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Flashcards in Asphalt Deck (46)
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1

Asphalt

Petroleum Based cementitious material that is mixed with aggregate to form the pavement

2

Common names for Asphalt

Asphalt, asphalt pavement, asphalt concrete, bituminous Concrete

3

Is Asphalt Flexible or Rigid?

Flexible

4

ASTM

American Society for Testing and Materials

5

AASHTO

American Association of State Highway and Transportation Officials

6

Thermoplasticity

Deforms under loads
Liquefies with heat
Asphalt is a flexible type of pavement

7

Viscosity

a measure of a fluid's resistance to flow

directly influenced by the temperature

Temperature increase means a decrease in viscosity

8

Asphalt Grades

Degrees of Hardiness Grading for use-type

9

Asphalt Weathering

Oxidation and evaporation of hydrocarbons causes: Loss of plasticity
Become Brittle with Age

10

How to avoid weathering in Asphalt?

Slope subbases and subgrades
Proper compaction of layers
Timely sealing

11

Asphalt Insolvency

Resistant: Water, Salts, Acids, Alkalis
Susceptible: Petroleum
Remedy: Tar Sealer

12

Asphalt Color

Black

13

Selection Criteria for Asphalt Cements or Binder

Local Standards and practices

14

Fine Aggregate (Flows through No. 8 Sieve)

Mineral Dust
Mineral Filler

15

Coarse Aggregate (Retained by #8 Sieve)

Major Stabilizer

16

Macadam Aggregate

Coarse Aggregates of uniform size of 1.5-2.5”
Coarse wearing surface
Mixed with asphalt cement

17

Fine-graded Aggregate

Finer texture
Less road noise

18

Coarse-Graded Aggregate

Stable pavement
Coarser surface texture
More road noise

19

Dense-Graded Aggregate

Durable
Watertight surface
Highly stable

20

Open-Graded Aggregate

Little or no mineral filler
Larger aggregates
Good strength
Rough texture
High permeability
Used in regions free of frost/thaw conditions

21

Recycled Glass as Aggregate

Works well in asphalt pavements of heavy use

22

Aggregate Hardiness (Toughness)

Ability to withstand loads and wear

23

Resistance to Stripping

Hydrophilic aggregates tend to strip away from the asphalt bond, reducing stability and skid resistance

Compounds (admixture?) added to asphalt mixtures

24

Surface Texture

Rough surface aids in bonding, stability, resistance to skidding and abrasion

25

Crushed Shape Aggregate

Interlock and give the pavement more strength

26

Asphalt Paving Mixtures: Asphalt Concrete

Most Common asphalt paving mixture

27

Asphalt Paving Mixtures: Surface Treatments

Color coating, sealing, improving skid resistance, or prolonging the service life of a fair to good pavement surface

28

Asphalt Paving Mixtures: Paving Blocks

Pre-molded
Used for Pedestrian Paving

29

Asphalt Paving Mixtures: Asphalt-treated Granular Base Courses

Less cost
Can be treated with asphalt cement to produce a stabilized base course

30

Typical Pavement Sections

(1)Layered Asphalt-Aggregate mixtures over a subgrade/improved subgrade
(2)Layered Asphalt-Aggregate mixtures over an aggregate base over a subgrade
(3)Layered Asphalt-Aggregate mixtures over existing pavement

31

Pavement Functions

Support loads
Smooth
Resistant to weathering

32

Minimum total Thickness of the Combined Asphalt Concrete Layers

The minimum total thickness of the combined asphalt concrete layers is 3” - 4”

33

Full-Depth Design

Asphalt aggregate mixture placed directly on a subgrade

34

Aggregate Base Design

Asphalt concrete placed on an untreated aggregate base over the prepared subgrade
Used in locations with frost action

35

Traffic Class I

Parking Lots, Driveways, Light Traffic, Residential Streets, Farm Roads

36

Traffic Class II

Residential Streets, Rural Farm and Residential Roads

37

Traffic Class III

Urban Minor Collector Streets

38

Traffic Class IV

Urban Minor Arterial and Light industrial Streets, Rural Major Collector, Minor arterial Highway

39

Traffic Class V

Urban Freeways, Expressways, Principal Arterial Highways, Urban interstate Highways, Some Industrial Roads

40

Road Thickness Design Procedure

Classify the traffic
Classify the subgrade
Determine Optimum asphalt concrete specs
Determine the thickness

41

Bike Paths and Walkway Width

3”-4” Wide
Use local codes and requirements

42

Golf Cart Paths

Surface a sand-asphalt mixture

43

Tennis Courts

Asphalt-concrete base of 0.75” of nominal maximum size designation covered either with sand-asphalt for the surface course or with a proprietary surfacing

Base course 3”
Surface course 1”

44

Asphalt Curbs

Back-filled with a solid granular material or well-compacted soil

Install on top of a solid, impervious pavement

45

Asphalt Gutters

Can be formed in a variety of cross-sections

46

Asphalt Underlayments

Asphalt Concrete is often used as an underlayment for surface courses