Virginia Concrete Contracting Qualified Individual Examination

Under 18VAC50-22-30, what work does Virginia Concrete Contracting (CEM) cover?

• AOnly decorative stamped patios and colored walkways on residential lots
• BAll work in connection with processing, proportioning, batching, mixing, conveying, and p…
• COnly ready-mix plant operation, with placement left to a highway/heavy contractor
• DBrick, block, and stone masonry, including mortarless masonry units

Which of the following is expressly included in the Virginia CEM specialty definition?

• AInstallation of a new building electrical service and panel
• BConstruction and assembling of forms, molds, slipforms, and pans, centering, and the use…
• CLaying structural CMU walls and tuck-pointing brick veneer
• DInstalling interior plumbing and sanitary waste piping

Besides a CEM specialty contractor, which Virginia Board for Contractors classifications also provide the concrete contracting function?

• AOnly Electrical (ELE) and Plumbing (PLB)
• BOnly Painting and Wallcovering (PTC)
• CCommercial Building Contractor (CBC), Residential Building Contractor (RBC), and Highway/…
• DOnly Asbestos (ASB) and Lead Abatement (LAC)

A CEM-only firm is hired to place a warehouse floor slab. Which additional task is outside CEM and requires another classification or specialty?

• ASaw-cutting control joints in the new slab
• BPlacing a polyethylene film barrier under the slab
• CInstalling the building electrical service and branch circuits
• DApplying a concrete sealer to the finished slab

Which group of concrete operations is included in the Virginia CEM specialty?

• AFinishing, coloring, curing, repairing, testing, sawing, grinding, and grouting
• BOnly mixing at a central plant, with no field finishing or testing
• COnly demolition of existing masonry chimneys
• DOnly installation of ceramic tile over a cured slab

A specification calls for a polyethylene film vapor retarder under a slab-on-ground. How does that task fit the Virginia CEM specialty?

• AIt is outside CEM and requires an insulation (INS) specialty
• BIt is outside CEM and requires a roofing (ROC) specialty
• CIt is included because CEM covers placing of film barriers, sealing, and waterproofing
• DIt is allowed only when a CBC contractor is also on the permit

A customer wants a cast-in-place concrete retaining wall and a separate face of clay brick veneer. Which licensing split is correct under Virginia specialty definitions?

• ACEM covers both the cast concrete wall and the clay brick veneer
• BCEM covers the cast concrete wall; the clay brick veneer is masonry contracting (BRK)
• CBRK covers both the cast concrete wall and the brick veneer
• DOnly Highway/Heavy may place any retaining wall concrete

Which statement best describes how CEM relates to steel erection (STL) on a reinforced concrete job?

• ACEM includes the use of rebar as part of concrete work; STL is a separate specialty that…
• BOnly STL may touch reinforcing steel on any Virginia project
• CCEM includes structural steel columns and crane-erected beams
• DCEM and STL are identical specialties with the same definition

If two otherwise similar mixes differ only in water-cement ratio, which mix is expected to have higher compressive strength and lower permeability?

• AThe mix with the higher water-cement ratio
• BThe mix with the lower water-cement ratio
• CThe mix with the higher slump, regardless of water-cement ratio
• DThe mix with more entrapped air voids

What does a slump test primarily measure on fresh concrete?

• A28-day compressive strength
• BAir content as a percent of volume
• CConsistency and workability of the fresh mix
• DThe exact water-cement ratio of the batch

Why is intentionally entrained air used in exterior concrete exposed to freezing and thawing in the presence of moisture?

• ATo raise the water-cement ratio so the mix is easier to pump
• BTo provide microscopic air voids that relieve freezing-water pressure in the paste
• CTo replace all coarse aggregate in the mix
• DTo eliminate the need for any curing

A one-cubic-yard batch contains 564 pounds of cement and 282 pounds of mixing water. What is the water-cement ratio by weight?

• A0.40
• B0.45
• C0.50
• D0.55

In U.S. ready-mix practice, how much does one standard sack of portland cement weigh?

• A50 pounds
• B80 pounds
• C94 pounds
• D100 pounds

What is the primary reason to use a water-reducing admixture instead of adding extra mixing water?

• ATo raise slump or keep workability without increasing the water-cement ratio
• BTo replace air-entraining admixture in freeze-thaw concrete
• CTo stop hydration so the concrete never sets
• DTo eliminate the need for consolidation

A specified mix uses 564 pounds of cement per cubic yard at a water-cement ratio of 0.45. How many pounds of mixing water are required per cubic yard?

• A226 pounds
• B254 pounds
• C282 pounds
• D310 pounds

A high-range water reducer (superplasticizer) is added at the job. What is the intended effect?

• AA large slump increase at the same water content, or a large water cut at the same slump
• BA guaranteed increase in entrained-air content of 8 to 10 percent
• CImmediate flash set so finishing can start in the chute
• DConversion of the mix from normalweight to lightweight concrete

On a hot Virginia afternoon, the batch plant adds a retarding admixture. What is the main purpose?

• ATo speed initial set so the crew can strip wall forms in one hour
• BTo slow hydration so the concrete stays plastic long enough to place and finish
• CTo entrain freeze-thaw air in place of an air-entraining agent
• DTo increase the water-cement ratio without adding water

A trial batch of all mix ingredients occupies 28.35 cubic feet. Using 27 cubic feet per cubic yard, what is the yield of that batch?

• A0.95 cubic yards
• B1.00 cubic yards
• C1.05 cubic yards
• D1.15 cubic yards

Why is calcium chloride often restricted or prohibited as an accelerating admixture in reinforced concrete?

• AIt always prevents the concrete from setting
• BChloride ions can promote corrosion of embedded reinforcing steel
• CIt is the only admixture that entrains freeze-thaw air
• DIt lowers slump so far that the mix cannot be placed

Fly ash or ground-granulated blast-furnace slag is added as a supplementary cementitious material. What is a typical field effect compared with a straight portland-cement mix at the same total cementitious content?

• AOften slower early strength with improved long-term strength and lower permeability when…
• BInstant 1-day strength equal to Type III cement with no curing required
• CComplete elimination of the need for air entrainment in freeze-thaw exposures
• DConversion of the slump test into a strength test

How does intentionally entrained air differ from entrapped air in fresh concrete?

• AEntrained air is a system of tiny, dispersed bubbles from an air-entraining admixture; en…
• BEntrapped air is specified at 5 to 7 percent for freeze-thaw durability; entrained air is…
• CThe two terms mean the same thing and are interchangeable on tickets
• DEntrained air only occurs in lightweight aggregate and cannot be produced in normalweight…

A mix requires 282 pounds of mixing water per cubic yard. Using 8.34 pounds per gallon for water, about how many gallons of water are needed per cubic yard?

• A25.4 gallons
• B30.1 gallons
• C33.8 gallons
• D40.0 gallons

A specification calls for a 6-sack mix. How many pounds of portland cement are required per cubic yard?

• A376 pounds
• B470 pounds
• C564 pounds
• D658 pounds

A truck arrives 1 inch below the specified slump. The finishers want a hose added to the drum. What is the correct concern?

• AAdded water raises the water-cement ratio, which can lower strength and durability even i…
• BAdded water always increases 28-day strength
• CAdded water has no effect if the extra slump is less than 2 inches
• DAdded water replaces the need to measure air content

What is the basic performance requirement for concrete formwork?

• AIt only needs to look straight after the pour, regardless of bracing
• BIt must be capable of supporting, without failure, the vertical and lateral loads reasona…
• CIt may be braced after the wall is more than half full if the pour is going well
• DIt is required only for slabs on ground, not for walls or columns

Why is freshly placed concrete consolidated, usually by internal or external vibration?

• ATo drive out entrapped air and make the concrete fill around reinforcement and into corne…
• BTo increase the water-cement ratio after the truck leaves
• CTo create the microscopic freeze-thaw air-void system
• DTo replace specified curing

What is a common result of overvibrating a placement?

• AA uniform increase in specified compressive strength
• BSegregation, with mortar rising and coarse aggregate settling
• CAutomatic air entrainment at 8 percent
• DImmediate 28-day strength in the forms

What is the usual field concern with letting concrete drop freely a long distance into a wall or column form?

• AThe cement hydrates faster because of the fall
• BThe mix can segregate, leaving honeycomb and rock pockets at the bottom
• CSlump always decreases to zero before it lands
• DAir-entraining admixture is activated only by a long drop

Which placing condition most increases lateral pressure on wall forms?

• AA slower pour rate with a stiff mix in warm weather
• BA faster pour rate with a more fluid mix, especially in cooler weather that delays set
• CUsing only internal vibration at widely spaced points
• DPlacing a slab on ground instead of a wall

What is a cold joint in a concrete wall or slab?

• AA planned isolation joint filled with asphalt-impregnated fiber
• BA plane of weakness where a new placement meets concrete that has already stiffened so th…
• CA saw-cut control joint made the next morning
• DA construction joint that was deliberately keyed and dowelled while both sides were plast…

When placing a tall wall in lifts, how should the vibrator be used at the lift line?

• AKeep the vibrator entirely in the new lift and never penetrate the lift below
• BPenetrate the previous lift a short distance while that concrete is still plastic so the…
• CLay the vibrator on the form face and run it continuously for the whole pour
• DUse the vibrator to drag concrete horizontally along the wall

A formed wall is 8 inches thick, 10 feet high, and 40 feet long. How many cubic yards of concrete are required, using 27 cubic feet per cubic yard and no waste?

• A8.0 cubic yards
• B8.9 cubic yards
• C9.9 cubic yards
• D12.0 cubic yards

A continuous footing is 2 feet wide, 1.5 feet deep, and 48 feet long. How many cubic yards are required with no waste?

• A3.6 cubic yards
• B5.3 cubic yards
• C7.1 cubic yards
• D8.0 cubic yards

A square column is 18 inches by 18 inches and 12 feet high. How many cubic yards of concrete does one column require with no waste?

• A0.50 cubic yards
• B0.75 cubic yards
• C1.00 cubic yards
• D1.50 cubic yards

What is the main structural job of form ties in a wall form?

• ATo color the finished wall
• BTo resist the bursting (lateral) pressure that tries to spread the form faces apart
• CTo replace vertical strongbacks and wales entirely
• DTo act as the only reinforcing steel in the wall

Why are chamfer strips commonly placed in the corners of column and wall forms?

• ATo increase the column's design load by 50 percent
• BTo create a broken corner that is less likely to spall and is easier to strip
• CTo replace all column ties and hoops
• DTo act as the vapor retarder

A pump operator reports that the mix will not move without adding water at the hopper. What is the best first response that protects the specification?

• AAdd unrestricted hose water until the pump sounds happy, then hide the extra water on the…
• BStop and correct workability with an approved high-range water reducer or a mix adjustmen…
• CRaise the boom and increase line pressure while the mix is still too stiff
• DDischarge the load on the ground and finish with site-mixed mortar

During slipform work, what must not be exceeded while concrete is being placed?

• AThe predetermined safe rate of lift
• BThe 28-day compressive strength before the first lift
• CThe slump-cone height of 12 inches
• DThe number of form ties used on a conventional wall

What is the nominal diameter of a #4 reinforcing bar?

• A1/4 inch
• B3/8 inch
• C1/2 inch
• D5/8 inch

What is the main purpose of concrete cover over reinforcing steel?

• ATo hide the bar grade marks from the inspector
• BTo protect the steel from corrosion and fire and to let the bar develop bond with the con…
• CTo replace chairs and other bar supports
• DTo increase slump at the surface

What is the proper use of bar chairs, bolsters, or concrete dobies?

• ATo support reinforcing at the specified elevation and cover before and during placement
• BTo substitute for specified lap splices
• CTo measure slump in the field
• DTo seal control joints after sawing

For concrete cast against and permanently exposed to earth, what cover to reinforcing is commonly specified?

• A3/8 inch
• B3/4 inch
• C1 inch
• D3 inches

What is the correct conceptual rule for a lap splice of reinforcing bars?

• AAny overlap is acceptable if the bars touch for at least 2 inches
• BBars must overlap the length required by the project drawings or specifications so stress…
• CLap splices are never permitted in slabs or walls
• DA lap splice replaces the need for any concrete cover

Why are intersecting reinforcing bars tied with annealed wire?

• ATo add the tensile capacity of the wire to the design strength of the member
• BTo hold the cage or mat in position so bars do not shift during placing and vibration
• CTo create the specified concrete cover without chairs
• DTo replace stirrups and column ties

A footing requires 60 pieces of #4 bar, each 16 feet long. Using 0.668 pounds per foot for #4 bar, what is the total steel weight?

• A401 pounds
• B534 pounds
• C641 pounds
• D802 pounds

A wall schedule calls for 36 pieces of #5 bar, each 20 feet long. Using 1.043 pounds per foot for #5 bar, what is the total steel weight?

• A626 pounds
• B751 pounds
• C834 pounds
• D938 pounds