[Er.Amit Mathur]

Procedure of Post Tensioning





Placing tendons

Tendons are housed in tendon ducts and the ducts are fixed in their predetermined alignment, level and profile. (Sometimes the tendons are threaded through the ducts after concreting.)
The tendon ducts shall be securely tied to the reinforcement to prevent dislodgment during concreting.

Concreting

Insitu concrete is cast. It is then cured as normal reinforced concrete.

Stressing (Tensioning)

Stressing can be carried out when the concrete has achieved sufficient strength. Stressing is performed by using a hydraulic jack.

During stressing, the readings of load and extension are recorded. When about one-half of the designed stressing load has been reached, a graph of load against extension is plotted. An extension correction is obtained from the plot by extrapolation method.
Stressing is continued until the designed load has been reached. Check if the corrected extension matches with the theoretical value. If it does, the tendon can be wedged to the anchorage. Otherwise, remedial action shall be taken.

Grouting

The ducts are grouted with cement grout through the grout holes/tubes to protect the tendons from corrosion.