Production Operations: Forms, Casting, Consolidation, and Curing
What this domain tests
This domain tests whether the plant controls forms, placement, consolidation, and curing well enough to produce the specified geometry, cover, strength, and durability. Questions often ask what to do when a production step is outside the approved procedure.
Core rules
- Forms must be clean, sound, properly aligned, and coated with a compatible release agent. Joints and blockouts must prevent paste loss.
- Reinforcement and strand must be placed at the approved cover and spacing. Chairs, spacers, and hold-downs must not displace during casting.
- Concrete is placed in controlled lifts and consolidated without segregation. Vibrators should be inserted systematically and not used to move concrete laterally.
- Curing must preserve moisture and temperature. Steam curing needs a controlled initial delay, limited temperature rise, a maximum temperature, and a controlled cooling period; use the approved plant regime.
- Release and transfer are permitted only after the specified strength and maturity criteria are satisfied.
Worked example
A plant specifies a 3 h presteaming period, a maximum rise of 30 F per hour, and a maximum curing temperature of 140 F. Ambient concrete is 60 F. The target rise is 80 F, so at 30 F per hour the rise takes 2.7 h. Because the 3 h initial delay is longer, steam starts after 3 h and reaches 140 F at 5.7 h. The recorder shows the delay, rise rate, hold, and cooling; transfer waits for the release strength.
Traps
Starting steam before the initial delay; exceeding the maximum temperature; cooling too rapidly; using a vibrator to spread concrete; and transferring prestress on a cylinder that was not cured with the product.