Lightly Surfaced Roads .

Chuck Jahren and Francis Dayamba

Photo taken by Francis O Dayamba

Motivation

http://www.roadscience.net/services/distress-guide/fatigue-cracking-alligator-cracking

http://www.roadex.org/index.php/permanent7

Presentation Outline

 Define Light Surface Treatment  Important Factors for success in applying Light

Surface Treatments  Outline of treatments discussed in presentation  LRRB County Engineer Survey  How to strengthen Subgrade/Subbase?  LST applied in other regions of the world  Alternative to Light Surface Treatment  Future Activities  Questions and Comments

Define Light Surface Treatment

http://www.sciencedirect.com/science/article/pii/S0921344901000672

Definition: A thin surface treatment of liquid asphalt covered with an aggregate that has an applied thickness of about 0.5-inch or less. -WSDOT

Important Factors for success

 Quality of Subgrade and Subbase  Experience of contractor  Quality of centerline joint and intersections  Appropriateness of geometry and pavement

markings

Outline of treatments discussed in presentation

Strengthening of Base  Fly Ash  Calcium Chloride and

Magnesium Chloride  Macadam Stone/Iron-

Mining Products  Geogrids and

Geotextile  Proprietary Products

 Base One  Geocells

Light Surface Treatments and Alternatives  Chip Seal  Otta Seal  Slurry Seal  Cape Seal  RAS and RAP

LRRB County Engineer Survey

Number of Counties

Survey Results

8 Otta Seals

2 Chip Seals

23 None Applied

2 Magnesium Chloride

1 Permazyme

36 total Respondents

LRRB County Engineer Survey

Picture taken by Francis Dayamba Stillwater, MN

Otta Seal

Picture taken by Chuck Jahren Charles Overby and Francis Dayamba TRB, Washington D.C.

1999 Otta Seal Guide Norway-NPRA

LRRB County Engineer Survey

Chip Seal

Pavement Interactive Website “Bituminous surface Treatment”

How to strengthen Subgrade/Subbase?

 Fly Ash  Base One  Macadam Stone  Many Proprietary

Products

http://www.stabilisedpavements.com.au/projectM4.html

www.roadsbridges.com/team-effort

How to strengthen Subgrade/Subbase?

 CaCl2 and MgCl2  Geogrids and

Geotextiles

http://www.na.fs.fed.us/spfo/pubs/stewardship/accessroads/geotextiles.htm

http://www.tencate.com/TenCate/Geosynthetics/documents/Miragrid/PDS_Miragrid0207.pdf

How to strengthen Subgrade/Subbase?-Geocells

•  100% recycled plastic •  Benefits

•  Dust reduction •  Maintains gravel •  Can handle heavy equipment

•  Permeable •  Cost •  Reduced installation time

http://www.geoproducts.org/EnviroGrid-EGA20.aspx

LST applied in other regions of the world Cape Seal

 Chip Seal followed by a slurry/micro-surfacing  Alleviates cracking and provides smooth/hard-

wearing surface

http://www.cityofsalem.net/Departments/PublicWorks/TransportationServices/Street%20Maintenance/Pages/CapeSeal.aspx

LST applied in other regions of the world Sand Seal

•  Emulsion followed by two layers(1/4”-1/2”) of sand/fine(3/8”) aggregate

•  Uses •  On top of Subgrade •  On top of Chip Seal/Otta Seal

•  Useful for areas with low supply of stone aggregate and high sand/fine aggregate

•  Limited ADT

http://repository.up.ac.za/bitstream/handle/2263/7879/108.pdf?sequence=1

LST applied in other regions of the world Macadam/Iron Mining By-Products

 Compacted layer(s) of large stone (Max 4”)  Seal Coat on surface  Hauling more than 20 miles(uneconomical in Iowa)

http://www.iowadot.gov/operationsresearch/reports/reports_pdf/hr_and_tr/reports/hr175.pdf

Alternative to LST-RAS and RAP

 FDR, In-place Recycling, Cold-Mix Asphalt and Hot-Mix Asphalt

 Sustainability  Cost effective  Reduces dust and surface distresses*

*Study by University of Wyoming Department of Civil and Environmental Engineering

http://cait.rutgers.edu/prp/updates-features

Future Activities

 Life Cycle Cost Analysis  GIS Project  Pavement Design

GIS County Map of Minnesota-MnDoT

Conclusions

 Many Alternative Light Surface options exist  Big Toolbox, choose the right tool for your

application, consider:  Available materials and pricing  Local Environment conditions  Structural Support

 Must be applied properly  Requires more investment in comparison to gravel  But can result in:

 Better road user and stakeholder satisfaction  Reduced ongoing maintenance costs compared to gravel

THANK YOU!

Questions?