Effect of impact source on detection quality in impact echo testing of sleeve grouting

The quality of grouting is important for the mechanical performance of prefabricated buildings. The impact echo method is used to study the internal condition of grouting sleeves. Mode analysis of the sleeves is carried out by finite element methods. Impact loads with durations of 12 μs, 20 μs and 40 μs were applied to the model for impact echo studies, and the echo signals were compared by FFT transformation and wavelet transform. In impact echo experiments, steel balls with different diameters were used to impact the grouting sleeve. It was found that the characteristic frequency polarization of the echo signal with a diameter of 5 mm was the most pronounced. The research shows that for smallsized inspected objects such as grouting sleeves, the object’s own vibration frequency has a major influence on the detection result.