Experimental Study On Improving The Durability Of Concrete In Coastal Environment

Corrosion of steel is the main reason for inducing the durability disease of concrete structure.Corrosion of reinforced concrete structures in coastal areas is particularly serious.The main factors affecting the durability of concrete in this environment are carbonation,acid rain erosion,and chlorine salt erosion.In view of the deterioration of concrete durability in coastal areas,many durability improvement measures have been developed,such as cathodic protection,concrete re-alkaliation,electrochemical dechlorination,electrodeposition repair,and addition of steel corrosion inhibitors,the corrosion inhibitor and the galvanic anode cathodic protection is most wildly used because of ease of use,cost-effective.In this paper,a mixed solution of sodium chloride and ammonium sulfate is used to simulate the chlorine salt and acid rain in the coastal environment.The spray and wet-dry cycles are used to simulate the salt fog and rain areas in the coastal environment.Synergistic blends of alcohols and carboxylates are blended with corrosion inhibitors and migrating corrosion inhibitors,and the galvanic anodes of zinc-based alloys to protect the reinforced concrete in coastal environments.The study was divided into three parts.In the first part,the effects of aminocarboxylates darex corrosion inhibitor and migrating corrosion inhibitors on the durability of concrete were studied,including appearance,mechanical properties,carbonation resistance,and chloride ion permeability resistance.In the second part,the effects of aminocarboxylates darex corrosion inhibitor and migrating corrosion inhibitors on the corrosion behavior of steel bars in concrete under different chloride concentrations were studied.The mechanism and performance of corrosion inhibitors were investigated.And a brief discussion of the selection of the electrochemical equivalent circuit of the steel/concrete system.In the third part,the aminocarboxylates darex corrosion inhibitor and migrating corrosion inhibitors and zinc-based alloy galvanic anodes were studied for the simulation of carbon steel electrodes in the simulated pore solution under different chloride ion concentrations,different pH values,and different time conditions.The influence of the corrosion behavior avoids the interference of the complex interfacial system of the concrete on the electrochemical results,and further clearly shows the protection mechanism and the protective performance of the protective measures.Tests on the performance of concrete have shown that both of aminocarboxylates darex corrosion inhibitor and migrating corrosion inhibitors can improve the durability of concrete,smooth and compact the concrete surface,slightly increase the compressive strength of the concrete,inhibit the carbonization of the concrete,and reduce the concentration of chloride ions at various depths of the concrete.The experimental study on the corrosion of rebar in concrete shows that aminocarboxylates darex corrosion inhibitor and migrating corrosion inhibitors can effectively reduce the corrosion rate of steel in concrete at different chloride ion concentrations,and can increase the concentration of chloride ions that cause initial corrosion of rebar.The critical value increases the threshold of corrosion of steel bars and delays the corrosion time of steel bars.It is worth noting that the darex corrosion inhibitor can play a good protective role against the sulfate and chloride salts in the concrete,the corrosion-inhibiting efficiency varies little with the chlorine ion concentration,and the average value is stable at about 45.7%.The migrating corrosion inhibitor shows low corrosion-inhibiting efficiency when the concrete is only eroded by sulfate.With the increase of chloride ion concentration,the corrosion-inhibiting efficiency gradually increases,and when the final concentration of chloride ions reaches 0.85 mol/L,it is stable at 45.6%.The corrosion test of the carbon steel electrode in the simulated pore solution shows that the aminocarboxylates darex corrosion inhibitor can achieve better corrosion resistance in a neutral environment,and its rust-inhibiting efficiency first increases and then decreases with the increase of chloride ion concentration.When the content of the darex corrosion inhibitor is 1%,the rust resistance efficiency is 98.49% at a concentration of 0.6 mol/L of chloride ion,its rust-inhibiting efficiency is stable with time;The aminocarboxylates migrating corrosion inhibitors can obtain better rust-inhibiting effect in the alkaline environment,and the rust-inhibiting efficiency increases with the increase of chloride ion concentration.When the content of the migrating corrosion inhibitors is 1%,the rust resistance efficiency is 65.00% at a concentration of 0.6 mol/L of chloride ion.But due to the alkaline environment,the migrating corrosion inhibitors volatile strong and the rust-inhibiting efficiency may be greatly reduced with time,while the rust-inhibiting efficiency is relatively stable in a neutral environment;zinc-based galvanic anode can achieve better performance in a more alkaline environment.The rust-inhibiting effect of the rust-inhibiting efficiency is stable over time,reaching 82.05% at a concentration of 0.6 mol/L chloride ion.