Why Engineers Tension Cables Inside Concrete 😮 #shorts

Added: 2026-05-22

[00:00:00]These cables are not just placed inside the concrete. They will be pulled after hardening. That is the principle of post-tensioned pre-stressing. First, the ducts are positioned inside the reinforcement. Then, the strands are passed through them. The concrete is poured, it hardens, and then a hydraulic jack tensions the cables from the end.

[00:00:20]By pulling the cables, the element is compressed in advance before the loads even arrive. Result? Less cracking, longer spans, and a more efficient structure. But here's a side question.

[00:00:31]In your opinion, which step is the most critical? The positioning of the ducts, the tensioning operation, or the grout injection?