Experimental Study On Mechanical Properties Of Self-Compacting Recycled Concrete Beams Under Load And Corroded

With the increasing national requirements for energy conservation and environmental protection,and based on the current situation of the bridge structure being complex and diverse,the application of self-compacting recycled concrete in bridge engineering will have good engineering application prospects,but due to the low tensile strength of self-compacting recycled concrete strength,which induces the safety of self-compacting recycled concrete bridge structure under the influence of chloride corrosion and load,will inevitably affect the application prospects of self-compacting recycled concrete.In this paper,combined with the National Natural Science Foundation of China project "Prestressed high-performance recycled concrete flexural properties and design theory research"(51608331),6 self-compacting recycled concrete beams and 6 ordinary concrete beams were tested under rust and corrosion after the flexural performance test,the effect of corrosion and load coupling on the flexural performance of self-compacting recycled concrete beams was studied.The main research contents and conclusions of the paper are as follows:(1)Through continuous load and accelerated corrosion tests on concrete beams,the effect of load level on the corrosion of steel bars in the beams was studied.Statistical analysis was used to analyze the surface characteristics of corroded steel bars in the beam.The results show that: The increase of the load level will increase the actual corrosion rate of the steel bars in the beam,and the unevenness of the surface corrosion tends to be obvious;The pit length and pit depth of the steel bars are distributed on the surface of the steel bars with fractal characteristics.The fractal dimension increases with the actual corrosion rate,and the fractal dimension of self-compacting recycled concrete beam is larger than that of ordinary concrete beam..(2)Through continuous load and accelerated corrosion tests on the beam,the effect of the load level on the deflection of the beam and the rust expansion cracks on the surface was studied.the result shows that: The increase in load level accelerated the growth of the deflection of the corroded beam and the width of the surface rust expansion cracks,and through the study of the corroded beams under the same load level,it was found that the deflection and the width of the rust expansion cracks of the self-compacting recycled concrete beams were smaller than that of the ordinary concrete beam.(3)The effect of load level and corrosion time on the flexural performance of self-compacting recycled concrete beams was studied by carrying out flexural tests on corroded beams.As the load level increases,the corroded self-compacting recycled concrete beams change from ductile failure to brittle failure,and the bending bearing capacity also decreases,and the stiffness and curvature ductility coefficients increase and then decrease;Under the same conditions,the ultimate bearing capacity of self-compacting recycled concrete beams is comparable to ordinary concrete beams and the stiffness is not much different,but the curvature ductility coefficient and displacement ductility coefficient are significantly higher than ordinary concrete beams.In addition,a calculation formula for the ultimate bearing capacity,stiffness and curvature ductility coefficient of the corroded self-compacting recycled concrete beam under the influence of load is proposed.