| The reinforced concrete structure historical buildings have deteriorated at different degrees,which was generally becoming another issue of cultural heritage restoration.Ingress of chloride ions and carbonation of concrete will cause the corrosion of reinforcement and the spalls of concrete.In the repair techniques for reinforced concrete,electrochemical rehabilitation is a technique that is suitable for the stage that the the damage of concrete is relatively light.After electrochemical rehabilitation,the surface of the architectures is almost no influenced,therefore it is very appropriate protection method for the preservation of cultural relics and excellent historical buildings.Based on the principles of electro-migration,this study chose the ?aminopropyltriethoxysilane(APS),an amino-silane as electrolyte and its inhibitive effect,mechanism,electrochemical rehabilitation effect and the durability developing effect were investigated systematically.The results show that APS can bring the inhibitive effectiveness and develop the durability of concrete.This study provides a theoretical and practical basis for the subsequent application of this type of material in electrochemical rehabilitation.The specific research work includes the following contents and conclusions:(1)The inhibition effectiveness of APS in non-carbonated and carbonated simulating concrete pore solution were explored.In the experiment,the electrochemical measurement and surface analysis were performed.The results show that APS brings higher inhibition efficiency in carbonated concrete pore solution.The difference in inhibition efficiency is related to the various mechanisms of APS adsorption mechanisms on the iron surface:the adsorption energy of APS is lower in highly alkaline non-carbonated simulating concrete pore solution.Besides,APS promotes the precipitation of calcium hydroxide,but the looser membrane can not stop the pitting corrosion.In the sodium bicarbonate/sodium carbonate simulated pore solution with low alkalinity,the adsorption of APS on the iron surface is a combination of chemical and physical adsorption,making the adsorption more stable.(2)The migration quantities of APS into the cement mortar under the electric field and natural diffusion are compared.APS can migrated to the cathode side under the electric field and the concentration of APS in the cement mortar is higher than the case in natural diffusion.However,the electrical migration efficiency of APS is sensitive to the pH environment and its migration efficiency is higher in carbonated cement mortars.(3)The study compares the chlorination removal effect in carbonated and noncarbonated cement mortars with different electrolytes,which include deionized water,saturated lime water,sodium carbonate,and different concentrations of APS.The results show that the chloride ion transport number in carbonated cement mortar is higher.Deionized water,saturated lime solution and APS have better chloride extraction efficiency than sodium carbonate.Deionized water,saturated lime solution and APS tend to increase the voltage during the energization of the carbonated specimens.The electrochemical treatment increased the content of hydration products in the cement mortar and calcium hydroxide re-generated in the carbonized specimens.(4)In this study,the electrochemical protection effect and the effectiveness of developing concrete durability of APS were compared with the reported electromigration corrosion inhibitor.It was found that APS had obvious advantages in improving the hydrophobicity of the concrete surface,developing the ability to resist chloride ions ingress and resistance of carbonization,indicating that APS can efficiently provide the resistance ability to the corrosion factors.When APS was applied in electrochemical treatment,it can remove chloride ions effectively and maintain higher resistance of cement mortar.However,it shows limited effect on alkalinity recovery.Thus,it needs to be used in conjunction with other electrolytes for the re-alkalization process. |
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