Bar Post-Tensioning System - Stressing and Grouting
DYWIDAG Threadbars are stressed using compact lightweight hydraulic jacks. In most cases handled by one man, the jack fits over a pull rod designed to thread over the THREADBAR® protruding from the anchor nut. The jack nose contains a socket wrench and ratchet device which allow the nut to be tightened as the THREADBAR® elongates. 1-3/4 and 2-1/2 bars utilize specially equipped center-hole stressing jacks. The magnitude of the prestressing force applied is monitored by reading the hydraulic gauge pressure and by measuring the THREADBAR® elongation. The elongation can be measured directly by noting the change in THREADBAR® protusion.
| Jack Capacity | Kips | 67 | 160 | 220 | 330* | 630* |
|---|---|---|---|---|---|---|
| 1 | kN | 267 | 712 | 979 | 1,500 | 2,800 |
| 1 Bar size | in | 58 | 1, 1-1/4 | 1-1/4, 1-3/8 | 1-3/4 | 2-1/2 |
| 1 | mm | 15 | 26, 32 | 32, 36 | 46 | 66 |
| 1a** | in | 7-3/4 | 8-1/2 | 11 | N/A | N/A |
| 1 | mm | 197 | 216 | 279 | ||
| 1b | in | 3-1/4 | 4 | 6 | 6 | 7 |
| 1 | mm | 83 | 102 | 152 | 145 | 180 |
| 1 in. c | in | 24 | 26 | 30 | 36 | 43 |
| 1 | mm | 610 | 660 | 762 | 900 | 1,070 |
| 1 Weight | lbs | 50 | 80 | 110 | 334* | 500 |
| 1 | Kg | 23 | 36 | 50 | 152 | 227 |
*) This system should have a mechanical means of lifting and moving.
**) Special nose extensions for deep stressing pockets are available on request.
Note: Detailed operating and safety instructions are provided with all stressing and grouting units. Read and understand these instructions before operating equipment.
Grouting
Grouting completes the installation process for post-tensioned concrete construction.The grout is important in protecting the steel from corrosion and contributes significantly to the ultimate strength of the structure. After mixing, the grout is injected into a low point vent until consistent material is exhausted at the terminating or anchorage vent. An admixture may be used to control expansion and pumpability.