CALAPA

SAN DIEGO TECHNICAL COMMITTEE MEETING

MAY 27, 2015

PRACTICAL ASPECTS OF USING AND MAKINGHIGH RAP HMA

STEVEN ESCOBAR & ROBERT STAUGAARD (APART, INC.)

What is a High RAP HMA?

Any HMA that contains ≥ 25w% RAP in the HMA or

Binder replacement of ≥ 20w% in the HMA.

Recommend to check consistency in the final HMA

even it contains ≤ 15w% RAP.

Will be talking about RAP HMA ≥ 40%

HIGH RAP HMA

HIGH RAP HMA

Key Factors for using high RAP HMA:

1. Need to determine the asphalt content and the

consistency of the aged binder in the RAP and each RAP fraction.

Determine the “True PG grade” of RAP Binder

HIGH RAP HMA

HIGH RAP HMA

Key Factors for using high RAP HMA:

2. Need to evaluate recycling agent to adjust consistency in aged RAP binder to meet PG Grade for climatic condition where the recycled pavement is placed.

Recycling Agents and/or soft asphalt cements.

HIGH RAP HMA

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

HIGH RAP HMA

HIGH RAP HMA

hRAP Properties:

h Similar geographic areas will have similar type of pavements based upon aggregate size & asphalt content and grade.

h Try to separate special RAP derived from crumbed rubber, polymer modified and other special pavements.

HIGH RAP HMA

gRAP Properties:

g 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.

PRODUCING THE FINAL ASPHALT MIXTURE Analyze each of the four

RAP crushed stockpiles for asphalt content and aggregate gradation.

Normally, about 8-10% new aggregate is needed to meet VMA requirement for the final mixture.

HIGH RAP HMA

Analyze all data and use data to meet end results specifications.

HIGH RAP HMA

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

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

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

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.

HIGH RAP HMA

Thank You!

Questions?