For cast-in-place SFRC when is internal vibration used and when is form vibration used?

For cast-in-place SFRC when is internal vibration used and when is form vibration used?

For cast insitu, internal vibration is the most used option to consolidate the concrete. Form vibration is generally used in the precast industry.

When steel fiber concrete is cast into form work a small amount of vibration of the forms helps keep the fibers from touching the forms and thereby from being visible when the forms are removed. For example, during casting of steel fiber reinforced precast structures, the forms are vibrated to consolidate the concrete. this action results in an almost fiber free surface of the structures. So allowing a short period of form vibration in the all cast-in-place structures, in addition to internal vibration where possible, will provide the best finished surface.