Abstract
It is easily imagined that there might exsist some effects of reflected wave from formwork on vibratory compaction of concrete. However detailed and reliable evidences of the effects have not been reported. In the present paper, analytical and described. In the analysis, we obtained resultant acceleration of direct and reflected waves based on the function for the wave spreading in the concrete from an internal vibrator. Illustrations of the calculated results showed that when the formwork consisted of flat plates, the effect would be less than that when it was cylindrical. The measurement of acceleration amplitude for the flat plate formwork implied the interference between direct and reflected waves near the plate. Concerning the materials of formwork, steel had naturally more effect on the reflection of the vibration than wood, and unexpectedly, lining of vibration proof hard rubber showed an intermediate effect between stell and wood, which might possibly be attributed to the hardness and smoothness of the surface.
