ASPHALT 101

Robert B. McGennis, P.E.

The HollyFrontier Companies

Phoenix, AZ

The History of Asphalt

The HollyFrontier Companies

Headquartered in Dallas, TX NYSE: HFC

5 complex/integrated refineries OK, NM, KS, WY, UT

457,000 bpd capacity

6 Asphalt Terminals Artesia, Albuquerque,

Pena Blanca, NM

Glendale, AZ

Catoosa, OK

Cheyenne, WY Who are those guys?

Once upon a time in Trinidad…

Earliest Asphalt Binder Specs Addressed TLA (and similar)

Color

Solubility in carbon disulfide

Asphalt Manufacture

Standard Oil Richmond, CA 1914

Penetration Test and Spec (1920s – 1970s)

Penetration Grades: AASHO M20

40 - 50

60 - 70

85 - 100

120 - 150

200 - 300

hard

er

100 g 100 g

Penetration

0.1 mm

0 sec 5 sec

run test at 25 C (77 F)

The Problem with Pen Spec

25 60 135 -15

Consistency

(pen)

hard

soft

pen

A B

C

Temperature, C

This is all

we see in

this system…

they all look

the same!

The Problem with Pen Spec

25 60 135 -15

Consistency

(pen)

hard

soft

pen

A B

C

Temperature, C

Asphalt Manufacture

HollyFrontier El Dorado, KS 2015

Fractional Distillation

Crude

Oil

Crude

Furnace

Distillation Column

Gas

Naphtha

Gasoline

Kerosene

Diesel

Lubricating Oil

Heavy Gas Oil

Residue

4

6

8

12

16

36

44

70+

Carbons

700 F

100 F

600 F

200 F

300 F

400 F

500 F

Vapor

Cooled Reflux

Cooled Reflux

Cooled Reflux

Cooled Reflux

Liq

uid

Source: Tom Shetina, HFC

What a Modern Refinery Does

A refinery maximizes the conversion of crude oil into desirable products (transportation fuels)

Residue ~ 37%

Lube Oil ~ 15%

Jet & Diesel ~ 21%

Gasoline ~ 25%

LPG ~ 2%

Residue ~ 8%

Jet & Diesel ~ 37%

Gasoline ~ 49%

LPG ~ 3%

Refined WTI CrudeDistilled WTI Crude

Volume Gain ~ 6%

The Refining Barrel

42 Gallons

~50%

~50% ~90%

Not all crude oils are created equal…

Lots of asphalt! No asphalt!

Crude oil properties control asphalt quality!

Source: US Energy Information Administration

More Asphalt

Source: Tom Shetina, HFC

FCC

Unit

Diesel

Hydrotreater

Alkylation

Unit

Hydrotreater Isomerization

Unit

FCC Gasoline

Hydrotreater

Atm

os

ph

eri

c D

isti

lla

tio

n

Va

cc

um

D

isti

llati

on

Coker PDA Pitch

Gas Oil

Diesel

Jet Fuel

Kerosene

Hydrotreater Heavy

Naphtha

Catalytic

Reformer Sweet

Naphtha Reformate

Light

Naphtha

Merox

Treater

Isomerate

Vacuum

Resid

Atm

osp

he

ric

Bo

tto

ms

Asphalt or Fuel Oil

FCC

Hydrotreater

Gas Oil

Hydrocracker

Heavy

Gas Oil

Light

Gas Oil

Gasoline

Jet Fuel

FCC Gas Oil

Petroleum Coke

Gas

Processing

Merox

Treater Propane

Butane

Amine

Treater

Refinery Fuel Gas

Claus Sulfur

Plant Sulfur

Diesel

Hydrocracked Gasoline

Distillate

Isobutane

Olefins

Fuel Oil

Other Gasses

Gas Oil

Naphtha (after hydrotreating)

Gas H2 Gas H2

Gas H2

Gas H2

Gas H2

(or NHT then Cat Reformer)

Light Cycle Oil

Gaso

lin

e B

len

din

g

High RVP Season

Alkylate

Treated Gasoline

Gas H2

Gas H2

Gas

Gas

Gas H2

So

ur

H2O

Str

ipp

er

Steam

Sour

Waters

Stripped

Water

H2S and NH#

to Sulfur Plant

Crude

Oil

Complex/Integrated Refinery

Refinery Processes That Make Asphalt

Separation

Atmospheric distillation

Vacuum distillation

Solvent Deasphalting Unit (SDA, PDA)

ROSE and other HCC Units

Conversion

Oxidizer

Coker, FCC, etc. – NOT!!

Feed Pitch

Viscosity Test and Spec (1970s – 1990s)

Grades: AASHTO M226

AC 2.5, AC 5, AC 10,

AC 20, AC 30, AC 40

Do this at 140 F

plus some other

tests.

Kinematic (275 F) Absolute (140 F)

Viscosity Specifications

Advantages

viscosity is a more fundamental test

characterizing asphalt over wider range of temperatures

control of temperature susceptibility

Disadvantages

did not work well with modified asphalts (fact vs perception?)

bad timing?

something missing?

Bad Timing???

Winnie, Texas, 1981

TRB Special Report 202 – America’s Highways: Accelerating the Search For Innovation (1984) “… the procurement process for asphalt began more than 70 years ago…this process does not accommodate improved adhesion, wetting, and oxidation characteristics…the current knowledge of such desireable properties… is not sufficient to be able to incorporate them in a procurement specification.”

Something missing???

NCHRP Report 269, Paving with Asphalt Cements Produced in the 1980s, Epps, Button, and Gallaway, 1984 “The physical properties of asphalt cements are…more variable…than 20 years ago, even though they remain within specification values; but variations in other factors may mask the influence of this variation on pavement performance.”

Where Did PG Come From? (It’s a relatively new thing! 1993 to present)

Strategic Highway Research Program

1987-1993

$50 million research project by state DOTs

primarily at universities

Product was called Superpave

Superior Performing Asphalt Pavements

PG binder spec with new tests

mix design system

Adopted throughout all of US by now

PG binder spec - AASHTO M320

mix design and analysis (no)

What’s this “PG” All About?

PG 64-22 High pavement temp (C)

to protect against rutting

Low pavement temp (C)

to protect against

thermal cracking

Another Way to Look at It

Testing binder to get

good performance for

this layer at expected

pavement temps.

Test asphalt binder at temps

this layer feels

(high, intermediate, low)

PG Physical Property Tests

Dynamic Shear Rheometer (high/med temp properties)

Bending Beam Rheometer (low temp properties)

PG Plus

Tests added to AASHTO M320 to ensure binder is polymer modified

elastic recovery

cold ductility

toughness and tenacity

force ductility

compatibility

others…

Other Stuff in Asphalt

• Inorganic acids (e.g., PPA)

• Polymers and attendant stuff

• Construction Enhancers (e.g., WMA additives)

• Waste Post Consumer Products (e.g., scrap tires, shingles)

• Fillers and Fibers

• Antistripping agents

• Hydrocarbons

• Antioxidants

• Extenders (e.g., REOB)

• Rejuvenators

Log Temperature

Log Log Stiffness, Viscosity, etc.

Unmodified

polymer modified

Modification via polymer

Types of Polymers

• Elastic Type

- SB diblock

- SBS

- SBR latex

- Waste rubber

• Plastic Type

- EVA

- polyethylene

Polymer Modified Asphalt (Elastic)

Advantages

Significant performance history

Elastic effect

Improved cohesion t = s tan (f) + c

Many specs designed around stretchy polymers (no mysteries)

Favorable co-modifier with others (e.g., PPA)

Disadvangates Can be challenging to

manufacture Compatibility can be a

problem Tougher to handle Sometimes not heat stable Challenge to emulsify Sometimes supply/price

not stable Relatively expensive

0

5

10

15

20

25

30

35

40

1960 1970 1980 1990 2000 2010 2020

Mil

lio

ns o

f T

on

s S

old

Source: Asphalt Institute

Asphalt Usage in U.S. (1963-2015)

2017 (tons) 21.7 MM Total 18.7 MM Paving

The Future?

• Asphalt Manufacture • heavier, sour crude

• more blending to grade

• AASHTO M332 (new PG) • compliance vs stiffness of binder

• eliminate ER test?

• no more “bumping” of grades

• More PG+ • “Delta T cee” (DTc)

• better lab aging (hopefully)

• compatibility tests

The Future?

• Modified Binders

• ability to quantify effect on mix

• “HIMA”

• More incorporation of waste post consumer stuff

• Life Cycle Assessment

Thank you… come see me in Arizona some time!