tanya nash state materials office 1. asphalt overview asphalt cqc (specs 334 and 337) ...
TRANSCRIPT
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
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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
TE
MP
ER
AT
UR
E
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 Types
Structural 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
B300,000 < 3 million
ESAL’s
C3 million < 10 million
ESAL’s
D10 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
D
B
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 design 25
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. 30
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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