Manufacturing Process
Procedure For Pole Manufacturing
All reinforcement and ducts shall be accurately placed and maintained in position during manufacturing. Grouping of high tensile wires may be permitted as long as the diameter of the wire is between 3mm and 5mm.
For post-tensioned poles, the relative position of wires in a cable, whether curved or straight, shall be accurately maintained by suitable means to ensure the free flow of gout.
For the pre-stressed pretension system, all wires shall be accurately stretched with uniform pre-stress in each wire. Each wire or group of cables shall be anchored positively during casting. Care shall be taken to see that the anchorages yield after the concrete attains the necessary strengths.
Grouting
All post-tensioned work ducts shall be grouted using any suitable grouting techniques.
Cover
In pre-tensioned work, the cover of concrete measured from the outside of the pre-stressing tendon shall be at least 30mm or the size of the cable or bar, whichever is more significant.
Spacing
In the case of a single wire used in a pre-tensioned system, the minimum precise spacing shall be less than greater of the following:
Three times the diameter of the wire
One and one-third 11/3 times the maximum size of aggregate used.
In the case of cables or large bars, the minimum precise spacing (measured between sheath/ducts, wherever used) shall not be less than greater of the following:
The high tensile steel wire or bar shall be continuous over the entire length of the tendon. Welding shall not be allowed in any case.
5mm plus the maximum size of aggregate.
The maximum size of cables or bars
Welding and lapping of reinforcement
Curing
Earthing shall be provided by having a 25×3 mm copper strip or equivalent bare copper cable.
Provide two holes of suitable dimensions 215mm from the top and 150mm below ground level to enable a 25 mm x 3 mm copper strip or equivalent bare copper cable to be taken from the top hole to the bottom through the centre hole. During manufacturing, a sufficient number of holes shall be provided in the poles to attach cross arms and other equipment.
The concrete shall be covered with a layer of shaking and canvas hessian or similar absorbent material and kept constantly wet until the strength of the concrete is equal to the minimum power of the transfer of prestress.
4 mm diameter galvanized iron wire embedded in concrete during manufacture and the ends of the strip or cable left projecting from the pole to a length of 50mm at 215 mm from the top and 150 mm below ground level.
Daily tests on concrete cubes shall be carried out during manufacturing until the concrete achieves the required strength at transfer. After that, the concrete examination shall be carried out as detailed in IS 1343. The manufacturer shall supply when required by the purchaser or his representative. If the purchaser desires, the manufacturer-supplied cubes shall be tested following IS 456.
If desired by the purchaser, to facilitate the handling of poles during transport and erection, an eyehook may be provided in every bar at 100mm below ground level on the face of the stick to utilize the maximum flexural strength of the section during handling.