Study On Properties And Applications Of Toughened Waterborne Epoxy Coated Steel Bars

Corrosion of steel bars in concrete structures under chlorine salt environment has become the main reason that threatens the safety of structures and reduces the service life.The loss caused by building damage caused by corrosion of steel bars is very serious every year.Coated steel bars as a simple and effective technical means to improve the durability of concrete structures under harsh environment have increasingly received extensive attention from scientific and engineering circles at home and abroad.Epoxy resin coating is considered to be an effective measure to prevent corrosion of steel bars among all kinds of coatings.The shortcomings of epoxy resin coating such as high brittleness,easy cracking and aging have not been well solved although epoxy resin coating can improve corrosion resistance of steel bars on the whole at present.In addition,epoxy resin coating can also reduce the bonding performance between steel bars and concrete.It is of great significance to study and prepare a waterborne epoxy coating that can overcome the defects of traditional epoxy resin coating for improving the durability and service life of concrete structures in chlorine salt environment.Toughened waterborne epoxy coating and coated steel bar are prepared by composite antirust powder filler and various additives and their properties are studied in this paper based on the existing modified epoxy emulsion of the research group.The main research contents are as follows:?1?The influence of different mineral powder filler components on the corrosion resistance of the coating was studied.The impact resistance and flexibility of toughened waterborne epoxy coating were tested.The corrosion resistance of toughened waterborne epoxy coating was tested by electrochemistry.The results showed that the coating with20%1200 mesh mineral powder filler had the best corrosion resistance effect.The corrosion current of the coating changes little and the current kept below 0.2?A?cm^-2within 160 days.The corrosion resistance time of the coating is more than 1.6 times that of the common epoxy coating.The coating has excellent rust resistance and corrosion prevention functions.?2?The performance test of toughened waterborne epoxy coated steel bar?steel rod?was carried out.The synergistic deformation ability of the coating and steel was studied through tensile test of coated steel bar.The results show that the coating steel bar prepared by adding different components of mineral powder filler has obvious cracks only when the elongation rate is up to 1.31%.The toughened epoxy coating can meet the tensile requirement of 0.5%for prestressed steel bar in the production of prestressed pipe pile.The wet adhesion test and cold bending test of coated steel bars show that the ductility and strength of toughened epoxy coating with mineral powder as filler are better than those of common epoxy coating.?3?Pull-out tests of toughened waterborne epoxy coated steel bar and concrete were carried out to study the bonding properties of coated steel bar and concrete,and the bond-slip curves of toughened waterborne epoxy coated steel bar and concrete were obtained.The influences of filler type,component and steel bar type on the bonding strength properties of coated steel bar and concrete were compared and analyzed.The results show that the ultimate bond strength of toughened epoxy coated steel bar with 400mesh mineral powder filler is higher than that of coated steel bar with 1200 mesh mineral powder filler,and the bond strength between coated steel bar and concrete with 30%400mesh mineral powder filler is the best.The bond strength between toughened epoxy-coated steel bar and concrete developed is better than that of uncoated steel bar.?4?Based on the pull-out test,the finite element simulation of bonding performance between toughened epoxy coated steel bar and concrete was carried out by Abaqus software.The cohesive force model between toughened epoxy coating and concrete is defined to simulate the bond-slip performance between coating and concrete.The pull-out test of toughened epoxy coating reinforced steel and concrete is simulated by dividing concrete assembly at the interface of Abaqus software.The comparison results show that the displacement corresponding to the peak load in the test results is within 15%of the comparison error with the simulation results,which indicates that the cohesion model used in this paper can reasonably carry out the simulation analysis of the pull-out test.