EVALUATION OF MORTAR-GROUTING EFFICIENCY BETWEEN PRECAST CONCRETE TRACK LAYERS BY CONTINUOUS RESONANCE TESTS

초록

In this research, the continuous resonance method was employed to evaluate the lateral variation in mortar-filling quality of precast concrete track. In the continuous resonance method, the amplitude of frequency response is measured using an instrumented hammer and an accelerometer is plotted against a pseudo-depth, which is half of the wave velocity divided by the frequency. The frequency response functions were measured at consecutive locations of measurement with 6-cm intervals, and combined together to generate a 2-D plot of frequency response. The sections with strong reflections or large amplitude of frequency response were found to be areas with high possibilities of internal voids and unfilled areas. The 2-D frequency response plot was efficient in locating possible areas of defect.