Abstract： There us bi effective method to test voids in post-tensioning ducts. As a new elastic wave method, impact-echo method (IEM) to evaluate grouting fullness. Through studying influencing factors on impact-echo characteristic frequency in a box girder, such as, thickness of flat, depth of duct, d/T, influencing area of duct, grouting strength and fullness, the laws of the characteristic frequency in the box girder were studied, and the judgment rules of voids was obtained. On the base of experimental data, an empirical formula calculating the characteristic frequency of a concrete deck with voids in its duct was deduced, and the value of the coefficient μ was given. Last, 8 test areas were studied, and the color pictures were given according to the characteristic frequency of each test area. The position of the ducts and the grouting fullness could be known from the pictures. Ome of these test areas was judged to have voids in its ducts. Then its ducts were chiseled out, and the result was verified. The photos of the voids were given. IEM was proved to be an effective method to evaluate grouting fullness in post-tensioning ducts.
2010, Vol. 29 
