Study On Performance And Application Of Fiber Reinforced Wet Joint Concrete

As a new construction technology,prefabricated concrete structure is characterized by high production efficiency and guaranteed component quality,so it is favored by the construction industry and construction industry.However,the connection between prefabricated members of prefabricated concrete structure is not only the weak link of the structure,but also the premise and foundation to ensure the overall seismic performance of the structure.At the same time,in the large-scale assembly of precast concrete components,the connection and treatment of joints are often the key links affecting the progress of the project and the overall quality,which requires that the wet joint concrete can realize the collaborative work with the prefabricated components in a short time.In this paper,based on the excellent mechanical properties and bonding properties of steel fiber reinforced self compacting concrete,and considering the working performance,volume stability of wet joint concrete and the comprehensive requirements of new and old concrete working together,a new fiber-reinforced wet joint concrete with vibration free(self compacting),early strength and no shrinkage is proposed.And it is applied to prefabricated integral frame joints of precast columns and composite beams,and the seismic performance of post poured frame joints is analyzed through nonlinear finite element numerical simulation.In this paper,the workability,shrinkage,basic mechanical properties of wet joint concrete and seismic simulation analysis of frame joints are studied(1)The type and content of steel fiber have great influence on the fluidity of concrete,and the value of slump expansion decreases with the increase of steel fiber volume content.When the volume content of milled and shear steel fiber is the same,the slump expansion of milled steel fiber reinforced concrete is larger.Through the working performance test,it is finally determined that the steel fiber type is milling type,and when the volume content is 0.8%,the concrete can meet the requirements of SF2 self compacting grade.Through the j-ring expansion test,the wet joint concrete can meet the requirements of pa2 gap trafficability.(2)Through the basic mechanical properties test of ordinary concrete,self compacting concrete without steel fiber and steel fiber self compacting concrete(wet joint concrete),it is found that the splitting tensile strength and flexural strength of self compacting concrete increase by 25.3% and 32% respectively,but the influence on the compressive strength and elastic modulus of concrete is small.The splitting tensile strength of new and old concrete composite specimens with roughened interface is about 10% less than that of dentate interface.(3)Comparing the shrinkage test of steel fiber reinforced self compacting concrete(wet joint concrete)and ordinary concrete,it is found that the early shrinkage rate of the two kinds of concrete increases rapidly,and gradually slows down in the later stage.The shrinkage of steel fiber reinforced self compacting concrete is 27.2% less than that of ordinary concrete at 28 days.(4)The results show that the stiffness degradation,ductility coefficient and energy dissipation capacity of the prefabricated frame post cast joint are better than those of the cast-in-place joint under the axial compression ratio of 0.3 and 0.5,which indicates that the prefabricated frame post cast joint can well meet the seismic requirements.