CSLB C-8 Concrete (Trade Exam) — All Questions
7 questions
Wall forms that needed finishing were stripped early. What must follow right away?
- a.Curing the exposed faces✓
- b.A coat of form oil
- c.Nothing until day 7
- d.Sandblasting of the wall
If forms are removed before the end of the curing period, curing and protection must be provided for the rest of it; form oil is not a curing method.UFGS 03 30 00 Cast-in-Place Concrete (Chg 10, Aug 2025)
How stiff should dry-pack mortar be?
- a.Pourable like grout
- b.Completely dry powder
- c.Stiff; balls when squeezed✓
- d.Wet enough to self-level
Dry pack is mixed with just enough water to form a ball when squeezed gently by hand, then rammed into place; wetter mixes shrink and bond poorly.Caltrans Reinforced Concrete Construction Manual (June 2025), ch. 5
A patch on a visible gray wall looks darker than the wall. How is color usually matched?
- a.Add some white cement✓
- b.Use form oil on the patch.
- c.Paint the patch gray.
- d.Add extra water to lighten it.
Caltrans notes color matching can be achieved by adding a small amount of white cement, testing sample patches in inconspicuous locations. Extra water weakens the patch.Caltrans Reinforced Concrete Construction Manual (June 2025), ch. 5
Small surface holes appear on a wall cast against steel forms. What most likely caused them?
- a.Too much reinforcing steel
- b.Trapped air bubbles✓
- c.Late sawing of joints
- d.Excess curing compound
Bug holes come from air bubbles trapped against forms, especially impervious forms such as steel or plastic liners; proper vibration or revibration helps prevent them.Caltrans Reinforced Concrete Construction Manual (June 2025), ch. 5
How is epoxy injection of a dormant crack done?
- a.Pour epoxy into the open crack
- b.Seal it, then inject via ports✓
- c.Rout it and fill with sealant
- d.Spray epoxy over the whole wall
NPS describes sealing the crack surface on both sides and injecting epoxy through small holes or ports; routing and sealing is the method for moving cracks.National Park Service Preservation Brief 15
What must an owner know before a clear penetrating sealer is applied?
- a.It fills cracks permanently.
- b.It can't be removed once applied.✓
- c.It lasts the life of the slab.
- d.It forms a peelable film.
NPS notes penetrating sealers cannot be effectively removed (irreversible), do not bridge or fill cracks, and require periodic reapplication.National Park Service Preservation Brief 15
Why must joint sealants be inspected and replaced over time?
- a.They are only temporary fillers.
- b.They turn into mortar.
- c.They harden the concrete edges.
- d.They wear out before concrete.✓
NPS notes sealants deteriorate faster than their substrates and must be replaced periodically as part of cyclical maintenance.National Park Service Preservation Brief 15