How many times the radius of action should the distance be between each internal vibrator insertion?

The correct understanding of the distance between each internal vibrator insertion revolves around ensuring effective consolidation of the material. The guideline suggesting a distance of one to one and a half times the radius of action is based on the need to overlap the area influenced by each insertion. This distance allows the vibrators to adequately affect the surrounding material, ensuring that there are no voids or weak spots once the material hardens.

This approach maximizes the effectiveness of the vibrators, as it helps guarantee a thorough and uniform compaction process, which is essential in applications like concrete placement. Ensuring that the radius of action is properly overlapped means that the entire area receiving vibrative treatment benefits from the internal vibrators, thus enhancing the quality and integrity of the final structure.

While the other options might suggest varying distances, they do not ensure the same level of thoroughness in consolidation. Distances that are too short may lead to over-compaction, while those that are too far apart might leave sections inadequately treated, resulting in potential weaknesses in the set material. Thus, the one to one and a half times the radius of action is optimal for achieving the best results in this context.