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This short clip shows how to apply paint-marks prior to stressing of post-tension tendons. It’s recommended to use a straight-edge, metal to help with elongation measurements. Refer to the Post-Tensioning Institute’s “Field Procedures Manual for Unbonded Single-Strand Tendons” Chapter 7 for additional information. Copyright © 2011 by AMSYSCO, Inc. All rights reserved.
As a post-tensioning inspector or installer, have you ever been in a situation whether you are unsure whether some PT tendons have been stressed? By not having a PT tendon stressed, this could have detrimental effects on the structure. Here are three pointers that may help you out: 1. PAINT-MARKS : Compare the location of the paint-marks to other tendons of the same length. If you see a major difference in one or more paint-marks, then the flag should go up. If the location of the paint marks are similar, then either ALL of tendon have been stressed or NONE of them have been stressed. If you have a deviation, then you may have an unstressed tendons or an elongation issue. (Related Video : Applying paint mark for post-tensioning tendon). 2. BITE-MARKS : Check whether there are “bite-marks” on the tendons. During the stressing operation, the hydraulic jack “grabs” the stressing tail of the PT strand and and creates a series of small bite-marks. The picture below shows two tendons that have been stressed (click picture to enlarge). This visual inspection helps if your paint-marks have been washed away.  Bitemarks into Post-Tensioning Strand 3. ELONGATION RECORDING : AMSYSCO highly recommends that the inspector (or testing agency) record elongation during the stressing operations…rather than several hours later. This step increases the quality control of the project and eliminates a potential unstressed tendon. - Neel Khosa, Vice President, AMSYSCO _________________________________________________ Copyright © 2011 by AMSYSCO, Inc. All rights reserved.
With some post-tension systems, the installer is required to strip the plastic-sheathing in order to install the intermediate anchors at the construction joints. One issue is how to protect the exposed strand until the second pour is made (pictured below – Pour #1 on left and Pour #2 on right).  Exposed strand at construction joint One solution is to put visqueen or a tarp on top of the bulkhead until the second pour is made. This has been specified by some Structural Engineers in order to protect the exposed strand from corrosive elements such as rain and snow. Another solution is to push the plastic tubes on to the backside of the bulkhead in the second pour (pictured below). This would provide added protection to the post-tension system at a lower cost than tarpping.  Strand protected by Tubing - Neel Khosa, Vice President _________________________________________________ Copyright © 2011 by AMSYSCO, Inc. All rights reserved.
Occassionally, the field will encounter a condition where the post-tensioned beam’s CGS (center of gravity of steel) requires several PT beams be installed in the slab. In other words, some PT anchors will not be installed within the web of the beam, but in the flange of the beam. Below are several pictures showing how these tendons can be installed at the jobsite.  Beam tendons sweeping out of beam  Beam tendons swept into slab  Beam tendons swept into slab at Anchors
It is recommended to add some #3 hairpins where the tendons curve to prevent blowouts in the concrete. Without hairpins, the tendon may “slice” through the concrete during the stressing operations. The tendon has a natural tendency to straighten out during the stressing operations. - Neel Khosa, Vice President _________________________________________________ Copyright © 2011 by AMSYSCO, Inc. All rights reserved.
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