Item 405 Structural Concrete

41 questions • 1 mo ago

Question list

All superstructures and heavily reinforced substructures. The important parts of the structure included are slabs, beams, girders, columns, arch ribs, box culverts, reinforced abutments, retaining walls, and reinforced footings

Class A

Footings, pedestals, massive pier shafts, pipe bedding, and gravity walls, unreinforced or with only a small amount of reinforcement

Class B

Thin reinforced sections, railings, precast R.C. piles and cribbing, and for filler in steel grid floors

Class C

Prestressed concrete structures and members

Class P

Concrete deposited in water

Seal

The measured cement content shall be within ___ of the design cement content

± 2%

As work progresses, at least one sample consisting of _______ concrete cylinder test specimens, ______ shall be taken from each ___ of each class of concrete or fraction thereof placed each day

3, 150mm x 300mm, 75cu.m

Accuracy of batching shall be within ___

± 1%

The accuracy of measuring the water shall be within a range of error of not more than ___

All aggregates whether produced or handled by hydraulic methods or washed, shall be stockpiled or binned for draining for at least 12 hours prior to batching

12 hours

Rail shipment requiring more than 12 hours will be accepted as adequate binning only if the car bodies permit free drainage

12 hours

If the aggregates contain high or non-uniform moisture content, storage or stockpile period in excess of ___ may be required by the Engineer

12 hours

Batching shall be conducted as to result in a ___ maximum tolerance for the required materials

Scales shall be accurate to ___ throughout the range used

0.5%

When cement is placed in contact with moist aggregates, batches will be rejected unless mixed within ___ of such contact

1 - 1.5 hours

Admixtures shall be measured into the mixer with an accuracy of _______

± 3%

The intervals between delivery of batches shall not be so great as to allow the concrete inplace to harden partially, and in no case shall such an interval exceed ___

30 minutes

For small peoject requiring less than ____ cu.m/day of pouring, the weight proportionsshapp be conceeted to equuvalent volumetric proportions

Mixer having a rated capacity of less than a ___ batch shall not be used

1 bag

The volume of concrete mixed per batch shall not exceed the mixer's nominal capacity as shown on the manufacturer's standard rating plate on the mixer except that an overload up to ___ above the mixer's nominal capacity may be permitted, provided concrete test data for strength, segregation, and uniform consistency are satisfactory and provided no spillage of concrete takes place

10%

The flow of water shall be uniform and all water shall be in the drum by the end of the first ___ of the mixing period

15 seconds

Mixing time shall not be less than ___ for mixers having a capacity of ___ or less

60 seconds, 1.5 cu.m

For mixers having a capacity greater than 1.5m³, the mixing time shall not be less than ___

90 seconds

If timing starts, the instant the skip reaches its maximum raised position, ___ shall be added to the specified mixing time

4 seconds

If the timing device is not placed in good working order within ____, further use of the mixer will be prohibited until repairs are made

24 hours

The accuracy of all weighing devices except that for water shall be such that successive quantities can be measured to within ___ of the desired amounts

The water measuring device shall be accurate to ±0.5%

±0.5%

When the entire plant is running, the scale reading at cut-off shall not vary from the weight designated by the Engineer more than ___

When the entire plant is running, the scale reading at cut-off shall not vary from the weight designated by the Engineer more than _____ for the total aggregate in any batch

The pick-up and throw-over blades of mixers shall be restored or replaced when any part or section is worn ______ or more below the original height of the manufacturer's design

20mm

When bulk cement is used and the volume of the batch is _____ or more, the scale and weigh hopper for Portland Cement shall be separate and distinct from the aggregate hopper or hoppers

0.5cu.m

The discharging mechanism shall also be interlocked against the opening when the amount of cement in the hopper is underweight by more than ___

The discharging mechanism shall also be interlocked against the opening when the amount of cement in the hopper is overweight by more than ___ of the amount specified

All water shall be in the drum by the end of the ____ quarter of the specified mixing time

1st

All concrete shall be mixed for a period of not less than ______ after all materials, including water, are in the mixer

1.5 minutes

When mixing is to cease for a period of _____ or more, the mixer shall be thoroughly cleaned

1 hour

Truck mixing, shall, unless otherwise directed, be continued for not less than ___ revolutions after all ingredients, including water, are in the drum

100

The mixing speed shall not be less than ____, nor more than ____

4 rpm, 6 rpm

Mixing shall begin within ______ after the cement has been added either to the water or aggregate

30 minutes

When a truck mixer or agitator is used for transporting concrete to the delivery point, discharge shall be completed within _____ or ___________ of the drum or blades, whichever comes first, after the introduction of the cement to the aggregates

1 hour, 250 revolutions

The rate of interval between batches shall not exceed ______

20 minutes

YT1 Materials Engineer EXAM

Anonymous · 100 questions · 1 mo ago

YT1 Materials Engineer EXAM