RATIONALIZING
RAP
RAP = GREEN
What does GREEN mean?
– Conserving our resources
– Reducing energy cost
– Reducing Greenhouse Emission
– Being more environmentally friendly
– And building a better, longer-lasting
pavement
UPHILL BATTLE
Maximizing
RAP Use
Barriers to increasing the use of
more Recycle
– Fear of making a mistake
– Meeting skid requirements
– Hardness of asphalt with high RAP need to use softer virgin asphalt
cement…fatigue cracking
– Special mixes like SMA
– Limit RAP to 15% when polymers
are used
Screen separates into
4 sizes
Single Cold Feed Bin
Sizing moved
back to the quarry
Expensive oil made RAP attractive.
Milling advancements made it easy.
Full-Lane Milling Machine
A VERY Brief History of RAP
Early RAP interest due to high cost of Trinidad Lake Asphalt
Oil in PA and TX in the 20’s (oil price plummets)
Planets lined up for RAP in the 1970’s
Screening Technology, 60’s and 70’s
Continuous Plants
1973 Oil Embargo
High AC Cost
Milling advancements, 1970’s
RAP becomes available
Continuous plants made RAP POSSIBLE.
High AC cost made RAP VALUABLE.
RAP availability makes it FEASIBLE.
6% Bitumen
30000 Tonnes of RAP
70 – 25700 liter tanker loads
And 28200 Tonnes of clean aggregate
RAP is worth the Virgin Material it Replaces
6% AC
30000 tons of RAP
70 – 6000 gallon tanker loads
And 28200 tons of clean aggregate
RAP is worth the Virgin Material it Replaces
Virgin Aggregate (per ton)
$25 X 0.94 = $23.50
Liquid Asphalt (per ton)
$350 X 0.06 = $21.00
Liquid Asphalt (per ton)
Virgin Cost:
Milling Cost (per ton)
$3.00
Trucking Cost (per ton)
Screening Cost (per ton)
TOTAL RAP COST (per ton)
$2.00
$3.00
$8.00
$44.50
$8.00
Difference
$36.50
10% RAP, $3.65/ mix ton savings,
10 tons to save total ∆ per ton
20% RAP, $7.30/ mix ton savings,
5 tons to save total ∆ per ton
50% RAP, $18.25/ mix ton savings,
2 tons to save total ∆ per ton
Savings: Virgin Materials vs. RAP (if RAP is purchased)
Reclaimed Asphalt Pavement
(RAP)
70% ½” minus
Milled and brought back to the plant “as is”
Lot’s of size variation
Potential for segregation in stockpile and when handled
RAP Pile With ½” (12.5mm) minus to ¾” (19mm) minus
6 to 8, North America
Reclaimed Asphalt Pavement
(RAP) Bin
Back to the 1920’s
Coldfeed Bins
Up to 16, Europe
Crusher Run
1980-1990’s HMA Facility with Single RAP Bin
RAP
½”(12.5mm) - 0
White Rock
3/8”(9.5mm) - #4
White Rock
#4-0
White Rock
½”(12.5mm) - 3/8”(9.5mm)
SUPERPAVE MIX
S
WITH ½ (12.5mm) minus RAP
½” (12.5mm) x 0
6% AC
½” (12.5mm) x #4
#4 x 0
3.5% AC
7.5% AC
It’s all about surface area!
48,000 ft² ( 4460 m²)
51,000 ft² ( 4738 m²)
Fine RAP (high AC)
Course RAP (low AC)
3/4” minus (19mm) RAP Bin
Course RAP (low AC)
Fine RAP (high AC)
1/2” minus (12.5mm) RAP Bin
So why is surface area important?
Course RAP
10
9
8
7
%AC 6
in 5
RAP 4
3
2
1
0
Fine RAP
7.5%
7.5
3.5%
3.5
-1/2, +1/4
-1/4
Gradation of RAP
Because RAP AC content varies with gradation, a variation in RAP
gradation due to segregation can affect overall AC content.
RAP Segregation can result in variation in overall AC content.
DONE
Example: RAP Segregation
10
9
We have input a correct AC percentage into the
computer -- but this RAP is segregated.
What will this
difference
cause?
7.5%
7.5
8
7
6
%AC i n
5
RAP
4
3.5
3.5%
3
2
1
0
20% RAP Mix:
0.2 x 7.5% AC = 1.5% AC
-1/2, +1/4
-1/4
Course
RAP
Fine
RAP
0.2 x 3.5% AC = 0.7% AC
1.5% - 0.7% = 0.8% AC swing
DONE
Example: RAP Segregation
10
9
We have input a correct AC percentage into the
computer -- but this RAP is segregated.
What will this
difference
cause?
7.5%
7.5
8
7
6
%AC i n
5
RAP
4
3.5
3.5%
3
2
1
0
40% RAP Mix:
0.4 x 7.5% AC = 3.0% AC
-1/2, +1/4
-1/4
Course
RAP
Fine
RAP
0.4 x 3.5% AC = 1.4% AC
3.0% - 1.4% = 1.6% AC swing
DONE
RUTTING
NO ONE WANTS TO PERPETUATE A
PROBLEM.
Rutting often occurs on older overlay
pavements.
End of Load Segregation
This is the processing
that ADDS VALUE.
RAP
Black Rock
½” (12.5mm) x 0
Black Rock
½” (12.5mm) - 3/8”(9.5mm)
Black Rock
#4 - 0
Black Rock
3/8” (9.5mm) - #4
PROCESSED RAP SCREENED TO ORIGINAL INGREDIENTS
ASPHALT BONDS BREAK MORE EASILY THAN THE ROCK.
White Rock
#4-0
White Rock
3/8” (9.5mm) - #4
White Rock
½” (12.5mm) - 3/8”(9.5mm)
Granite
Black Rock
#4-0
Black Rock
3/8”(9.5mm) - #4
Limestone
Black Rock
½”(12.5mm) –
3/8”(9.5mm)
Surface Mix
SUPERPAVE MIX
WITH PROCESSED RAP - CHOICE #1
White Rock
4-0
White Rock
3/8 - 4
White Rock
1/2 - 3/8
Virgin granite
SUPERPAVE MIX
Black Rock
4-0
Granite RAP
Black Rock
3/8 - 4
Black Rock
1/2 - 3/8
WITH PROCESSED RAP - CHOICE #2
White Rock
#4-0
White Rock
3/8”(9.5mm) - #4
White Rock
½”(12.5mm) - 3/8”(9.5mm)
Black Rock
#4-0
Black Rock
3/8”(9.5mm) - #4
Marshall
Granite virgin
Black Rock
#16-
Black Rock
#4-#16
Black Rock
½”(12mm)
- 3/8”(9.5mm)
Granite RAP
High 200’s
SUPERPAVE MIX
WITH PROCESSED RAP - CHOICE #3
Polymers SBS (How much is enough)
Aggregate in Mix-Uncrushed Gravel
Rut test performed on APA @ 147°F (64°C)
% Polymers
Rut depth
Cycles
0
12.5 mm
2,000
1
9.0 mm
8,000
2
8.0 mm
8,000
3
7.0 mm
8,000
4
6.5 mm
8,000
With RAP @ 50%...4% polymers in virgin liquid
results in 2% in final mix plus RAP liquid is harder
NCAT PAVEMENT TEST TRACK
1.7 miles
46 test sections
4 trucks, 3 trailers ea
20 hrs/day
2 yr = 15 yr
www.pavetrack.com
PLANT RAP FRACTIONATION
RAP STUDY MATS
N5-0%RAP-PG67
W3-20%RAPPG76
E5-45%RAPPG67
E6-45%RAPPG76
W4-20%RAPPG67
E7-45%RAPPG76s
W5-45%RAP-RA500
8/27/07 AVERAGE RUT DEPTHS
12
11
10
Average Rut Depth (mm)
9
8
7
6
5
4
3
2
1
0
N5-0%RAP-PG67
W3-20%RAP-PG76
W4-20%RAP-PG67
W5-45%RAP-RA500
E5-45%RAP-PG67
E6-45%RAP-PG76
E7-45%RAP-PG76s
Original Roadbed
After Overlay
After Traffic
Overlays Can Experience Cracks and Rerutting
Original Roadbed
After Milling
After Inlay
After Traffic
Milling and Inlays Prevent Rerutting
Sufficient Material for
Roll-down
Mix Contained
Mix Contained
No Segregation
Mix Contained
No Density Change
Milling Ensures Consistent Pavement Density
Milling Creates a Grooved Surface
Shoulder
Original Roadbed
Shoulder
After Milling
Shoulder
After Inlay
No Shoulder or Guardrail Changes with Milling
Overlays Change Bridge Clearances
Weight Limits Remain Constant with Milling
Multiple Overlays Create Drainage Problems
Milling Ensures Proper Drainage
Milling Leaves Utilities Unchanged
SUSTAINABILITY
Take Care of Your RAP and it Will
Take Care of YOU!
WMA
And
RAP
Go hand in hand.
Double Barrel Green®
Green®
Green Pac™
Pac™ Continuous
Green Pac™
Pac™ Batch
THANK YOU, AGAIN!