Study On Application Of Organic Protective Inhibitor In Concrete

As a structural material,the reinforced concrete has been widely used in civil engineering structure for a long-term because of its incomparable advantages.At the same time,a lot of damaged and deteriorated reinforced concrete structures have gradually attracted people's attention.Therefore,the research on the problem of insufficient durability of the reinforced concrete has become a hot topic in the field of engineering.There are many external factors such as construction quality,cover thickness,property of the concrete material and structure type affecting concrete quality.The failure of reinforced concrete structure in advance is also caused by other varies factors,such as steel corrosion,carbonation,freeze thaw damage,alkali aggregate reaction and chemical erosion,among which the steel corrosion caused by chloride is the main reason.There are varies methods to control the steel corrosion being researched and used,such as cathodic protection,coating and conversion film technologies and the use of corrosion inhibitors is an effective means because of its ease of operation,low cost,and safety.In this paper,a kind of organic protective inhibitor containing amino ketone molecule was studied.The research started with the inhibitor's impact on durability of concrete through these tests: the compressive strength test,water absorption test,RCM test,chloride penetration test and accelerated carbonation test.Then the electrochemical behavior of steel in simulated concrete pore solution under the conditions of different concentrations of inhibitor and Na Cl,different p H and varies temperatures were investigated to characterize and quantify the effect of corrosion inhibitor on concrete.The corrosion inhibition efficiency was evaluated by means of weight loss,electrochemical impedance spectroscopy(EIS)and potentiodynamic polarization.Finally,chemical test,XRD test?SEM test and EDS test were carried out to further explain the reasons for the change of concrete durability and the protection for carbon steel.The conclusions were as following:Through the experiment of concrete,it was found that the mechanical properties of concrete were improved slightly due to the addition of organic protective inhibitor.The transmission of water,chloride,carbon dioxide in concrete restrained because the organic protective inhibitor reduced the porosity of concrete,thus the durability of concrete was improved to some extent.In addition,when the inhibitor was 3% ofcementing material,the mechanical properties of concrete was improved obviously and it was also economical.Through the experiment of steel corrosion,we found corrosion resistance of steel was improved significantly attributed to the addition of inhibitor and with the concentrations of inhibitor increase the inhibitor efficiency gradually increase.The maximum value reached 89.07% when the concentration was 4%.The new inhibitor was a kind of anodic inhibitor which suppressed the anodic process by chemisorption on the steel surface and it displayed good corrosion resistance for steel at different concentration of sodium chloride.The inhibition efficiency was calculated to be65.62%?80.06%?and 66.30% at the 2%?3.5%?5% Na Cl,respectively.Alkaline environment was helpful to improve the corrosion resistance of steel and p H11.3 was the most suitable working condition for the new inhibitor in which the adsorption capacity of inhibitor is largest.The inhibition efficiency under different temperature was in the order of 25?>35?>40?>20?>30? and the maximum efficiency was 81.32%at 25? which may be because this temperature was most conductive to the formation of compact protective film.At last,some microscopic tests were carried on.The inhibitor molecules can react with calcium hydroxide and produced colloid substance,but not with distilled water or sodium hydroxide colloid.XRD test proved that the organic protective inhibitor can promote cement hydration reaction which resulted in the increasing of concrete density.SEM test further proved that the inhibitor can form a protective film on the surface of steel,which can protect the steel bar from chloride ion erosion.