A NEW METHOD FOR MEASURING IN-SITU CONCRETE ELASTIC-CONSTANTS USING HORIZONTALLY POLARIZED CONICAL TRANSDUCERS

This paper presents a result on the measurements of longitudinal and R ayleigh wave velocities in a concrete plate using horizontally polariz ed conical transducers. The characteristics of horizontally polarized surface responses due to a point source applied at a half-space and a plate are analyzed and discussed. The analyses show that the horizonta l component of a skimming longitudinal wavefront due to a point source is much larger than its vertical component. This suggests the utiliza tion of a horizontal component of a surface response to detect the ski mming longitudinal wavefront. In addition, theoretical analysis shows that by using the horizontal component to determine the Rayleigh wave velocity, the source-to-receiver distance can be reduced significantly . Homemade horizontally polarized conical transducers were fabricated to demonstrate the feasibility of the present method on measuring the dynamic concrete elastic constants. Experimental results on the measur ements of the horizontal component of a surface response due to a poin t impact were in good agreement with the theoretical prediction. In co nclusion, it is noted that, based on this proposed method, concrete dy namic elastic constants can be determined through a single transient e lastic wave experiment. (C) 1997 Acoustical Society of America.