ACI Flatwork
It is important that the finisher foreman read and understand project specifications.
If the crew can place and finish 100 yd³ of concrete per hour, the producer's delivery rate should
be about 100 yd³ per hour.
Concrete is sold by the ton? — False
Delays in discharging concrete trucks can result in the concrete being hard to: pump, place, and
finish
When there is room for two concrete trucks ready to discharge into a pump hopper, placement is
faster because: as one truck is finishing, the other is ready to unload the concrete
Concrete from a ready mix truck must usually be completely discharged within 1.5 hours after
water has been added at the plant.
You can tell when water has been added to the concrete truck by looking at the: batch ticket
When concrete for a slab placement will be discharged from the truck chute, truck arrivals
should usually be spaced at about: 15 minutes
When finishers get behind because the concrete is setting faster than expected and the placing
crew is also shorthanded, one solution is slowing the concrete delivery rate to match worker
output. — True
In deciding how much concrete to order for a floor placement, you should calculate the number
of cubic yards needed to fill the forms, then order two to three cubic yards less so you don't
waste concrete that is not needed. — False
The question, "What finisher or finishers can request addition of water to the concrete truck on
site?" should be answered at the Pre-construction meeting.
Concrete made with portland cement will set and harden while under water. — True
If a concrete slab on ground won't be exposed to sulfates, the cement used is most likely to be:
Type I
, Most concrete used in slabs on ground has coarse aggregate with a maximum size of: 3/4 to 1 1/2
in.
Sand for concrete used in slabs on ground is easier to finish when it has close to the largest
allowable amount of material passing the No. 50 and No. 100 sieve. — True
Increasing the amount of sand in a concrete usually decreases the amount of water needed to
make the concrete workable. — False
All concrete that will be subject to freezing when moist or be exposed the deicing salts should
contain: an air-entraining agent
Strength of normal weight concrete depends mainly on: water-cement ratio
Overhanded concrete mixtures are likely to produce floors with poor wear resistance and
excessive shrinkage. — True
To minimize shrinkage and reduce cracking and curling: use as much coarse aggregate as
possible, use as little mixing water as possible, and use aggregates with low shrinkage
Changes in concrete slump most often represent changes in the amount of water in the mixture.
Air-entrained concrete is not recommended for use in concrete slabs: finished by repeated steel
troweling passes
Changes in concrete temperatures affect: setting time, air content, and slump
To determine if concrete, in place, has the strength needed to put it into service, test cylinders
should be: kept at the job site and cured under conditions similar to the curing conditions
for the concrete they represent
Granular sub bases for slabs on ground can be compacted with sheepsfoot rollers. — False
In cold weather, the sub grade soil must be free of frost before concrete placing begins.
Before a concrete slab on ground is placed under severe drying conditions that threaten plastic
shrinkage cracking, water should be sprayed on the sub grade until puddles are formed and the
surface is soft. — False
Before concreting, workers should check the elevation of the subbase by: measuring down from
a straightedge spanning between the side forms
If the surface of the subbase for a concrete slab on ground is too low, the slab is likely to be too
thin. — False
It is important that the finisher foreman read and understand project specifications.
If the crew can place and finish 100 yd³ of concrete per hour, the producer's delivery rate should
be about 100 yd³ per hour.
Concrete is sold by the ton? — False
Delays in discharging concrete trucks can result in the concrete being hard to: pump, place, and
finish
When there is room for two concrete trucks ready to discharge into a pump hopper, placement is
faster because: as one truck is finishing, the other is ready to unload the concrete
Concrete from a ready mix truck must usually be completely discharged within 1.5 hours after
water has been added at the plant.
You can tell when water has been added to the concrete truck by looking at the: batch ticket
When concrete for a slab placement will be discharged from the truck chute, truck arrivals
should usually be spaced at about: 15 minutes
When finishers get behind because the concrete is setting faster than expected and the placing
crew is also shorthanded, one solution is slowing the concrete delivery rate to match worker
output. — True
In deciding how much concrete to order for a floor placement, you should calculate the number
of cubic yards needed to fill the forms, then order two to three cubic yards less so you don't
waste concrete that is not needed. — False
The question, "What finisher or finishers can request addition of water to the concrete truck on
site?" should be answered at the Pre-construction meeting.
Concrete made with portland cement will set and harden while under water. — True
If a concrete slab on ground won't be exposed to sulfates, the cement used is most likely to be:
Type I
, Most concrete used in slabs on ground has coarse aggregate with a maximum size of: 3/4 to 1 1/2
in.
Sand for concrete used in slabs on ground is easier to finish when it has close to the largest
allowable amount of material passing the No. 50 and No. 100 sieve. — True
Increasing the amount of sand in a concrete usually decreases the amount of water needed to
make the concrete workable. — False
All concrete that will be subject to freezing when moist or be exposed the deicing salts should
contain: an air-entraining agent
Strength of normal weight concrete depends mainly on: water-cement ratio
Overhanded concrete mixtures are likely to produce floors with poor wear resistance and
excessive shrinkage. — True
To minimize shrinkage and reduce cracking and curling: use as much coarse aggregate as
possible, use as little mixing water as possible, and use aggregates with low shrinkage
Changes in concrete slump most often represent changes in the amount of water in the mixture.
Air-entrained concrete is not recommended for use in concrete slabs: finished by repeated steel
troweling passes
Changes in concrete temperatures affect: setting time, air content, and slump
To determine if concrete, in place, has the strength needed to put it into service, test cylinders
should be: kept at the job site and cured under conditions similar to the curing conditions
for the concrete they represent
Granular sub bases for slabs on ground can be compacted with sheepsfoot rollers. — False
In cold weather, the sub grade soil must be free of frost before concrete placing begins.
Before a concrete slab on ground is placed under severe drying conditions that threaten plastic
shrinkage cracking, water should be sprayed on the sub grade until puddles are formed and the
surface is soft. — False
Before concreting, workers should check the elevation of the subbase by: measuring down from
a straightedge spanning between the side forms
If the surface of the subbase for a concrete slab on ground is too low, the slab is likely to be too
thin. — False
