Presentation delivered at the 2015 CalAPA Fall Asphalt Pavement Conference Oct. 28 in Sacramento, CA.

1. CALAPA
FALL ASPHALT PAVEMENT CONFERENCE &
EQUIPMENT EXPO
OCTOBER 28, 2015
PRACTICAL ASPECTS OF USING AND MAKING
HIGH RAP & RAS HMA
STEVEN ESCOBAR & ROBERT STAUGAARD (APART, INC.)

2. What is a High RAP HMA?
 Any HMA that contains ≥ 15w% RAP in the
HMA or
 Binder replacement of ≥ 12w% in the HMA.
Recommend to check consistency in the final HMA
even it contains ≤ 15w% RAP. Early cracking has
been
observed with RAP content in this range.
RAS should always be limited to 3-5% (dwa),
HIGH RAP HMA

3. HIGH RAP HMA

4. HIGH RAP HMA

5. Key Factors for using high RAP/RAS HMA:
1. Need to determine the asphalt content and the
consistency of the aged binder in the RAP/RAS
and
each RAP fraction.
 Determine the “True PG grade” of RAP/RAS
Binder.
HIGH RAP HMA

6. HIGH RAP HMA

7. Key Factors for using high RAP/RAS HMA:
2. Need to evaluate recycling agent to adjust consistency
in aged RAP/RAS binder to meet PG Grade for climatic
condition where the recycled pavement is placed.
3. Soft asphalt cement and/or Recycling Agents needs to
be evaluated.
4. For RAS a recycling agent is needed to adjust consistency but
RAS binder contribution will be limited. It is too stiff and needs plant
modifications to increase dwell and mixing times to make some
improvement in binder contribution but it will still be limited.
HIGH RAP HMA

8. Key Factors for making high RAP HMA:
3. Need to determine gradation of the recovered
aggregate in the RAP.
 Adjust new aggregate addition to
compensate for
any deficiencies.
HIGH RAP HMA

9. HIGH RAP HMA
RAP Properties:
Similar geographic
areas will have
similar type of
pavements based
upon aggregate size
& asphalt content
and grade.
Try to separate
special RAP derived
from crumbed
rubber, polymer
modified and other
special pavements.

10. HIGH RAP HMA
RAP Properties:
RAP Processing: To
gain more control on
aggregate gradation and
asphalt content in the final
mixture; the incoming RAP
must be screened into at
least four sizes, 3/4”x1/2”,
1/2”x 3/8”, 3/8”x 1/8” &
Fines. Only the oversized
RAP, greater than ¾”,
should be crushed to less
than ¾ ‘. These four
stockpiles of RAP have
definable asphalt content
and aggregate gradation
parameters which makes it
possible to adjust these
cuts to meet end-result
specifications on the final
recycled mixture.

11. HIGH RAP HMA

12.  PRODUCING THE FINAL
ASPHALT MIXTURE
 Analyze each of the four
RAP crushed stockpiles for
asphalt content and
aggregate gradation.
HIGH RAP HMA

13. HIGH RAP HMA

14. HIGH RAP HMA

15. Analyze all data and use data to meet job mix
specifications.
HIGH RAP HMA

16. HIGH RAP HMA
Tests Specifications
Min. Max.
Functions
Air Voids, % 3.0 6.0 Durability
Marshall
Stability,
Load, inch/lbs.
Flow, 0.01”
2,200
8
4,000
14
Mix Stability
VMA, % 13.0 -- Mix Stability
VFA, % 65 78 Mix Stability
Binder
Content, %w 4.8 7.5 Mix Stability
Recovered Aggregate Gradation, % Passing

17. HIGH RAP HMA
Sieve Size Specifications
Min. Max.
1” 100 --
¾” 100 --
½” 95 100
3/8” 72 88
#4 46 60
#8 28 42
#30 15 27
#50 10 20
#200 2 7

18.  Key Factors to Consider for Future
Hot-Mix Recycling Agents:
• Moving toward “Green” renewal
sources is good news. Just because it
is “Green” does not make it a suitable
product for this application.
• Check phase separation because of big
difference in specific gravities with
asphalt.
HIGH RAP HMA

19. HIGH RAP HMA
Key Factors to Consider for Future Hot-
Mix Recycling Agents:
• Check volatility (RTFO Oven) because
many of these products have results
≥ 15w%.
• Check flask point & thermal
degradation.
• Check for odor.

20. HIGH RAP HMA
Thank You!
Questions?