Studies On Improving Carbonation Resistance Of Concrete With Graphene Oxide Modified Epoxy Resin Coating

In atmospheric environment,steel corrosion caused by concrete carbonation is the main factor affecting the durability of concrete structure.Organic coating on concrete surface can effectively prevent the invasion of CO₂ and improve the carbonation resistance of concrete.However.the organic coating is easy to aging,which leads to the gradual reduction of the protective ability of concrete.Previous studies have shown that the incorporation of ordinary granular inorganic nano materials can improve the protective performance of coatings and slow down the aging of organic coatings at a certain extent.In this thesis,a new type of flake nano material-graphene oxide（GO）was selected to be applied to organic coatings in order to enhance the capability of resisting carbonization and aging of composite coatings.In this thesis,epoxy zinc rich primer and epoxy resin topcoat were selected as the coating system.GO and deionized water were mixed or Ti O₂ grafted GO were used to disperse.0.1%,0.3%and 0.5%（weight ratio）GO were added into epoxy resin to prepare composite coating.Taking composite coating concrete as the object of study,the carbonation resistance and aging resistance of GO-modified epoxy resin coated concrete were studied by artificial weathering aging test and accelerated carbonation experiment.The mechanism of GO resistance to carbonization and aging resistance of epoxy resin coating on concrete was analyzed from scanning electron microscope and infrared spectrum.According to the experimental results,the carbonation depth prediction model of GO-modified epoxy resin coated concrete was finally established.The main results are as follows:（1）Nano-GO can effectively improve the carbonization resistance of epoxy coatings.The results show that the two dispersion methods can improve the carbonation resistance of epoxy resin coated concrete:Ti O₂+GO+epoxy resin coating>GO+epoxy resin coating>blank epoxy resin coating.When GO content is 0.3%,the two coatings have the best anti carbonization performance.After 7 days of accelerated carbonization,compared with the blank epoxy resin coating,GO+epoxy resin coating and Ti O₂+GO+epoxy resin coating increase by 37.3%and 50.2%respectively.The modification effect of GO on epoxy resin depends on the dispersion effect of go in epoxy resin.Nano-GO can not only fill the micropores in epoxy resin and fractures can also provide barrier effect,making the diffusion path of CO₂ more tortuous.（2）Nano-GO can effectively improve the UV aging resistance of epoxy coatings.Through the comparison of carbonation resistance of 0.3%GO-modified epoxy resin coating concrete after different UV accelerated aging time,the improvement effect is as follows:Ti O₂+GO+epoxy resin coating>GO+epoxy resin coating>blank epoxy resin coating.After 14 days of UV aging,compared with uncoated concrete,Carbonation resistance of concrete coated with the blank epoxy resin,GO+epoxy resin and Ti O₂+GO+epoxy resin coatings increased by30.5%,56.4%and 65.4%respectively.The good interface adhesion between GO and epoxy resin,the barrier effect of GO and the UV shielding effect of Ti O₂ greatly improved the UV aging resistance of the composite coatings.（3）Based on Fick’s first law,the prediction model of carbonation depth of GO-modified organic coating concrete before and after aging is established by analyzing the existing prediction models of concrete carbonation depth.The life prediction of coating concrete without considering aging and ultraviolet accelerated aging is carried out.It is found that GO can greatly improve the carbonation resistance and ultraviolet aging of organic film-forming coating concrete Performance.（4）After UV accelerated aging,the average ceiling cost of blank epoxy resin,GO+epoxy resin and Ti O₂+GO+epoxy resin coatings is 0.51 yuan/m²,1.19 yuan/m² and 1.04yuan/m² based on the concrete and carbonation depth of 15mm.In terms of economy,due to the expensive nature of GO,there is a slight shortage in cost performance.However,with the development of GO industrialization,there is still a bright future for GO to be used in organic coatings in the future.There are 35 figures,20 tables and 104 references.