Experimental Study On Mechanical Properties Of Reinforced Semi-grouting Sleeve Connection Under Freeze-thaw

With the implementation of the "Thirteenth Five-Year Plan",prefabricated concrete structures have been widely valued and applied in the modernization of the building industry.Grouting sleeve connection technology,as an important form of assembled structural connection,When assembling and connecting,the embedded steel bar is extended into the embedded sleeve,and then an effective connection is formed by pouring the grout to ensure the integrity of the assembled structure.The main research work is as follows:1.Experimental study on the optimum ratio of grouting material.Choose fixed by orthogonal experiment method,the grouting material raw material parameters of water/cement ratio,sand ratio,dosage of water reducing agent,defoaming agent dosage,considering the fly ash content,mineral content,silicon ash content three influence factors,three levels can be set respectively,get 9 groups of test plan,test grouting material fluidity,vertical expansion ratio,respectively,under the standard curing condition compressive flexural strength of the specimens,the optimum mixture ratio of grouting material is water-binder ratio of 0.28,mortar to 1,p.II52.5 common Portland cement 680.4 g,40.5 g(5%)of fly ash and mineral powder 64.8 g(8%),Silica fume 24.3g(3%),water reducer content of 0.4%,defoaming agent content of 0.2%,28 d compressive strength of 95.6MPa..2.Experimental study on mechanical properties of half-sleeve grouting joint under standard curing conditions.Considering the two influencing factors of grouting material strength and steel anchorage length,6 groups of half grouting sleeve connectors were made,3 for each group,a total of 18 pieces.Carry out vertical tensile test after standard curing.Experimental results show that 18 specimens received three failure modes,fitting compared with reinforced material limit strength,yield strength performance improvement,grouting material strength,steel bar anchoring length increases favorable influence on fitting mechanics performance,ultimate tension when fitting damage than reinforced material ultimate tension,an average of 120 k N.3.Experimental study on mechanical properties of lower half sleeve grouting joint under freeze-thaw action.Make 18 sleeve connectors of the same specification as under standard curing,conduct vertical tensile test after 30 freeze-thaw cycles at-10℃～20℃,and compare with the tensile data under standard curing.The results show that after freeze-thaw,a small amount of grouting material will fall off at the end of the specimen sleeve,and the pores of grouting material will increase.After freezing and thawing,the performance of joints such as ultimate tensile force,yield strength and bonding stress decreased,and the deformation of joints increased significantly when the joints were damaged,with the maximum deformation value reaching 60.74 mm,with an average increase of 17.2%.The strength of grouting material and the anchorage length of steel bar increase,the anchorage performance between grouting material and steel bar increases,and the deformation increment decreases.The damaged connector grade meets the requirements of class I connector in the industry specification.Protection measures should be implemented in winter construction to prevent freeze-thaw damage.