Research On Sleeve Grouting Fullness Testing Technology Based On The Outlet Impact Method

Sleeve grouting connections for reinforcement are the most widely used connection method for assembled concrete structures.In practical projects,sleeve grouting defects are the most common problem,which can affect the overall mechanical properties of the structure.At present,qualitative detection methods such as the pre-buried wire drawing method and the pre-buried sensor method have disadvantages such as high cost and low accuracy,while quantitative detection methods such as the borehole endoscopy method and the X-ray method have their own limitations in terms of convenience and conditions of use,although the detection results are more accurate.The existence of an accurate and efficient qualitative testing method would greatly improve the efficiency of the test by first quickly checking the grout fullness of the sleeve to determine if the sleeve is full,and then quantitatively testing the sleeve if it fails the grout fullness test.Therefore,this paper proposes a new rapid method for detecting the grout fullness of reinforcement sleeves,the main research content and results are as follows.(1)Analyse the types of sleeve grouting defects and their causes,based on the defects at the top of the sleeve,the basic principle of the outlet impact method is studied,and the operating steps and requirements of the outlet impact method are determined;explore the operation mode of the testing apparatus,and develop the testing apparatus for the outlet impact method such as impact force hammer and T-connector;conduct sensitivity calibration tests on the piezoelectric force sensor,and the test results show that: the sensitivity is 0.504mv/N.(2)According to the actual engineering situation,the grout length,PVC pipe diameter,grout brand and age were selected as the influencing factors of the grout outlet impact method,different levels of influencing factors were set,and test specimens were made and tested for impact release.The results of the study showed that the grout length in the outlet orifice was the most sensitive,the PVC pipe diameter was the second most sensitive,and the grout brand and age sensitivity were both insensitive.Finally,by studying the variation law of the influencing factors on the representative values,the magnitude of the representa tive values under other working conditions is explored and provided as a reference for subsequent tests.(3)Combining the actual engineering situation and the influencing factors of the slurry outlet impact method,the test scheme is designed and concrete test blocks are made,and the pressure test machine is used to simulate the pressure of 2,4 and 6storeys respectively,and the impact release test is carried out and the representative values are derived through mathematical analysis;through the above study of the law of variation of the influencing factors,the magnitude of the representative values for other working conditions is sought;in order to ensure the safety of the test results in the actual engineering In order to ensure the safety of the test results in the actual project,a safety factor of 1.4 is proposed,which in turn leads to a threshold value as a test index for the slurry outlet impact method.The results of the study show that the threshold value is 5.5k N when the number of floors is 2 and below,and 7k N when the number of floors is 2 to 6.(4)An assembled concrete structure construction site was selected and ten members were selected from the floors tested to carry out reinforcement sleeve grouting quality testing using the outlet impact method,while the borehole endoscopy method was used to verify the test results and to propose handling measures related to sleeve grouting connections after testing.The results of the study show that the results of the socket grout fullness testing by the outlet impact method are in full agreement with those of the borehole endoscopy method,and are easy to operate,efficient and cost effective.