Research On Coating Protection Of Concrete In Marine Environment

At present,durability of steel-ion concrete is becoming more and more prominent in mating environment.Damage of construction induced by durability is serious,which brings huge economic loss to our society.As a kind of material improving durability of concrete effectively,concrete protective coatings are paid more attention.But now, research on properties of concerete coating in marine environment is not much,and the tests and evaluation methods about capability and protective effects of concrete protective coatings are not mature,which restrict the healthy development and engineering application seriously.So the research on properties of concerete coating in mating environment has important value of theory and practice.The paper choice three typical coatings to research,these coatings are aliphatic polyurea coating,cement-based polymer coating and polyurethane coating.Firstly,the water absorption and impermeability tests of these coating concrete were studied.These tests research the ability of these concrete protective coatings prevent seawater into concrete in marine environment.The water absorption test shows that the 24h water absorption rates of concrete with aliphatic polyurea coating,cement based polymer coating or polyurethane coating are 0.058%,0.4%and 0.095%.Their water absorptive ratios(their water absorption rate compare with the benchmark concrete's) are 0.82%,5.70%and 2.63%.The impermeability test shows that in the test of the three coating concrete step by step in the pressurized to 1.5 MPa,can maintain 24h do not appear leakages.At the higher pressure of 3.0 MPa,aliphatic polyurea coating concrete and polyurethane coating concrete can maintain 9h do not appear leakages and cement-based polymer coating concrete can maintain 7.5h.Test results confirmed that in the marine environment,aliphatic polyurea coating,cement-based polymer coating and polyurethane coating can effectively improve the water absorption and impermeability of concrete,aliphatic polyurea coating of the most good,followed by polyurethane coatings,cement-based polymer coating lower.Secondly,the resistance to chloride penetration of concrete protective coating of aliphatic polyurea,cement-based polymer,polyurethane by rapid chloride penetration test (RCM) and nature soak method was studied.Research results show that,RCM method has correlation to nature soak method,correlation coefficients are above 0.900.Both methods can evaluate resistance to chloride diffusion of the above coating-concrete effectively.In the condition of RCM method,concrete protective coatings could improve the resistance to chloride penetration of concrete.And the resistance value increases with the brush coating time accretion of coating.In the condition of nature soak method,the law of chloride diffusion confirms to function of first order linear attenuation,correlation coefficients are above 0.989.And,chloride diffusion coefficients of concrete and coating-concrete have correlation to dipped period,the linear correlation coefficients are above 0.920.At last,the applications of AC Impedance Spectroscopy(ACIS) in study of concrete protective coating are discussed in this paper.The structure model of concrete protective coating system of aliphatic polyurea,cement-based polymer,polyurethane is applied to describe the ACIS behavior and draw Nyquist figs.It is show that the high frequency arc of concrete protective coating system is a semicircle,based on testing results,the parameter Rf used to describe the above concrete protective coating materials close-grained capability is fixed on.The varieties of concrete inner micro structure are educed by AC Impedance Spectroscopy comparison between before and after chloride diffusion.And it in line with the chloride ion diffusion model of coating concrete system.Compared to rapid chloride penetration test,parameter△|Z|_max is used to denote the resistance to chloride penetration,and linear correlation coefficients are above 0.952.The above researches provide theory reference and technology support for establishing test and evaluation about capabilities and protective effect of concrete protective coatings,and accelerate the development and engineering applications of concrete protective coatings.