Construction Academy 2014

Construction Academy 2014

Florida Department ofTRANSPORTATION

Tanya NashState Materials Office

Florida Department of Transportation

• Asphalt 101• Asphalt Contractor Quality Control Process• Miscellaneous Information, Specification

Changes, and Research

Topics


ASPHALT 101

Ground Tire Rubber

Styrene-Butadiene-Styrene(SBS)

0

10

20

30

40

50

60

70

80

90

100

12.5 mm Superpave Gradation Chart

Sieve Size

Pe

rce

nt

Pa

ss

ing

#200

#100

#50

#30

#16

#8

#4

3/8"

1/2"

3/4"


• Blend of:– Asphalt binder (6%)– Aggregate (94%)

• Method of Design– Hubbard Field (…1970’s)– Marshall (1970’s-1998)– Superpave (1998…)

• Produced through an asphalt plant

What is an Asphalt Mix?

Aggregate stockpiles

RAP/RAS bin

Emission control system

Storage silo & load out

Liquid asphalt storage tank

Control

roomDrum

Dryer/Mixer

RAP/RAS stockpiles


SUPERPAVE

• SHRP (Strategic Highway Research Program): A $150 million research effort over a 5-year period approved by Congress;

– Started in 1987– $50 million spent on asphalt research;– Superpave “System” Delivered in 1993

• Final Product: Superpave (SUperior PERforming asphalt PAVEments).

– Developed to design asphalt pavements that will perform better under the extremes of temperature and loading.


Why did FDOT adopt Superpave?

• Existing Pavement Distresses– Rutting– Cracking (fatigue and

low temperature cracking)• Forecast for the Future

– Greater traffic– More trucks – Super Singles/Wide Based Tires


Superpave Mix Design

Select Materials• Binder• Aggregates

Design Aggregate Structure

Design Asphalt Binder

Content

Evaluate Moisture Sensitivity

Low Temperature cracking


Asphalt Binders• “Binds” the aggregate

together• Provides…

– the “glue”– lubrication for compaction– Durability (resistance to

cracking)

• The most expensive part of an asphalt mix

Aggregate• Stability, Constructability,

and moisture resistance– Consensus properties (fine

aggregate angularity, flat and elongated particles, and clay content)

– Source properties (toughness, soundness, and deleterious materials)

Materials


FDOT Asphalt Binder Price Index (PG 67-22)

$0

$100

$200

$300

$400

$500

$600

$700

$800


Crude Oil

Where Does Asphalt Come From?


How Does Crude Get Here?

Pipe

Ship


Oil Refinery


Fractional Distillation


Crude Oil Distillation (Typical)


• Grading system based on climate

PG 67-22

Superpave Asphalt Binders

PerformanceGrade

Average 7-daymax pavementdesign temp

Min pavementdesign temp


• Florida: PG 67-22 (153°F to -8°F)– AC -30 / 60 Pen– Actually PG 67-10

• Minnesota: PG 58-34 (136°F to -29°F)• Arizona: PG 70-10 (158°F to 14°F)

Examples of PG Grading System


Typical Asphalt Binders

Table 334-2Asphalt Binder Grade for Mixes Contains RAP

Percent RAP Asphalt Binder Grade

0 – 15 PG 67-22

16 – 30 PG 58-22

>30 PG 52-28

The bituminous material specification requirements are outlined in Section 916.


• PG 76-22 (PMA)– PG 67-22 base asphalt– Polymer Modified Asphalt (SB or SBS Polymer

• PG 76-22 (ARB)– PG 67-22 base asphalt– Minimum 7% ground tire rubber (GTR)– Polymer modification optional

• PG 82-22 (PMA)– PG 67-22 base asphalt– Polymer Modified Asphalt (SB or SBS Polymer)

Modified Asphalt Binders (916)



Average Cost per Ton of Asphalt Mix

$-

$20.00

$40.00

$60.00

$80.00

$100.00

$120.00

$44.19 $44.63 $49.13

$52.70 $58.33

$68.48

$91.52

$104.32 $98.21

$94.32

$82.79 $85.36

$91.19 $96.30


Typical Asphalt Pavement Structure

12” Stabilized Subgrade

1” Friction Course

8” Base (Limerock or Asphalt)

4” Structural Course


• Superpave Asphalt Concrete (334)– Structural asphalt mixtures– SP-9.5, SP-12.5, SP-19.0

• Asphalt Concrete Friction Courses (337)– FC-9.5, FC-12.5, FC-5 (OGFC)

• Superpave Asphalt Base (234)– B-12.5

• Asphalt Treated Permeable Base (ATPB) (287)– Used under PCC pavements

Florida Asphalt Mixtures


• Purpose: Load carrying portion of pavement– Superpave Mix Design

• Three mixes based on maximum aggregate sizes– 9.5 mm (SP-9.5)– 12.5 mm (SP-12.5)– 19.0 mm (SP-19.0)

• Five Traffic Levels (A-E)– Based on 18,000 lb. Equivalent Single Axle Loads (ESAL’s)– Low traffic = A, High traffic = E

• Concept: Put the right mix on the right road– Higher traffic level is not necessarily better

Superpave – Structural (334)


ESAL Examples

15,000 lb0.48 ESAL

6,000 lb0.01 ESAL+ =

34,000 lb1.10

34,000 lb1.10+ =

12,000lb0.20+

0.49 ESALs

2.40 ESALs


Mix Design Traffic Levels

Traffic Level ESAL’sA < 300,000 ESAL’sB 300,000 < 3 million ESAL’sC 3 million < 10 million ESAL’sD 10 million < 30 million ESAL’sE ≥ 30 million ESAL’s

Traffic Levels are found in the

Contract

ESALS come from

planning


A<300,000 ESAL’s

B300,000 to 3,000,000 ESAL’s

C3,000,000 to 10,000,000 ESAL’s

D10,000,000 to 30,000,000 ESAL’s

E>30,000,000 ESAL’s




Traffic Distribution for State Roads

1%

40%

37%

19%

3%TL-A

TL-B

TL-C

TL-D

TL-E


• Good microtexture– Function of the aggregate

• Superpave mixes:– FC-9.5– FC-12.5

• 100% Oolite or 60% Granite– If granite, then can contain 20% RAP, otherwise no RAP

• PG 76-22(ARB) or PG 76-22(PMA) depending on traffic level

Dense Graded Friction Courses (337 / 334)


• Required on high speed multi-lane facilities– Design Speed ≥ 50 mph

• Good macrotexture– Minimize hydroplaning

• 100% friction approved aggregate (No RAP)• PG 76-22(ARB) or PG 76-22(PMA)• Stabilizing fibers (more asphalt, less draindown)• Granite aggregate requires hydrated lime

Open-Graded Friction Courses (337)


FC-5 Nassau County


FC-5 MacrotextureFC-12.5 Microtexture


• 12.5 mm Superpave Mix– Traffic Level B– Paid by the square yard (285 – Optional Base)

Superpave Asphalt Base (234)


Questions/Comments?

Documents

Construction Academy 2014