This document provides an overview of S.T.A.T.E. Testing's perspective on hot mix asphalt technologies from their base in Illinois. It discusses their team and experience working with various agencies. The bulk of the document outlines sustainable HMA technologies like warm mix asphalt, recycled asphalt pavement, ground tire rubber, and recycled asphalt shingles. It provides details on mix designs and performance testing of projects utilizing these technologies, including a Tollway WMA project, a CDOT low ESAL surface mix, a friction course, and the Michigan Avenue SMA project in Chicago.
2. Jay Behnke, P.E.
President
S.T.A.T.E. Testing, LLC
Dundee and Chicago, IL
Behnke Materials Engineering
Beloit, WI
2
An HMA Perspective from the Land of
Gangsters and Cheese
11. 11
How to Change NDESIGN
1. Aggregate Structure
• More Coarse Aggregate
• More Manufactured Sand
• Less Natural Sand
• Less dust
2. Asphalt Binder Content.
12. 12
VMA – Voids in Mineral
Aggregate
“Space between the Rocks filled
with Asphalt Binder and Air
Voids”
Excludes Binder Absorbed into
the Aggregate
Sets Minimum Binder Content for
Durability
Varies with Aggregate Size.
14. 14
Aggregate Surface Area
One inch dia. rock makes 64 - ¼ in.
rocks
Sum of the ¼ in. rocks have 4X
surface area.
15. 15
VMA Spec by Aggregate Size
Nom. Max.
Agg. Size
Minimum
VMA
Air
Voids
Effective
Binder
9.5 mm 15 % - 4% = 11%
12.5 mm 14 % - 4% = 10%
19.0 mm 13 % - 4% = 9%
25.0 mm 12 % - 4% = 8%
16. Field VMA
Gmb
Dust to AC ratio
Contractor is
allowed to
remove dust
during production
16
17. 17
Field VMA: (f) % AC and Voids
Just a calculation – Uses existing
values
= 100 – (GMB * PS / GSB)
GMB: “d” from plant test
PS: % Stone = 100- %AC
GSB: Stone Specific Gravity from Design
e.g. = 100 – (2.415 * 0.94 / 2.687) = 15.5
Watch: If AC & Voids drop below mix
design values.
24. 24
When to Modify?
Extreme Temperatures
•Hot or Cold
Heavy Traffic
•Especially Slow or Stopped
Rutting or Shoving Problem Areas
Concern re: Reflective Cracking
Improve Film Thickness.
30. 30
RAP Can Be Our Friend
Quality
Green
Economical.
31. 31
RAP Works
Processed
Reasonable
Proportions
Designed into
the mix
< 20% - Acts as
“Black Rock.”
- Superpave Research
32. 32
Binder Grade for RAP Mixes
RAP% Binder Grade
≤ 20% Use Same PG Grade
> 20% Use Softer Grade
e.g. PG 58-28 for PG 64-22.
33. FRAP - Fractionated RAP
Old – RAP was bad
Then – RAP is OK
Now – FRAP is great
33
34. IL FRAP Sizes (typical)
34
< #4 (0.2 in.)
#4 to 1/2 in.
> 1/2 in.
35. Observations - FRAP
High Quality Grindings
Higher RAP % does not affect production
P#4 Material useful in SMA
• Angular
• Higher AC Content
Bids reflect overall savings
Less segregation
35
41. GTR is Versatile
Since 2006:
Green Alleys
City Streets (low
ESAL)
County Roads
(medium ESAL)
Tollway mainline
(high ESAL)
Bridge Decks
Michigan Avenue
41
42. WMA - Warm Mix Asphalt
Lowered emissions
Less fuel consumption
Worker health benefits
Lower temps = Reduced
oxidation
Extended paving season
• Haul time
• Compaction time
42
43. Warm Mix Technologies
Chemical additives, e.g.
Evotherm
Organic additives “wax”,
e.g. Sasobit
Foaming –Astec Double
Barrel® Green
43
44. CDOT Warm Mix Asphalt
6000+/- tons
Produced @ 230˚ F
Placed down to 180˚ F
Same rolling pattern
No difference in
workability
Reduced odor, fumes
48. RAS = Quality HMA Ingredient
Consistent gradation:
• 100% < 3/8 in.
• 93% < #4
30+% High Quality Fine Aggregate
26.4% High Quality AC
27.8% Mineral Filler
• Shoot for 1:1 ratio (dust to AC)
Mineral/Organic Fibers
48
61. CDOT manages a lot of Asphalt
Paving…in a variety of locations
61
62. CDOT by the Numbers
$600-800 Million Annual Budget
(More than half from state or federal grants)
262 bridges and viaducts
4,091 miles of streets (excluding Expressways)
26,658 intersections (2,935 signalized)
10,646,110 feet of lane striping
12,145 bike racks
10,997 trees planted/year
59 stations and 50 miles of track owned by CDOT but
operated by CTA
63. CDOT Typical In-House Program
2 Block increments
4 Paving crews
• 2 street / 2 alley
+/- 150,000 tons / year
placed
Innovative mixture(s)
Purchased from local
plants
Rented equipment
63
66. 4.75mm Friction Surface
Not a “sand mix”
Historically a
polymer-modified
mix
RAS used as
modifier.
Can be laid ¾”
thick!!
66
HMA version of Micro Surfacing
68. 4.75mm Friction Surface
New Specification
68
AGGREGATES PERCENTAGE
Natural Sand 40% Maximum
Manufactured Sand
15% Minimum
combinedManufactured Sand from Gravel;
or Steel Slag
Passing #4 portion of FRAP from
Steel Slag RAP; or Steel Slag 35% Minimum
combinedFine Aggregate from Steel Slag
RAP; or Steel Slag
RAS 7.5% Maximum
69. 4.75mm Friction Surface
New Specification
VOLUMETRICS
NDES = 50
Voids = 3.5%
VMA = 18.5%
69
ABR PG Binder Max. RAS
0-22% PG 64-22 2.5%
23-45% PG 58-28 5.0%
46-67% PG 46-34 7.5%
High ABR
70. 4.75mm High ABR Surface
2011 Demonstration
%
MIX
AC
Content ABR
FRAP (1) 8% 4.8% 0.4%
FRAP (2) 30% 5.8% 1.7%
RAS 7.0% 26% 1.8%
3.9%
Design AC 8.0%
New AC 4.1%
AC Savings $28 / Ton
70
About me…….QA Consultant for CDOT since ________________Thank for the opportunity to ……………………
About me…….QA Consultant for CDOT since ________________Thank for the opportunity to ……………………
Who we are:Chicago, O’Hareseveral large countiesIL Tollway
Contractors on Tollway projects paved over ¾ of a million tons of warm mix in 2012. 300,000 tons of SMAOver 200,000 tons each of shoulder binder and shoulder surface.The Tollway specification does allow contractors to request a waiver from the use of warm-mix for small tonnage placements, and items like patching did not require the use of warm-mix. So, there was some hot-mix placed this year, but it was less than 5 percent of the total tonnage on the reconstruction projects..