Study On Bending Test Of C30 Recycled Coarse Aggregate Self-compacting Concrete Simple Supported Beam After Freeze-thaw Cycle

With the improvement of the urban system,the excellent ecological environment,the implementation of the strategy of rural revitalization,driving the development of all walks of life at the same time also produces more and more construction waste and industrial waste,has become a stumbling block to the construction of ecological civilization.In order to reduce the damage to the environment from solid waste such as construction waste and other industrial waste,the application of recycled self-compacting concrete materials is born.However,the durability disease has a great influence on the service life and use state of concrete building structure,so whether it is for ordinary concrete or recycled concrete,the durability problem is the problem that must be discussed in its application and popularization.Statistics show that the antifreeze performance,as an important evaluation standard for concrete durability,has also been a hot topic for scholars at home and abroad,and the existing research on the frost resistance of recycled concrete is basically focused on the mechanism of freezing and thawing and the basic mechanical properties,and less on the freeze-thaw deterioration of recycled concrete members.Therefore,in this paper,the freezing and thawing properties of regenerated coarse aggregate self-compacting concrete are studied,and the effects of 5 groups of different recycled coarse aggregate substitution rate and finite freezing and thawing on regenerated self-compacting concrete are compared and analyzed,and the better replacement rate of antifreeze regenerated self-compacting concrete is obtained.In this paper,the bending performance of the positive section after freezing and thawing cycle of 3 groups of regenerated self-compacting concrete beams is studied,which provides some reference for the study and popularization of the freeze-thaw deterioration of regenerated self-compacting concrete.The test results show that the mass loss rate and intensity loss rate of 5 groups of regenerated coarse aggregate self-compacting concrete specimens with different substitutionrates are basically increasing with the increase of the number of freeze-thaw cycles,and the relative dynamic elastic modulus shows a decreasing trend.Under certain freeze-thaw cycle times,With the increase of the replacement rate of recycled coarse aggregate,the quality loss rate and intensity loss rate of the specimen showed an increasing trend,and the relative dynamic elastic modulus decreased.When the replacement rate of recycled coarse aggregate was 50%,the antifreeze and thawing properties of concrete specimens and the utilization rate of recycled coarse aggregate were better,which could be used as the replacement rate of recycled coarse aggregate.With the increase of the number of freeze-thaw cycles,the cracking bending moment,ultimate bending moment and short-term stiffness of the beam members are decreasing after bending.The cracking bending moment and short-term stiffness of regenerated coarse aggregate self-compacting concrete bending after freezing and thawing of self-compacting concrete are less applicable to the existing formulas.