Ironworker Red Seal pre-stressing and post-tensioning practice questions.

Five free practice questions on pre-stressing and post-tensioning: block D of the Ironworker (Generalist) Red Seal exam, 10 of its 120 questions. The same work is block D of the Reinforcing exam (14 of its 120 questions). The Structural/Ornamental exam does not include it. Each question is labelled with the exams it belongs to. They are in the exam's format: four options, one correct answer. Answer each one before opening the explanation. No account, no email.

01The questions

1. Recall · Places tendons and accessories · Generalist and Reinforcing exams

   How is a seven-wire prestressing strand made up?

   1. Seven wires twisted together around a fibre core.
   2. Seven straight wires bundled side by side with no twist.
   3. Six wires laid around a three-wire centre strand.
   4. Six wires wound around a straight centre wire.
   Show the answer

   D. Correct. Seven-wire strand has six outer wires laid helically around a single straight centre wire, called the king wire. Low-relaxation seven-wire strand is the standard prestressing steel for monostrand and multistrand tendons.

   Why not the others

   A. A fibre core belongs to some wire ropes, not prestressing strand. Seven-wire strand is all steel: six wires wound around one straight centre (king) wire.

   B. Parallel wires with no lay would not hold together as a strand. In seven-wire strand, six outer wires are wound helically around a straight centre (king) wire.

   C. There is no three-wire centre. The seventh wire is a single straight centre (king) wire, with six wires wound around it.

2. Recall · Installs bursting steel and anchorages · Generalist and Reinforcing exams

   Why is a pocket former fitted between a live-end anchor and the edge form?

   1. To hold the wedges in the anchor until the tendon is stressed.
   2. To space the bursting steel back from the anchor.
   3. To leave a recess for the jack and the cut strand end.
   4. To carry the stressing force into the edge form.
   Show the answer

   C. Correct. The pocket former forms a temporary recess at the slab edge. It gives the jack access to the anchor and lets the strand tail be finished inside the face of the slab instead of at its surface.

   Why not the others

   A. Wedges at a live end are fitted at stressing, when the jack is put on. The pocket former's job is to leave a recess in the slab edge for the jack and the cut strand end.

   B. Bursting steel is placed and tied to the detail. The pocket former leaves a recess in the slab edge so the jack can reach the anchor and the cut strand end finishes inside the slab face.

   D. The edge form is stripped before stressing and carries no stressing force. The pocket former leaves the recess that gives the jack access to the anchor.

3. Procedural · Cuts and caps tendons · Generalist and Reinforcing exams

   Stressing of all the tendons on a podium slab is finished and the elongations have been recorded. When may the crew cut the strand tails?

   1. Once the stressing records are accepted.
   2. Once the stressing pockets are grouted.
   3. Right after the last tendon is stressed.
   4. As soon as each tendon's wedges seat.
   Show the answer

   A. Correct. The tails are left long until the stressing records (gauge pressures and elongations) have been reviewed and accepted, so any tendon needing re-stressing or a lift-off test can still be gripped by the jack. Then cut, cap and grout the pocket.

   Why not the others

   B. The pocket is grouted last: the tail is cut first, then capped, then the pocket is grouted. Cutting waits only for the stressing records to be accepted.

   C. Finishing the stressing does not mean the results are acceptable. If any record is out, that tendon may need the jack again, which needs the tail; cut only once the records are accepted.

   D. Cutting right after seating removes the tail the jack needs to grip if a tendon has to be re-stressed or lift-off tested. Tails are cut only once the stressing records are accepted.

4. Recall · Tensions tendons · Generalist and Reinforcing exams

   As the jack releases, the wedges are drawn a few millimetres into the anchor before they lock on the strand. What is this movement called?

   1. Elongation.
   2. Anchor set.
   3. Lift-off.
   4. Relaxation.
   Show the answer

   B. Correct. Anchor set is the movement of the wedges into the anchor as the force transfers from the jack. The force lost through it is the seating loss, which the engineer allows for; its value comes from the system's data.

   Why not the others

   A. Elongation is the stretch of the strand measured during stressing to check the force. The movement of the wedges into the anchor on release is the anchor set.

   C. Lift-off is re-jacking a tendon until the wedges just move off their seat, to find the force in it. The wedges drawing into the anchor on release is the anchor set.

   D. Relaxation is the slow loss of stress in strand held at a fixed length over time. The quick movement of the wedges into the anchor on release is the anchor set.

5. Procedural · Installs grout · Generalist and Reinforcing exams

   During grouting of a bonded tendon, grout starts to come out of the first vent downstream of the inlet. When is that vent closed?

   1. When the grout coming out is free of air and water.
   2. As soon as any grout appears at the vent.
   3. After a set volume of grout has passed the vent.
   4. Once grout shows at every vent, closing all of them together.
   Show the answer

   A. Correct. Each outlet is closed in turn, in the direction of flow, once the grout coming out runs steady and free of air and water, so no voids or water pockets are left behind.

   Why not the others

   B. The first grout to reach a vent is mixed with air and water pushed ahead of the front. The vent stays open until grout free of air and water runs from it.

   C. A volume does not show whether the air and water have cleared. The vent is closed when the grout leaving it is free of air and water.

   D. Leaving earlier vents open lets grout and pressure escape behind the front. Each vent is closed in turn as it runs with grout free of air and water.

02Answer key

03What block D covers

Post-tensioned and pre-stressed concrete: laying out the tendon profile, placing tendons and their supports, installing bursting steel and anchorages, connecting tendons to anchorages, protecting exposed tendons and damaged sheathing, setting up, running and removing the stressing equipment, cutting and capping the tails, de-stressing tendons, and setting up the grouting equipment and grouting bonded tendons.

The Red Seal Occupational Standard for Ironworker (Generalist) names this block “Performs pre-stressing/post-tensioning”. On the Generalist exam it carries 8.3% of the questions, 10 of the 120, split across three tasks. The share column is each task's weight within the block, as the Generalist standard publishes it; the other columns are the questions each exam gives the task, from each exam's information page (a dot means the task is not on that exam; Structural/Ornamental numbers its tasks as shown in brackets).

04What the questions turn on

Gauge pressure sets the force

A tendon is stressed to the gauge pressure the calibration chart gives for its specified force, and the measured elongation is then checked against the calculated value. The wedges pull a few millimetres into the anchor as the jack releases: that is the anchor set.

Tails wait for the records

Strand tails are left long until the stressing records are reviewed and accepted, so the jack can still grip any tendon that needs re-stressing or a lift-off check. Then the tails are cut, capped and the pocket filled.

Repair sheathing in layers

Where sheathing is torn and coating wiped off the strand, the coating is restored first, split tubing goes over the damage, and waterproof tape is wound past both ends of it.

Grout gives bond and protection

Set grout bonds a bonded tendon to the concrete and protects the steel from corrosion. While grouting, each vent is closed in turn, in the direction of flow, once the grout coming out runs free of air and water.

05The other blocks

The Generalist exam has six blocks, and the Structural/Ornamental and Reinforcing exams are built from four of them each. Every block has its own page of free questions:

The Ironworker Red Seal practice exam page describes the full question bank. How these questions are written and checked: how our questions are made. Found a mistake? Tell us and we will fix it.