Experimental Study On Effect Of Derusting Method On Bond Behavior Between Steel Bar And Concrete

Bond behavior can be affected by many factors between steel bar and concrete,such as freeze-thaw cycle,dry-wet cycle,sustained load and corrosion of steel bar.There are a lot of experimental studies on these aspects all over the word,but there is little research on the influence of rust removal methods on the bond behavior between steel bar and concrete.In practice,the project may be shut down because of some force majeure factors.Steel bars exposed outside the concrete may rust due to environmental impact,the cross sectional area of steel bar decreases after corrosion,and the stress changes greatly under the condition of the same load,and corrosion affects the bond behavior between steel bar and concrete.If the rust problem is not solved when the project is resumed,it will definitely affect the quality of the whole project.Therefore,suitable rust removal methods should be selected to remove the corrosion of reinforcement.To study on the influence of various rust removal methods on the bond behavior can provide some suggestions for selecting suitable rust removal methods in practice.In this paper,the corrosion of HRB400 with diameters of 14,18,22 and 25 mm is carried out under natural environment,then three corrosion rates are distinguished,and angle grinder,rust remover and shot blasting machine are used to remove rust,central pull-out specimens are made of premixed concrete,and the bond behavior between steel bar and concrete under different conditions are studied.The experiment studies:(1)reduction of rib height of steel bars after various derusting methods.(2)the influence of rust removal method,corrosion rate and steel bar diameter on the bond strength and peak slip of specimens respectively,and the reason of various factors on the bond behavior of specimens.(3)bond-slip constitutive relationship between steel bar after rust removal and concrete with different diameters and corrosion rates,and the function formula of bond-slip constitutive relation.The research results show that:(1)The rib height of steel bar is weakened least by angle grinder rust removal,rust remover and blasting machine are similar to the degree of rib height weakening.(2)Splitting failure occurred on specimens with diameter 14 mm steel bar andrust removal by angle grinder,pull-out failure occurred on specimens with other rust removal methods.Splitting failure occurred on specimens with diameter 18,22,25 mm.(3)With the increase of the diameter of steel bar,the width of crack increases after the splitting.(4)Specimens with steel bar use angle grinder have maximum bond strength and minimum peak slip.With the increase of corrosion rate,the bond strength decreases and the peak slip increases.With the increase of the diameter of steel bar,the bond strength and the peak slip decreases.