Bonded Bar Post-Tensioning System

Installation

DYWIDAG-Systems International offers a full line of special installation accessories to facilitate field assembly and installation. Inexperienced workers are easily trained in the assembly due to all threaded components. On the other hand, tendons can be delivered to the job site prefabricated when desired.

Pocket Former

The pocket former was developed as a principal accessory to provide just enough space in a block-out to position the ram onto the anchorage.

Stressing

The small, light and conveniently operated DYWIDAG Bar Jacks facilitate the stressing operation. Heavy lifting aids are generally not necessary. The jack is pushed over a pulling coupler that is threaded onto the bar protrusion behind the anchor nut. The jack is then fixed with a pulling nut.

The tension load is hydraulically transferred. The anchor nut is tightened by an internal wrench.


Stressing Notes

Straight tendons are generally stressed from one end only. In order to reduce friction losses (especially in draped tendons), it is recommended to stress from both sides.

  • bar protrusion at the anchorage before and after stressing to evaluate the effective elongation
  • counter control for elongation during stressing operation
  • gauge control for hydraulic pressure
  • to accurately comply with exceptionally high demands
  • for example, on very short tendons, special accessories can be introduced to minimize seating loss

 

 

Grouting

The durability of Post-Tensioned construction depends to a great degree on the success of the grouting operation. The hardened cement grout provides a bond between concrete and tensile element as well as primary long-term corrosion protection (alkaline medium) for the prestressing steel.
DYWIDAG developed a grouting operation that is based on thixotropic, highly plasticized grout and utilizes durable grouting equipment. Advanced methods such as pressure grouting, post-grouting and vacuum grouting all are the results of many years of development.
The grout is injected from the lower end of the anchorage or a low point of the tendon. Grouting is always done from a low-point of the tendon. This can be one of the anchorages where a grout cap with grout hose is the port for the grout. Alternatively, grouting can be done along the tendon, utilizing an intermediate grout saddle. All grouting components are threaded for easy, fast and positive connection.


Grout Cap

The grout cap is threaded on the anchor forcing the grout through grout channels in the anchor nut (slotted anchor nut) into the tendon.

Temporary Corrosion Protection - RUST BAN

A special emulsified oil (Rust Ban) provides an optimal temporary corrosion protection. The bar can be coated before shipping or as it arrives on the job site, before it is inserted into the duct. There are means to even apply the oil after the bar is installed in the sheathing. Please inquire about other corrosion protection systems to suit special requirements.


Protection against dirt and water

Special accessories were developed to properly seal accessible anchorages against the environment. This is used for tendons that remain ungrouted over a long period of time or on winter-job sites to avoid the development of ice in the tendon.