Experimental Study And Engineering Application Of Mechanical Properties Of Semi-grouting Sleeve At Low Temperature

In recent years,the application of prefabricated concrete structure in the construction field of our country is increasing day by day,of which the "sleeve grouting connection technology" is the key link,and the performance of the joint has a profound impact on the overall quality of the building.At present,there are still some problems such as unreasonable sleeve structure,grouting defects and selection of low-temperature grouting materials.Various defects and improper material selection of connection joints will lead to a significant reduction in the bearing capacity and deformation resistance capacity of the connection joints,which will greatly increase the risk of damage of fabricated structures.The purpose of this paper is to study the construction technology of grouting sleeve under the condition of low temperature in winter,and to solve the difficulties and problems in the assembly construction in winter.On the basis of extensive investigation,this paper has carried out an experimental study on the one-way tensile strength of the semi grouted steel sleeve joint.In the experiment,the mechanical properties,ultimate bearing capacity and failure mode of the components are observed,and theoretical analysis and calculation are carried out.The results show that the ultimate tensile capacity and strength of the semi grouted steel sleeve joint cured at room temperature are better than those at low temperature,and the steel bars are pulled The fracture location is 5-8cm from the grouting end or threaded end,and most of the grouting ends of the test pieces show different degrees of cone-shaped failure and fall off;with the increase of the reinforcement section size,the ultimate tensile bearing capacity of the joint gradually increases,but there is no significant impact on the ultimate tensile strength of the joint.When the temperature of half sleeve grouting construction area is lower than-5? in winter,heat storage maintenance shall be carried out in time.The temperature of grouting and maintenance stage is suggested to be above 5?,the content of silica fume in grouting material shall be controlled at 3%,and the content of calcium formate shall be controlled at 2%,which can improve the work ability and strength of grouting material.Increasing the number of sleeve ring ribs and the height of the inner wall bulge can improve the bearing capacity of the grouting connection of the steel sleeve,and the welding ribs will produce greater mechanical bite force and friction force,thus enhancing the bearing capacity of the sleeve.