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A- General Engineering License > Asphalt Paving > Flashcards

Asphalt Paving Flashcards

1
Q

What time of day is the best time for pavement removal?

A

Mid-day

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2
Q

Before paving, a string line guide must be set at ___ inches from the center line.

A

6 inches (so it doesn’t get paved over)

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3
Q

Asphaly can be liquified by____

A

Applying extreme pressure

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4
Q

Asphalt is sprayed at a rate of what gal per yard?

A

0.10 to 0.15 gallons per yard

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5
Q

Hot melt bitument adhesive shall be used to cemet pavement markers to the existing pavement at a temperature between?

A

400 - 425 degrees F

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6
Q

What air void percentage will make the mix permeable to air and water and as a result not have the required durability?

A

Air entrainment above 7-8%

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7
Q

What is a good release agent to clean the haul truck?

A

Lime water

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8
Q

Asphalt concrete should be compacted before the mix temperature falls below what temperature?

A

175 degrees F

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9
Q

Besides proper drainage, what is the most important maintenace procedure?

A

Crack Sealing

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10
Q

What is an effective way to repair a pavement with polished aggregate?

A

Cover the surface with a skid resistent treatment

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11
Q

What is the total weight percentage of aggregate to the mixture?

A

90-95%

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12
Q

What happens after the application of the tack coat?

A

Let the water evaporate before placing the overlay

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13
Q

On average, increasing the water in a batch of concrete by 3% (one gallon of water per cubic yard) increases the slump by?

A

1”

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14
Q

The three main mix design methods?

A
  1. Marshall
  2. Hveem
  3. Superior Performing Asphalt Pavement (SHRP)
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15
Q

Penetration System?

A

The stiffness of the asphalt by an indentation measured by a standard needle in units of 0.1mm or 1.0mm and is determined at 77F. Stiffer = low penetration

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16
Q

Grading System?

A

Viscosity is defined by a viscosity measurement at 140F on the material in its original condition (AC) or on a binder considered to be comparable to th ebinder after it passes through the hot-mix process (AR).

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17
Q

Performance grading system?

A

Included in this new set of specifications are tests used to measure physical properties that can be related directly to field performance by engineering principles.

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18
Q

Binder’s temperature susceptibility

A

A material that exhibits a large change in viscosity for a small change in temperature

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19
Q

Aggregate surface texture is the most importatant factor contributing to its frictional resistance and influences

A

the resistance to rutting and ease of compaction (smooth = higher resistance and easy to compact)

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20
Q

Gradation

A

Particle size distribution

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21
Q

VFA

A

Voilds filled with asphalt

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22
Q

Marshall Method

A
  1. Design procedure for airfield pavements in WWII
  2. Mixes are preapred over a range of binder contents using impact compaction
  3. 75 compaction hammer blows per side
  4. Density vs. asphalt content
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23
Q

Hveem Method

A
  1. Caltrans developed for Highways -1940s
  2. stability fn(surface texture)
  3. 4% air voids minimum
  4. Kneading compaction
24
Q

Superpave Method

A
  1. New construction and overlays
  2. Volumetric design and performance tests
  3. Compacted with gyrator compactor
  4. Design number of gyrations to produce 4% grade
25
Q

Prime coat for base preparation on new HMA acts as what? And when and how should it be applied?

A

It acts as a temporary waterproofing layer that protects the base course and prevents it from absorbing water. Prime coat material should be applied 48 hours prior to paving. Cutback asphalt is used and applied at 0.15gal/yd2 or 0.40 gal/yd2. Must be absorbed within 24 hours or blotted with sand or removed.

26
Q

If potholes are deeper than 4” how should the mix be placed?

A

The mix should be placed in more than one layer and each layer compacted.

27
Q

What is a leveling course?

A

Designed to fill in the low spots on the existing pavement surface. The areas with thicker mix will typically compact more than areas with thinner mix.

28
Q

The rule of thumb is that conventional mixes will compact approximately:

A

6mm per 25mm (1/4inch per 1 inch) of compacted thickness l:

29
Q

What is the % difference between milled and unmilled surfaces and the increased quantity of tack coat?

A

The quantity is a function of the type, number, condition, and spacing of the teeth - typically 20-30% more.

30
Q

What is the tack coat and proper install technique?

A

It ensures the bond between the existing pavement surface the new asphalt overlay. Material is asphalt emulsion, asphalt cement or cut-back asphalt. Applied by pressure distributor with all nozzles fully open and turned at the same angle at approximately 30 degrees

31
Q

Batch Plant components?

A

Cold feed system, asphalt cement supply system, aggregate dryer, mixing tower, and emission control system. Total mixing time is 35 seconds. Aggregate and hot air flow in opposite direction in a tower.

32
Q

Parrallel- Flow Drum-Mix Plant Components?

A

Cold feed system, asphalt cement supply system, drum mixer, surge or storage silos, and emission control systems. Aggregate and Hot Air flow in same direction in the drum mixer.

33
Q

Counter-flow drum mix plant components?

A

Aggregate enters drum from upper end, burner is located near the lower end and aggregate flows against the flow of the exhaust gases.

34
Q

A general rule for auger height?

A

The auger should be set as low as possible to minimize the amount of mix carried in the auger chamber. However the bottom of the auger should never be even with or lower than the top of the mix being laid.

35
Q

What is the residual tack coat rate?

A

The amount of asphalt cement remaining on the pavement surface after the water has evaporated.

36
Q

What is the most important factor in obtaining a bond between the existing pavement surface and new overlay? And the ratio of emulsion?

A

The amount of asphalt cement left on the pavement surface after the water has evaporated from the emulsion. Emulsion is approximately two-thirds asphalt cement and one-third water.

37
Q

What is the ratio between the movement of the tow points and the change in the angle of attack of the front edge of the pacer screed?

A

8:1 ratio - if the tow point moves 1 inch, the angle of attack of the screed will be increased by 1/8 inch

38
Q

How many tons of asphalt can a material transfer vehicle hold?

A

35 tons

39
Q

What is the reaction time of the screed when a change is made in its angle of attack?

A

After the tow points have been raised, it takes approximately 5 times the length of the leveling or tie arms to complete 99% of the change for the screed

40
Q

HMA transverse joint

A

Constructed whenever the paving operation is interrupted for a period of time.

41
Q

HMA longitudinal joint

A

Built when a lane is constructed adjacent to the previously placed lane of mix

42
Q

What is the ratio of a tapered joint: length:thickness?

A

12: 1

A mix that is 1” thick requires the length of the taper to be at lest 1ft in length

43
Q

For hand compacted mix, the level of loose mix should be placed at least _____” higher than the surrounding pavement for each 1 inch compacted later thickness.

A

3/8”

44
Q

As a rule of thumb, HMA is expected to densify approximately ___% under the action of compaction equipment

A

20%

Mix must be placed about 1-1/4” thick to produce a 1” thick mat

45
Q

Starting blocks should be about _____ % of that compacted HMA layer.

A

125%

46
Q

Compaction of the unconfined edge of a longitudinal joint should be compacted as much as the rest of the lane.

The edge of the drums should extend over the free edge of the lane at least ____ inches

A

6”

47
Q

The unconfined edge of the mix that passes out from the end gate on the pacer typically slopes at a what degree angle?

A

60

48
Q

The longitudinal edge of the previously placed mix is cut back for a distance of what if there is lack of density.

A

2 - 6 inches with a cutter on the roller

49
Q

Typical overlap on longitudinal joints?

A

1 to 1-1/2”

50
Q

What is echelon paving?

A

Two pavers running next to each other in adjacent lanes

51
Q

The minimum course thickness that should be specified under the best of circumstances is? And in early spring or late fall?

A

1-1/2” and 2” in cooler weather

52
Q

For a vibratory roller, for a given amplitude, changing the frequency influences the dynamic force to?

A

The second power

53
Q

How do you find the impact spacing for a vibratory roller?

A

= speed (m/min) / frequency of vibrations

54
Q

Number of passes needed to cover a mat surface?

A

Mat width / width of compaction drum

55
Q

Modern standard practice is to have each roller overlap its own pass by a minimum of:

A

6 - 12 inches

56
Q

Based on the superpave mixes what is the mid temperature range?

A

200-240F

A- General Engineering License (13 decks)

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