1. Barriers to Implementation of In-Place Recycling
NRRA Webinar
2/21/2017

2. Stabilization/Modifier Options
Cutbacks/Roadmix
Proprietary Products – many products & claims
Engineered Emulsion
Lime/chlorides
Foamed Asphalt
Flyash/Cement
Combinations of above

3. Full Depth Reclamation (SFDR) Keys to Success – Strength & Flex
Stabilization Considerations
Foam Asphalt or Lime
Cutbacks or Road Mix
Proprietary Products
Engineered Emulsion
Fly Ash or Cement
Prone to
Cracking
Prone to
Rutting
Stiff
Flexible
Organic
Clay
Granular

4. 1.5 - 3” SMA, OGFC or Superpave
APA Perpetual Pav’t }
” SMA, OGFC or Superpave 4” to 6”
Zone
Of High
Compression
High Modulus
Rut Resistant Material
(Varies As Needed)
Flexible Fatigue Resistant
Material 3 - 4”
Max Tensile Strain
This is the concept underlying the perpetual pavement.
Traffic stresses are highest near the surface of the pavement, so materials in the upper pavement layers must be resistant to rutting.
The intermediate or binder courses should be comprised of rut-resistant material. Materials which have worked well include large-stone mixtures or others which provide a strong stone skeleton.
Fatigue resistance is important in the lowest HMA layer or base layer. It is well documented that the most costly form of distress to fix in a pavement is bottom-up fatigue cracking.
The pavement foundation serves as the ultimate support for the structure during construction and service, so it must be considered an integral part of the pavement.
Pavement Foundation

5. } 1” UTBWC Flexible Fatigue Resistant Material 6 - 8”
2-3”
Zone
of High
Compression
High Modulus
Rut Resistant Material
Flexible Fatigue Resistant
Material 6 - 8”
Max Tensile Strain
This is the concept underlying the perpetual pavement.
Traffic stresses are highest near the surface of the pavement, so materials in the upper pavement layers must be resistant to rutting.
The intermediate or binder courses should be comprised of rut-resistant material. Materials which have worked well include large-stone mixtures or others which provide a strong stone skeleton.
Fatigue resistance is important in the lowest HMA layer or base layer. It is well documented that the most costly form of distress to fix in a pavement is bottom-up fatigue cracking.
The pavement foundation serves as the ultimate support for the structure during construction and service, so it must be considered an integral part of the pavement.
Pavement Foundation

6. Structural Benefit
The Stabilization process will increase the structural coefficient of the material
The structural coefficient of Stabilized material is dependent upon:
Stabilizing Material
Amount of P200 (fines)
Angularity of recycled material

7. Structural Coefficients, AASHTO example
Base Treatment
Existing Road Material
Very Dirty
Rounded Ag High Fines
Med Quality Ag Med. Fines
High Quality Ag High RAP
Untreated
< 0.10
≥ 0.14
Hydrated Lime
0.12
0.14
N/A
Cement (CTB) (soil cement)
(depends upon % cement & material; lower for less cracking)
Emulsion*
EE Granular Base Stabilization
EE Full Depth Reclamation
Foam*
0.25
CIR (EE)
HMA, NovaChip®
Coefficients depend upon:
Material quality
Passing the mix design criteria
Passing quality control requirements
* Values are from the literature. All values here generalized; each agency has own point of view.
Values validated by FWD
Nova 99 short.ppt

8. Recycle in Place What are some of the other barriers?
Paradigm Shift
Moving from “standard protocol” decision making
Agency Issues
Must be understood and accepted by all
Must be committed to by top management
Must have buy-in from Industry
Remove stigma that recycle is lower quality or “less value” than new construction
Industry Pressures
Introducing new technologies
Competition from industry (“rehab” and material suppliers)
Public Perception
Very positive once fully understood