Research on the Sleeve Grouting Fullness Testing of Prefabricated Structures Based on Piezoelectric Method

Abstract

The traditional methods for testing the sleeve grouting fullness of prefabricated structures generally face the technical challenges such as high detection cost and inability to detect in real-time. In order to solve these technical challenges, the detection method and instrument based on the piezoelectric testing principle were developed. Through the electrical properties tests of grouting materials and grouting-leakage cycle tests of transparent sleeves, the effectiveness of the piezoelectric method for testing grout leakage defects was analyzed. The research results indicate that measuring the voltage changes before and after the piezoelectric sensor is wrapped in the grouting slurry can effectively evaluate the sleeve grouting fullness. The voltage measured by the piezoelectric sensor is significantly reduced after the sensor is wrapped in the grouting material (full grouting). Then the voltage increases after grouting leakage (insufficient grouting), and decreases again after supplementary grouting (full grouting). Moreover, whether the piezoelectric sensor is placed horizontally or vertically, the voltage shows obvious changes, indicating that the piezoelectric method is less affected by the sensor laying mode. Considering that the vertical embedding method is more stable for piezoelectric data, it is recommended to use the vertical laying mode in engineering projects. Furthermore, through the prefabricated model tests, the threshold for judging grouting fullness using piezoelectric method was determined. The test results show that the threshold for determining the grouting fullness using piezoelectric method can be set to 0.40. That is to say, when the voltage value is less than 0.40, it can be determined as complete grouting, otherwise it can be determined as insufficient grouting. The case studies results indicate that the piezoelectric method meets the quality control requirements during the grouting process of prefabricated structural sleeves. The research results provide a new approach and practical reference for solving the quality detection problem of sleeve grouting.