Construction Academy 2012 Asphalt Materials

Construction Academy 2012

Asphalt Materials

Tanya NashState Materials Office

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Topics

Asphalt OverviewAsphalt CQC (Specs 334 and 337)Miscellaneous Information,

Specification Changes, and Research

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Asphalt Overview

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12” Stabilized Subgrade

1” Friction Course

8” Base (Limerock or Asphalt)

4” Structural Course

Typical Asphalt Pavement Structure

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What is an Asphalt Mix?

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

Method of Design Hubbard Field (…

1960’s) Marshall (1960’s –

1998) Superpave (1998 ….)

Produced through an asphalt plant 5

Average Cost per Ton of Asphalt Mix

Asphalt Binders

“Binds” the aggregate together.Provides…..

the “glue.” lubrication for compaction. durability (resistance to cracking).

The most expensive part of an asphalt mix.

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FDOT Asphalt Binder Price Index (PG 67-22)

Crude Oil

Where does asphalt come from?

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How does crude get here?

Pipeline

Ship

Oil Refinery 11

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0 20 40 60 80 1000

200

400

600

800

1000

CRUDE OIL DISTILLATION (TYPICAL)

PERCENT DISTILLED

TEM

PER

ATU

RE

oF

GAS

GASOLINE

DIESEL

KEROSINE

GAS OIL

ASPHALT

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Superpave Asphalt Binders

Grading system based on climate

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PG 67-22

PerformanceGrade

Average 7-daymax pavementdesign temp

Min pavementdesign temp

Examples of PG Grading System

Florida: PG 67-22 (153°F to -8°F) Old 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)

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Typical Asphalt Binders (916) PG 67-22 – Standard Grade

<20% Reclaimed Asphalt Pavement (RAP) PG 64-22

20 – 29% RAP Recycling Agent (RA)

≥ 30% RAP PG 76-22

PG 67-22 base asphalt + SB or SBS Polymer ≤ 20% RAP

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Typical Asphalt Binders (916)

Asphalt Rubber Binders ARB-5 - Dense graded friction course (≤

20% RAP). ARB-12 - Open graded friction course (no

RAP). ARB-20 - Asphalt Rubber Membrane

Interlayer (ARMI). No Rap allowed.

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Typical FL Mix TypesStructural Courses (334)

Superpave SP-9.5, SP-12.5, SP-19.0

Friction Courses (337) FC-9.5, FC-12.5, FC-5 (OGFC)

Base Courses (234) B-12.5

Other Asphalt Treated Permeable Base

(ATPB)▪ Used under PCC pavements

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Superpave - Structural (334)

Purpose: Load carrying portion of pavement Superpave Mix Design

Three mixes based on max 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

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15,000 lb0.48 ESAL

6,000 lb0.01 ESAL+ =

34,000 lb

1.10

34,000 lb

1.10+ =

12,000lb

0.20+

0.49 ESALs

ESAL Examples

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2.40 ESALs

Mix Design Traffic Levels

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Traffic Level ESAL’s

A < 300,000 ESAL’s

B 300,000 < 3 million ESAL’s

C 3 million < 10 million ESAL’s

D 10 million < 30 million ESAL’s

E ≥ 30 million ESAL’s

ESALS come from

planning

Traffic Levels are found in

the Contract

Traffic Distribution for State Roads

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1%

40%

37%

19%3%

TL-ATL-BTL-CTL-DTL-E

C

DB

Gradation Types

Coarse mixes – More coarse aggregate than fine Higher density requirement Greater likelihood of being permeable Placed thicker Tough workability

Fine mixes – More fine aggregate than coarse Similar to old FDOT Type S mixes

Shown on the mix design25

Fine graded SP-12.5 mix27

Coarse graded SP-19.0 mix28

Friction Courses (337) Purpose: Provide a pavement surface

with good tire/pavement friction. Required on all jobs with:

Design Speed ≥35 mph, except rural 2-lane roads with 5-yr projected AADT of ≤3,000.

Use polish resistant aggregate Oolitic limestone (Dade & Broward Counties) Granite (Georgia & Canada) Siliceous Wackestone (Canada) Shell rock (Palm Beach Co.)

Use asphalt rubber binder (ARB) or PG76-22.

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Fine Graded Friction Courses

Good microtexture▪ Function of the aggregate

Superpave mixes:▪ FC-9.5 (1” thick)▪ FC-12.5 (1 ½” thick)▪ Formerly called FC-6

100% oolite or 60% granite▪ If granite, then can contain 20% RAP, otherwise

no RAP.

ARB-5 or PG 76-22 depending on traffic level.

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Open-Graded Friction Courses

Required on high speed multi-lane facilities.▪ Design Speed ≥ 50 mph

Good macrotexture.▪ Minimize hydroplaning.

FC-5 (3/4” to 7/8” thick) 100% friction approved aggregate (No

RAP). ARB-12 or PG76-22. Stabilizing fibers (more asphalt, less

draindown). Granite aggregate requires hydrated

lime.31

FC-5 Nassau County

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Close-up FC-5 Macrotexture 33

Base Courses (234)

B-12.5Superpave Mix

Traffic Level BMay substitute an SP-12.5

It’s basically the same mix!

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Questions/ Comments?

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