Experimental Study on Quality Monitoring of Prestressed Pipeline Grouting Based on Electromechanical Impedance

In prestressed concrete structures, due to mechanical and artificial factors, the grouting of the prestressed pipeline is not dense, which seriously affects the durability and safety performance of the structure. Nondestructive monitoring of the health of the grouting of prestressed pipelines has become a key concern in the industry. This study monitored the grouting quality of prestressed pipelines using the electromechanical impedance method. One lead zirconium titanate (PZT) piezoceramic transducer with epoxy resin protective protection, called a smart aggregate, which has the advantages of low cost, high sensitivity, and wide frequency response range, was bonded on the pipeline and prestressed tendons in the pipeline. The experimental procedures simulated five stages during the grouting process, which included empty status, 25%, 50%, and 75% grouting, and full grouting of the prestressed pipeline. Trends in the conductance and susceptance spectrum curves were analyzed. Both the root-mean square deviation (RMSD) and the compactness index (CI) increased with increasing grouting compactness. The experimental results showed that the RMSD increased with increasing grouting density, and with increasing grouting density, the peak frequencies of the curves shifted in the direction of increasing frequency, and the peak values of the curves decreased. Therefore, the electromechanical impedance technique can effectively monitor the grouting quality of prestressed pipelines.