Experimental Studies On Concrete Strength Test Using PZT Impedance Method

As known to all, the strength is one of the most important indicators of concrete. To strengthen concrete quality control and testing becomes an important part of building management. However, because of the limitations of the traditional cubes compression strength test, people continue to study on situ detection of structural concrete strength under different conditions using nondestructive testing method. Meanwhile, in order to meet the current needs of the rapid construction, predicting concrete late strength with early strength also becomes an important topic in academic fields.This thesis first outlines the research of the traditional detection methods of the concrete compression strength, points out their deficiencies and the issue difficult to resolve, then introduces new methods of nondestructive testing of concrete compression strength, discusses the research progress of various methods. The basic theory of PZT impedance method for the detection of structural strength is shown followed. Finally, based on the experimental results and analysis of the concrete cubes compression strength testing during 28 days using PZT impedance method, the effectiveness of PZT impedance method applying to the concrete strength testing is verified.Test results show that: the peak of PZT electric admittance spectrum curve turns out apparent drift during 28 days period. With the growth of age, piezoelectric admittance curve gradually moves on the direction of the peak frequency increased. Compared to the changes of the compression strength of concrete cubes in experiment, they have consistency, that is, the curve grows rapid before eight days, and then relative ease after eight days. When another parameter RMSD(root mean square deviation) is used to value the admittance of the real and imaginary parts, it also shows the same trend with the strength.As a new detection method, piezoelectric impedance method is still in the development stage, and the researches are not ripe yet. The application of piezoelectric impedance method in other types of concrete and under different curing conditions needs more in-depth research in the future. In addition, the monitoring of concrete strength before the initial setting needs further study with the PZT embedded in the concrete.