Asphalt Paving Materials Bituminous Materials Bitumenalso known as - - PowerPoint PPT Presentation

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Asphalt Paving Materials Bituminous Materials Bitumenalso known as - - PowerPoint PPT Presentation

Jun 27, 2023 252 likes •806 views

Asphalt Paving Materials Bituminous Materials Bitumenalso known as asphalt or taris a black, oily, viscous form of petroleum, which is a naturally occurring organic byproduct of decomposed plants. Natural bitumen is the thickest form of

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Asphalt Paving Materials

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Bituminous Materials

Bitumen—also known as asphalt or tar—is a black, oily, viscous form of petroleum, which is a naturally occurring organic byproduct of decomposed plants. Natural bitumen is the thickest form of petroleum there is, and is made up of 83% carbon, 10% hydrogen and lesser amounts of oxygen, nitrogen, sulfur, and other elements.

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Bituminous Materials

Bituminous Materials Natural Asphalts Petroleum Asphalts Tar & Pitch

(late 1800s) (early 1900s) (late 1800s)

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Natural Asphalt

Rock Asphalt Native Asphalt Asphalt Sand

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Rock Asphalt

Asphalt rock is formed when natural layers of petroleum harden in the pores of sedimentary rocks such as limestone or sandstone. Over time, the lighter components evaporate away leaving material that ranges in consistency from a thick liquid to a crumbly sand or stone. Only about 5% to 15% of the composition of asphalt rocks is asphalt.

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Rock Asphalt

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Rock Asphalt

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ROCK ASPHALT & OIL SHALE IN KENTUCKY

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Asphalt Sands

Asphalt sands (also called oil or tar sands) are either loose sands or partially consolidated sandstone containing a mixture of sand, clay, water, and bitumen. It is increasingly used as a source for crude oil thanks to technological developments such as steam extraction.

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Asphalt Sands

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Asphalt Sands

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Asphalt Sands

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Native Asphalt

Native asphalts are seepages of natural asphalt that rise to the surface from deeper oil-bearing rocks and collect in depressions on the ground

  • surface. The lighter components evaporate to

leave behind a viscous or semi-solid deposit. The asphalt is so viscous you can walk on the

  • surface. But if you stand on the surface for too

long, you will slowly sink into it!

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Native Asphalt

CIVL 3137 13 Source: Geological Society of Trinidad and Tobago (www.gstt.org)

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Native Asphalt

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La Brea “Tar” Pits

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Wilshire Blvd

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Pitch Lake, Trinidad

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Pitch Lake, Trinidad

CIVL 3137 17 http://www.flickr.com/photos/striderv/4314238332/lightbox/

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Pitch Lake, Trinidad

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Pitch Lake, Trinidad

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Pitch Lake, Trinidad

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Pitch Lake, Trinidad

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Pitch Lake, Trinidad

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Bituminous Materials

Bituminous Materials Natural Asphalts Petroleum Asphalts Tar & Pitch

(late 1800s) (early 1900s) (late 1800s)

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Tar / Pitch

Tar is a dark brown or black viscous liquid of hydrocarbons and free carbon, obtained from a variety of organic materials such as coal, wood, or peat. The material is heated without

  • xygen (so the source material doesn’t burn)

until the tar liquefies and seeps out.

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Wood Tar

Wood tar (primarily made from pine wood) has many uses as a disinfectant, a flavoring agent for candies and alcohol, a spice for meat, and a water repellant. It is also used in cosmetics and anti-dandruff shampoos. Turpentine and charcoal are the byproducts of wood tar distillation.

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Wood Tar Kiln, Sweden

CIVL 3137 26 https://en.wikipedia.org/wiki/Tar

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Coal Tar

Coal tar is produced by heating coal without

  • xygen to produce coke and oil gas. Coal tar

was used to construct the first surfaced roads. This is where we get the term “tarmac” or “tar macadam”. Today it can still be found in some parking lot sealers though it’s being phased

  • ut due to environmental and health concerns.

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Dunlap, TN Coking Ovens

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Chickamauga Coking Ovens

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Pennsylvania Coking Ovens

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Bituminous Materials

Bituminous Materials Natural Asphalts Petroleum Asphalts Tar & Pitch

(late 1800s) (early 1900s) (late 1800s)

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Petroleum Asphalt

Petroleum asphalt is produced as a byproduct

  • f crude oil distillation. It is the fraction of the

crude oil with the highest boiling point (greater than 500°C) so it represents the residual left

  • ver after everything else (gasoline, kerosene,

diesel, etc.) has boiled off in the distillation process.

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Crude Oil Chemistry

Oils (Hydrocarbons) Resin-coated asphaltenes

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Crude Oil

Aromatic Hydrocarbons (oils) Saturated Hydrocarbons

Light Crude Heavy Crude

“oils” “oils” “oils” “oils”

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Atmospheric Distillation

Tube Heater Topped Crude

38-70 Carbons

Crude Distillation Column Diesel Oil - 270°C

15-38 Carbons

Kerosene - 170°C

10-14 Carbons

Naphtha - 120°C

5-10 Carbons

Gasoline - 70°C

1-4 Carbons

Butane & Propane

1-4 Carbons

 400ºC

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Vacuum Distillation

Heat Bitumen Residuum (Asphalt Cement) Topped Crude

Vacuum

Heavy Gas Oil Medium Gas OIl Light Gas OIl Vaporizes the topped crude without using excessive heat (“cracking”)

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Crude Oil

33 20 16 30 58 6 7 26 21 14 10 28 27 Bitumen Residuum Gasoline Kerosene

  • Lt. Gas Oil
  • Hv. Gas Oil

Boscan Venezuela Arabian Heavy Nigeria Light

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Petroleum Asphalt

Petroleum asphalt at room temperature is very

  • stiff. In order to mix it with aggregate to make

asphalt concrete, it has to be liquefied.

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Liquefying Asphalt Cement

Asphalt Cement (Bitumen Residuum)

Heat it Suspend it in water Thin it with solvents

Hot-Mix Asphalt Emulsified Asphalt Cutback Asphalt

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Temperature-Viscosity

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Peanut Butter Ketchup Chocolate Syrup Honey Tomato Juice Vegetable Oil

AASHTO T-245 MARSHALL MIXING TEMP. RANGE (170 +/- 20 cSt) AASHTO T-245 MARSHALL COMPACTING TEMP. RANGE (280 +/- 30 cSt)

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Liquefying Asphalt Cement

Asphalt Cement (Bitumen Residuum)

Heat it Suspend it in water Thin it with solvents

Hot-Mix Asphalt Emulsified Asphalt Cutback Asphalt

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Cutback Asphalt

Cutback asphalt is asphalt cement that has been blended with a solvent in order to reduce its viscosity. After a cutback asphalt is applied the solvent evaporates leaving behind asphalt cement residue on the surface to which it was

  • applied. A cutback asphalt is said to “cure” as

the petroleum solvent evaporates away.

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Cutback Asphalt

Cutback asphalt is classified according to the rate at which it cures (fast, medium, slow) and the viscosity of the liquid. The curing rate is a function of the boiling point of solvent used. The viscosity is based on how much solvent is used.

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Cutback Asphalt

30

30-60

70

70-140

250

250-500

800

800-1600

3000

3000-6000

Solvent Asphalt

Grade

Kinematic Viscosity @ 140°F (in centistokes)

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Cutback Asphalt

Rapid Curing (RC)

Asphalt cement thinned with gasoline or naphtha Used for tack and seal coats (surface applications)

Medium Curing (MC)

Asphalt cement thinned with kerosene Used for prime coats, cold-laid pavement bases

Slow Curing (SC)

Asphalt cement thinned with diesel oil or gas oils Used for cold-laid pavement bases

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Liquefying Asphalt Cement

Asphalt Cement (Bitumen Residuum)

Heat it Suspend it in water Thin it with solvents

Hot-Mix Asphalt Emulsified Asphalt Cutback Asphalt

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Emulsified Asphalt

Emulsified asphalt is a suspension of very small asphalt cement droplet in water, which is assisted by an emulsifying agent (e.g., soap) that disrupts the surface tension of the water and imparts an electrical charge to the surface

  • f the asphalt cement droplets so that they do

not coalesce into larger droplets and fall out of suspension.

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Emulsified Asphalt

hydrophilic group(s) hydrophobic component

Asphalt droplet

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Emulsified Asphalt

Repulsion between negative surface charges prevents coalescence

Asphalt droplet Asphalt droplet

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Emulsified Asphalt

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Emulsified Asphalt

LIMESTONE SILICA Anionic Emulsifier Cationic Emulsifier

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Emulsified Asphalt

Emulsified asphalts appear as a thick brown liquid when first applied. When the asphalt droplets start to adhere to the aggregate the color changes to black and the emulsion is said to “break” (i.e., separate). As the water evaporates, the emulsion behaves more like pure asphalt cement. Once all the water has evaporated, the emulsion is said to have “set”.

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Emulsified Asphalt

There are three main emulsion grades: rapid set, medium set and slow set. The terms relate to the amount of time it takes for the emulsion to set and the amount of mixing that can be performed before the emulsion breaks. Slow setting emulsions can stand up to more mixing than fast setting emulsions.

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Emulsified Asphalt

Rapid Setting (RS or CRS)

Used for surface coats, penetration macadam

Medium Setting (MS or CMS)

Used for open-graded asphalt-treated base

Slow Setting (SS or CSS)

Used for dense-graded asphalt-treated base