance improvement is not obvious or decreases.In order to further improve the superimposed effect of the three on the chloride ion penetration resistance of the mortar,it was found that the mortar has better anti-chloride ion permeation performance when the SF content is 10 wt%,the FA content is 30 wt%,and the AER content is 3 wt%.However,from the viewpoints of mechanical properties,compactness and microstructure of mortar,the comprehensive performance of SF content of 5 wt%,FA content of 10 wt% and AER content of 3 wt% is better.Further analysis shows that the positive factors affecting the chloride ion penetration resistance of the mortar in the ternary admixture include its own adsorption to chloride ions and the internal pores of the filled mortar.The unfavorable factor is that It has poor compatibility with cement and can affect the hydration of cement to a certain extent.The SF and FA in the ternary admixture improve the microstructure of the cement paste and interfacial transition zone through the pozzolanic effect and filling effect,and improve the compactness of the mortar,thereby improving the mortar strength and durability.Finally,the time decay model of chloride ion diffusion coefficient with AER content was established by data fitting and its accuracy under established conditions was verified.