Carbonation resistance of concrete coating under flexural tensile stress and nitric acid erosion
To study the carbonation-resisting protection effect of the coating on the concrete structure under flexural tensile stress and nitric acid erosion,three kinds of concrete coatings including mixed epoxy resin primer,heavy anticorrosive primer for highway,and 1103 epoxy general primer were selected,and the influence of three coating systems and coating thickness on the carbonation resistance level of concrete was considered.The rapid carbonation test of 100 mm(length)Xl00 mm(width)× 400 mm(height)standard prismatic concrete specimens under the coupling effects of nitric acid erosion and flexural tensile stress in the laboratory was carried out.The phenolic phthalein indicator method and the pH measured by simulated pore solution made of layered powder were used to analyze the influences of flexural tensile stress,nitric acid erosion,and carbonation time on the carbonation of uncoated concrete structures and concrete structures with different coating types and thickness.The formula for calculating carbonation depth of concrete structure under bending tensile stress grade and nitric acid solution concentration under standard carbonation conditions in laboratory was obtained respectively.Based on the pH measured by simulated pore solution made of layered powder combined with the theory of equivalent concrete thickness of coating,a prediction model of coating carbonation life was proposed.The results show that with the increase of erosion time,both nitric acid erosion and flexural stress increase the carbonation efficiency,and the effect of lower concentration nitric acid solution and higher grade flexural stress are more obvious,and the effect of higher grade flexural stress is more significant.A comprehensive carbonation model considering the concentration of nitric acid solution,flexural stress level and concentration of CO2 is proposed.Under the protection of the three coatings,the concrete test blocks are still eroded by CO2 and nitric acid,but the degree of erosion is greatly reduced.When the coating thickness is the same,1103 epoxy general primer has the best anti-carbonation protection effect,followed by mixed epoxy resin primer,and highway special heavy anti-corrosion primer has the worst anti-carbonation effect.The anti-carbonation effects of the coatings are primarily provided by its sealing functions,which are different due to the differences of the crack-sealing property,adhesion and acid resistance.The research results are of significance to the selection of protective coatings for concrete structures in atmospheric environment and provide a theoretical basis for quantitative analysis of anti-carbonation protective properties of coatings.5 tabs,9 figs,32 refs.
tunnel engineeringcoatings protectionrapid carbonation testconcreteflexural tensile stressnitric acid erosionprediction of life
NETL
NSTL
万方数据
维普
