CSLB C-8 Concrete (Trade Exam) — All Questions
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250 questions
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)
Concrete must drop 12 ft into a column form on a Caltrans-type job. What is needed?
- a.Nothing; 12 ft is allowed
- b.A drop chute✓
- c.A wetter mix so it flows
- d.A bucket dumped all at once
Caltrans limits free fall to 8 ft and says to minimize it; drop chutes control the height of fall and reduce segregation. A wetter mix weakens the concrete.Caltrans Reinforced Concrete Construction Manual (June 2025), ch. 5
Where should placement begin on a large slab-on-ground?
- a.Wherever the truck parks
- b.At several spots at once
- c.Perimeter, at one end✓
- d.In the center, working out
Caltrans describes starting along the perimeter at one end, with each batch discharged against previously placed concrete, which avoids pushing stone ahead of the mortar.Caltrans Reinforced Concrete Construction Manual (June 2025), ch. 5
How thick should lifts be for mass concrete, per Caltrans guidance?
- a.About 3 to 5 inches
- b.About 3 to 4 feet
- c.About 15 to 20 inches✓
- d.The full height at once
Caltrans suggests lifts of about 15 to 20 inches for mass concrete and 6 to 20 inches for reinforced members, each consolidated before the next.Caltrans Reinforced Concrete Construction Manual (June 2025), ch. 5
When should an internal vibrator be withdrawn from the concrete?
- a.When paste nears the head's top✓
- b.When bubbles stop entirely
- c.After exactly one minute
- d.As soon as it touches the bottom
Caltrans says paste accumulates around the vibrator, usually in 5 to 15 seconds, and when it appears near the top of the head the vibrator is withdrawn at about the rate it descended.Caltrans Reinforced Concrete Construction Manual (June 2025), ch. 5
Compared with a high-slump mix, how much vibration does a low-slump mix need?
- a.More vibration✓
- b.No vibration
- c.Only external vibration
- d.Less vibration
Caltrans states that to get the same consolidation, low-slump concrete requires more vibration than concrete with a higher slump.Caltrans Reinforced Concrete Construction Manual (June 2025), ch. 5
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Concrete is placed around epoxy-coated reinforcement. What kind of vibrator head is required?
- a.A rubber- or plastic-coated one✓
- b.A bare steel head only
- c.No vibrator may be used
- d.An oversized steel head
Where epoxy-coated rebar is used, vibrators must be coated with plastic or hard rubber to avoid damaging the coating.Caltrans Reinforced Concrete Construction Manual (June 2025), ch. 5
Before new concrete is placed against a hardened construction joint, what must be removed?
- a.The reinforcing steel
- b.Laitance and loose material✓
- c.Every trace of moisture
- d.All surface texture
Caltrans requires construction joint surfaces to be abrasive-blast cleaned to remove laitance and other materials that hinder bond; a roughened surface improves it.Caltrans Reinforced Concrete Construction Manual (June 2025), ch. 5
Ice replaces part of the mixing water on a hot day. What must be true before the truck discharges?
- a.All the ice has melted and mixed.✓
- b.The ice was added at the site.
- c.Half the ice has melted.
- d.The ice is still visible.
Caltrans requires any ice to be completely melted and mixed before the mixer discharges; unmelted ice leaves water pockets.Caltrans Reinforced Concrete Construction Manual (June 2025), ch. 5
Hot water is used in cold weather. Why should it not hit the cement directly?
- a.It lowers the air content.
- b.It stops the cement hydrating.
- c.Flash set or cement balls✓
- d.It cools the aggregate.
Direct contact of hot water and cement may cause premature (flash) set or cement balls, so water and most of the aggregate go in before the cement.Caltrans Reinforced Concrete Construction Manual (June 2025), ch. 5
What does bull floating do right after screeding?
- a.Cuts the contraction joints
- b.Seals the surface for curing
- c.Smooths large areas✓
- d.Adds the broom texture
Bull floats are larger floating devices used to finish large and hard-to-reach areas right after strike-off; texture, jointing and curing come later.Caltrans Reinforced Concrete Construction Manual (June 2025), ch. 5
What does an edging tool produce on a slab?
- a.A nonslip grit surface
- b.Contraction joint grooves
- c.Rounded or beveled edges✓
- d.A stamped pattern
Caltrans defines edging as shaping concrete edges with an edging hand tool to produce smooth rounded or beveled edges; grooving tools make contraction joints.Caltrans Reinforced Concrete Construction Manual (June 2025), ch. 5
When is steel troweling done in the finishing sequence?
- a.Immediately after strike-off
- b.After the concrete has partly hardened✓
- c.While bleed water is on the surface
- d.Before bull floating
Troweling brings a thin layer of mortar to the surface using a metal float or trowel after the concrete has partially hardened; working bleed water in weakens the surface.Caltrans Reinforced Concrete Construction Manual (June 2025), ch. 5
A second coat of curing compound is needed for full coverage. How should it be sprayed?
- a.Diluted with water
- b.In the same direction as the first
- c.At right angles to the first coat✓
- d.Only along the edges
Caltrans says a needed second coat should be applied perpendicular to the first coat for effective coverage; curing compound must not be diluted.Caltrans Reinforced Concrete Construction Manual (June 2025), ch. 5
Why is white-pigmented curing compound often preferred on hidden surfaces?
- a.It dries clear on colored concrete.
- b.It bonds tile better.
- c.It shows coverage and reflects sun.✓
- d.It makes the concrete stronger.
The white pigment makes it easy to see complete coverage and reduces temperature rise by reflecting sunlight. It is not used where appearance or bonding matter.Caltrans Reinforced Concrete Construction Manual (June 2025), ch. 5
A 24-inch-thick footing is cured with its forms left in place, Caltrans method. How long must the forms stay?
- a.At least 14 days
- b.At least 5 days✓
- c.At least 3 days
- d.At least 7 days
The forms-in-place method requires at least 5 days for structures over 20 in in least dimension and 7 days for smaller ones; a 24-in footing qualifies for 5.Caltrans Reinforced Concrete Construction Manual (June 2025), ch. 5
Which ASTM standard does the federal guide specification cite for sampling freshly mixed concrete?
- a.ASTM C143
- b.ASTM C172✓
- c.ASTM C1074
- d.ASTM C39
The specification collects samples of fresh concrete per ASTM C172. C39 is the compression test of cylinders, C143 the slump test, and C1074 the maturity method.UFGS 03 30 00 Cast-in-Place Concrete (Chg 10, Aug 2025)
In hot weather, where should concrete temperature be tested under the federal guide specification?
- a.Delivered and in the forms✓
- b.Only at the batch plant
- c.Only in the cylinders
- d.Only after curing starts
The specification says to test the concrete delivered and the concrete in the forms, and in hot or cold conditions for each batch or every 20 cu yd until the specified temperature is obtained.UFGS 03 30 00 Cast-in-Place Concrete (Chg 10, Aug 2025)
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
Which written safety program must every California employer maintain?
- a.A stormwater pollution plan
- b.A quality control manual
- c.An Injury and Illness Prevention Program✓
- d.A traffic control plan
Title 8 §1509 requires every employer to establish, implement and maintain an effective IIPP under GISO §3203. The other plans apply only in particular situations.Cal. Code Regs. tit. 8, §1509
What must a construction employer's first-aid kit be kept in?
- a.A locked office cabinet
- b.The foreman's truck only
- c.A weatherproof container✓
- d.Any cardboard box
Title 8 §1512 requires at least one first-aid kit in a weatherproof container, regularly inspected and restocked.Cal. Code Regs. tit. 8, §1512
Who must select and provide hand protection against chemical burns from wet cement?
- a.The building inspector
- b.The employer✓
- c.The cement supplier
- d.The worker
GISO §3384 requires employers to select, provide and require appropriate hand protection where hands are exposed to hazards such as chemical burns.Cal. Code Regs. tit. 8, §3384
A worker develops a worsening skin rash after years of handling cement. What is a likely cause?
- a.Silica in the fresh concrete
- b.An allergy to hexavalent chromium✓
- c.Too little water in the mix
- d.Low air content
Some workers become allergic to the hexavalent chromium in cement; the allergy can appear after years and worsen with each exposure.CPWR/eLCOSH, Cement Hazards and Controls
Wet cement gets on a worker's forearm. What should be done?
- a.Rinse it in the tool bucket.
- b.Cover it with a glove.
- c.Wash it off with cool, clean water.✓
- d.Wipe it with a dry rag later.
Skin in contact with wet cement should be washed immediately with large amounts of cool, clean water; tool-bucket water is full of cement.CPWR/eLCOSH, Cement Hazards and Controls
A laborer uses a handheld wet saw indoors for 2 hours. Under Table 1, what respirator is needed?
- a.A dust mask only
- b.A supplied-air hood
- c.APF 10 respirator✓
- d.None, under 4 hours
For handheld power saws with integrated water used indoors or in an enclosed area, Table 1 requires APF 10 for any duration; the 4-hour threshold applies outdoors.Cal. Code Regs. tit. 8, §1532.3
Under Cal/OSHA's silica rule, what makes someone a competent person?
- a.Has worked 10 years
- b.Holds a college degree
- c.Owns the company
- d.Can spot and fix silica hazards✓
A competent person can identify existing and foreseeable silica hazards and has authorization to take prompt corrective measures; both knowledge and authority are needed.Cal. Code Regs. tit. 8, §1532.3
On an 85 °F day, a finisher feels overheated and wants to rest in the shade. What does the heat rule say?
- a.Only at scheduled breaks.
- b.Allow and encourage the rest.✓
- c.Only with a doctor's note.
- d.Only above 95 °F.
Employees must be allowed and encouraged to take a preventative cool-down rest in the shade whenever they feel the need; the 95 °F threshold is for high-heat procedures.Cal. Code Regs. tit. 8, §3395
About how long does acclimatization to heat take for most people, under the heat rule's definition?
- a.Four to fourteen days✓
- b.One full season
- c.One to two hours
- d.Thirty days
Title 8 §3395 states acclimatization peaks in most people within four to fourteen days of regular work for at least two hours a day in the heat.Cal. Code Regs. tit. 8, §3395
A saw operator's noise exposure exceeds Cal/OSHA's Table N-1. What must the employer use first?
- a.Earplugs only, in every case
- b.A shorter lunch break
- c.Nothing if the job is outdoors
- d.Feasible noise controls✓
When sound levels exceed Table N-1, feasible administrative or engineering controls must be used; if they fail to bring levels within the table, personal protective equipment is provided and used.Cal. Code Regs. tit. 8, §5096
A worker will place concrete on a wall top 8 ft above grade with no guardrail. What is required?
- a.Personal fall protection✓
- b.Nothing under 10 ft
- c.A spotter below
- d.A hard hat only
Title 8 §1670 requires personal fall arrest, restraint or positioning systems where workers are exposed to falls in excess of 7½ feet.Cal. Code Regs. tit. 8, §1670
Where must the mid-rail of a standard guardrail be?
- a.Anywhere below 30 inches
- b.Halfway between top rail and floor✓
- c.At the same height as the top rail
- d.Six inches above the floor
Title 8 §1620 places the mid-rail halfway between the top rail and the floor, platform, runway or ramp.Cal. Code Regs. tit. 8, §1620
A contractor uses round rebar caps. What minimum diameter must they have?
- a.3 inches
- b.2 inches
- c.1½ inches
- d.4½ inches✓
Title 8 §1712 requires protective covers of at least 4 × 4 in square or, if round, at least 4½ in in diameter.Cal. Code Regs. tit. 8, §1712
What safety system must every concrete pump have under Title 8?
- a.An emergency stop system✓
- b.A fire extinguisher only
- c.A second operator
- d.A backup alarm only
Title 8 §1720 requires each machine to be equipped with an emergency stop system, with stops at the control panels and remote control.Cal. Code Regs. tit. 8, §1720
A crane is lowering a concrete bucket into position. Where may workers stand?
- a.Not under the bucket✓
- b.Directly under it to guide it
- c.On the bucket rim
- d.Under it if wearing hard hats
No employee may work under concrete buckets while they are being elevated or lowered into position, and riding buckets is prohibited.Cal. Code Regs. tit. 8, §1720
When must haulage vehicles be checked for brakes, lights and other safety equipment?
- a.Only after an accident
- b.Only at annual inspection
- c.Once a month
- d.Start of each shift✓
Title 8 §1593 requires vehicles in use to be checked at the beginning of each shift for safe operating condition.Cal. Code Regs. tit. 8, §1593
A small truck without an automatic backup alarm must back up where the driver can't see behind it. Which option does Title 8 allow?
- a.Honking once before backing
- b.Turning on the headlights
- c.A spotter in clear view✓
- d.Backing slowly without help
Where rear vision is obstructed and there is no automatic alarm or braking device, administrative controls such as a spotter in clear view of the operator may be used.Cal. Code Regs. tit. 8, §1592
A laborer carries a long aluminum screed near a 12,000-volt overhead line. Under the general clearance table, how close may it come?
- a.No closer than 1 foot
- b.No closer than 6 feet✓
- c.No closer than 2 feet
- d.Any distance if gloved
Title 8 §2946 Table 1 sets 6 ft for general activities near lines from 600 to 50,000 volts; boom-type equipment uses Table 2 (10 ft).Cal. Code Regs. tit. 8, §2946
Flaggers work a curb job after dark. What must their warning garments be?
- a.Retroreflective✓
- b.Orange only
- c.Not required at night
- d.Any bright color
During hours of darkness, warning garments must be retroreflective and meet the ANSI/ISEA high-visibility standard, and flagger stations must be lit.Cal. Code Regs. tit. 8, §1598
Where should waste solvent rags and empty sealer cans go on a jobsite?
- a.A storm drain inlet
- b.The concrete washout
- c.The general debris pile
- d.Covered, separate containers✓
Title 8 §1513 requires flammable or hazardous wastes to be placed in covered containers separate from normal debris.Cal. Code Regs. tit. 8, §1513
A mixer with lockable controls needs a repair. What does Title 8 require?
- a.Turn it off and post a sign only.
- b.Have a helper watch the switch.
- c.Lock it out in the off position.✓
- d.Leave it running at idle.
Machines with lockable controls must be locked out or positively sealed in the off position during repair work and setting-up operations.Cal. Code Regs. tit. 8, §3314