CSLB C-8 Concrete (Trade Exam) — All Questions
27 questions
Proof-rolling reveals a soft, rutting area in a slab subgrade. What should be done?
- a.Replace it with compacted fill.✓
- b.Pour thicker concrete over it.
- c.Leave it; the slab will bridge it.
- d.Cover it with plastic sheeting.
A uniform foundation matters more than a strong one, and there should be no hard or soft spots. A soft area left in place becomes a crack line; it is removed or reworked and recompacted.IMCP Manual for Concrete Pavement, 2nd ed. (FHWA/CP Tech Center, 2019)
Expansive clay under a planned slab has dried out badly during a delay. Why is that a concern?
- a.Dry clay makes the slab cure faster.
- b.Dry clay is always Type A soil.
- c.Later swelling can lift the slab.✓
- d.Dry clay has no effect on slabs.
The IMCP manual notes expansive soils cause trouble when compacted too dry or allowed to dry out before paving; later wetting makes them swell unevenly. Moisture conditioning per the soils report addresses it.IMCP Manual for Concrete Pavement, 2nd ed. (FHWA/CP Tech Center, 2019)
A dry, semi-porous subgrade will receive a footing. What does the federal guide specification say to do?
- a.Flood it to 2 inches deep.
- b.Cover it with dry cement.
- c.Leave it dry for better bond.
- d.Sprinkle it to eliminate suction.✓
The specification says to sprinkle a semi-porous, dry subgrade to eliminate suction when concrete is deposited, or seal it with the specified vapor retarder. Flooding leaves standing water, which must be removed.UFGS 03 30 00 Cast-in-Place Concrete (Chg 10, Aug 2025)
Under the 811 law, how wide is the tolerance zone around an operator's field marking?
- a.5 feet on each side
- b.12 inches on each side
- c.24 inches on each side✓
- d.36 inches total
Government Code §4216 defines the tolerance zone as 24 inches on each side of the operator's field marking; inside it, the excavator uses hand tools to find the exact location first.Cal. Gov. Code §§4216–4216.9
A footing will be dug 6 ft from a high-priority gas transmission line. What must happen first?
- a.Nothing extra; hand dig only
- b.An onsite meeting✓
- c.A Cal/OSHA permit for the line
- d.A second 811 ticket
When excavation is proposed within 10 feet of a high-priority installation, the operator sets up an onsite meeting, and the excavator may not begin until it is completed.Cal. Gov. Code §§4216–4216.9
For the 811 notice period, which of these counts as a working day?
- a.A non-holiday Wednesday✓
- b.A state holiday
- c.A Sunday afternoon
- d.A Saturday morning
A working day is a weekday, Monday through Friday, 7:00 a.m. to 5:00 p.m., excluding federal and state holidays. Weekends and holidays do not count toward the two working days.Cal. Gov. Code §§4216–4216.9
What must every operator on the ticket provide before the legal excavation start time?
- a.A copy of its insurance
- b.A crew to dig by hand
- c.A written excavation permit
- d.An electronic positive response✓
Every operator must supply an electronic positive response through the regional notification center before the legal start date and time, and the excavator may not begin until all listed operators have done so.Cal. Gov. Code §§4216–4216.9
When may an excavation have vertical sides with no protective system, whatever its depth?
- a.When it is entirely in stable rock✓
- b.When it is dug in dry clay
- c.When workers wear hard hats
- d.When it will be open one day
Title 8 §1541.1 exempts excavations made entirely in stable rock. Dry clay can still cave, and short duration or PPE does not replace a protective system.Cal. Code Regs. tit. 8, §1541.1
An 8-ft-deep excavation in Type A soil will be sloped. How far back must each side lay back from the bottom edge?
- a.8 feet
- b.12 feet
- c.6 feet✓
- d.4 feet
Type A soil is sloped no steeper than 3/4 horizontal to 1 vertical for excavations under 20 ft: 0.75 × 8 = 6 ft. Eight feet is a 1:1 Type B slope and 12 ft is the 1½:1 Type C slope.Cal. Code Regs. tit. 8, §1541.1, App. B
A 6-ft excavation is near an old landfill where hazardous gases could be present. What is required before entry?
- a.Only post a warning sign.
- b.Only limit entry to 15 minutes.
- c.Only open the trench wider.
- d.Test the atmosphere first.✓
Where oxygen deficiency (under 19.5%) or a hazardous atmosphere could reasonably exist, the atmosphere must be tested before employees enter excavations greater than 4 ft deep.Cal. Code Regs. tit. 8, §1541
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A worker must enter a deep bell-bottom pier hole. What does Title 8 require?
- a.Only a hard hat and gloves
- b.A harness with an attended lifeline✓
- c.A second worker in the hole
- d.A ladder within 50 feet
Employees entering bell-bottom pier holes must wear a harness with a lifeline, separate from any material line, individually attended at all times.Cal. Code Regs. tit. 8, §1541
Why are layout lines often carried on batter boards set back from the corners?
- a.To mark the property line.
- b.To hold the forms plumb.
- c.To make the corners square.
- d.So the lines survive excavation.✓
Stakes on the exact corners are dug out with the footing; batter boards set outside the work hold the string lines so they can be removed for digging and restored to the same marks.Field layout practice; Caltrans Reinforced Concrete Construction Manual (June 2025), ch. 2 (control stakes)
A rectangular form layout measures 36 ft and 40 ft on its two diagonals. What does that tell you?
- a.Only the sides are wrong.
- b.The slab is 38 ft long.
- c.The layout is square.
- d.The layout is not square.✓
A true rectangle has equal diagonals; unequal diagonals mean the layout is a parallelogram and a corner is out of square.Field layout practice (rectangle geometry)
What is the job of the kickers on a wall form?
- a.To bevel the top edge
- b.To hold the rebar off the form
- c.Brace it plumb to the ground✓
- d.To tie the two faces together
Kickers are diagonal braces between the form and the ground or a stable platform that keep vertical forms plumb. Ties hold the faces together and chamfers bevel edges.Caltrans Reinforced Concrete Construction Manual (June 2025), ch. 3
After a snap tie is tensioned with its wedge, what keeps the wedge from loosening during the pour?
- a.It is nailed to the form.✓
- b.It is left loose to flex.
- c.It is taped to the waler.
- d.It is welded to the tie.
Caltrans notes that once the tie is tensioned, the tie wedge is nailed to the form so it will not move and loosen during concrete placement.Caltrans Reinforced Concrete Construction Manual (June 2025), ch. 3
A wall will be poured on a cold morning. How does the low concrete temperature affect form pressure?
- a.Pressure rises only if it is air-entrained.
- b.Pressure rises, as it stays fluid longer.✓
- c.Temperature has no effect.
- d.Pressure falls, as it sets faster.
At low temperatures concrete stays fluid longer, so a greater height acts as fluid and lateral pressure is higher; forms for cold-weather pours must account for it.Caltrans Reinforced Concrete Construction Manual (June 2025), ch. 3
Form release agent is being sprayed next to yesterday's wall at a construction joint. What must it not touch?
- a.The form ties
- b.The plywood edges
- c.The hardened joint surface✓
- d.The inside of the new forms
Release agent must not contact reinforcement or hardened concrete against which fresh concrete will be placed, because it prevents bond at the joint.UFGS 03 30 00 Cast-in-Place Concrete (Chg 10, Aug 2025)
A falsework span is short and low, but a traffic lane will pass beneath it. Who must sign the design?
- a.The foreman
- b.A registered civil engineer✓
- c.The building inspector
- d.The rebar supplier
Title 8 §1717 requires calculations and drawings signed by a California registered civil engineer when provisions are made for vehicular or railroad traffic through falsework, regardless of height or span.Cal. Code Regs. tit. 8, §1717
Shoring will support a 4-inch elevated slab without carts. What minimum design load applies?
- a.70 pounds per square foot
- b.120 pounds per square foot
- c.100 pounds per square foot✓
- d.50 pounds per square foot
Concrete weight (150 × 0.333 = 50 psf) plus 20 psf is 70 psf, but the total may not be less than 100 psf, so 100 psf governs.Cal. Code Regs. tit. 8, §1717
How should vapor retarder sheets be laid out under a slab?
- a.With gaps so water can drain
- b.In the widest sheets practicable✓
- c.Only under the slab edges
- d.In narrow strips for easy handling
The federal specification calls for the greatest widths and lengths practicable to eliminate joints, with laps as specified. Gaps and strips defeat the retarder.UFGS 03 30 00 Cast-in-Place Concrete (Chg 10, Aug 2025)
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What does filter fabric around a drain rock envelope do?
- a.Adds strength to the slab
- b.Keeps fines out✓
- c.Replaces the need for pipe
- d.Makes the pipe waterproof
Filter fabric keeps fines from migrating into the drain rock and clogging it; Caltrans requires it installed per the manufacturer's instructions where drains are used.Caltrans Reinforced Concrete Construction Manual (June 2025), ch. 6
A perforated subdrain is being laid. What slope should the pipe have?
- a.A low point in the middle
- b.A continuous fall to the outlet✓
- c.An uphill run to the outlet
- d.Dead level for its whole length
A drain must carry water to its outlet, so it needs continuous fall; a level pipe or a low spot holds water instead of removing it.IMCP Manual for Concrete Pavement, 2nd ed. (FHWA/CP Tech Center, 2019)
On a Caltrans job, the plans do not state the clear cover for a formed retaining wall. What cover does Caltrans describe as typical?
- a.2 inches minimum✓
- b.3/4 inch minimum
- c.No cover is needed
- d.6 inches minimum
Caltrans states clear cover is typically 2 inches minimum unless specified otherwise, with more for cast-in-drilled-hole piles (3 in) and severe environments. Three-quarters of an inch is an interior-slab value in other specifications.Caltrans Reinforced Concrete Construction Manual (June 2025), ch. 4
On a Caltrans job, which bar supports are generally not allowed?
- a.Ferrous metal chairs
- b.Precast mortar blocks
- c.Wood, plastic or aluminum✓
- d.Dobies with tie wire
Caltrans' specification does not allow aluminum, plastic or wood spacers and supports (with a CIDH exception); precast mortar blocks (dobies) and ferrous metal chairs are acceptable.Caltrans Reinforced Concrete Construction Manual (June 2025), ch. 4
What tie wire do ironworkers usually use to fasten rebar intersections?
- a.Welding rod
- b.About 22 gauge
- c.About 8 gauge
- d.About 16.5 gauge✓
Caltrans notes ironworkers usually use 16.5-gauge tie wire at intersections; enough intersections are tied to keep the steel stable, and crossing bars are not tack welded.Caltrans Reinforced Concrete Construction Manual (June 2025), ch. 4
Two bars are lap-spliced in a wall. How must the lapped bars be placed?
- a.Bent at 90 degrees
- b.Welded end to end
- c.Spaced 6 inches apart
- d.In contact and tied✓
Caltrans states lapped sections must be in contact and securely tied, with at least 2 inches clear to adjacent reinforcement or splices.Caltrans Reinforced Concrete Construction Manual (June 2025), ch. 4
A pipe sleeve passes through a slab form. What does the federal specification say about the sleeve before the pour?
- a.Leave it open for air to escape.
- b.Fill it with removable material.✓
- c.Cut it off after the pour.
- d.Fill it with grout.
The specification says to temporarily fill voids in sleeves with readily removable material to keep concrete out, and to secure the sleeve against displacement.UFGS 03 30 00 Cast-in-Place Concrete (Chg 10, Aug 2025)