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Applications  > Ultra-thin Whitetopping
Pavement repair
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Whitetopping is a portland cement concrete overlay on existing asphalt concrete pavement. It can be used as a road surface course where traditional paving materials have failed due to rutting or general deterioration.

There are three types of whitetopping:
 
  • Conventional (thickness greater than 8 inches)
  • Thin (thicknesses over 4 but less than 8 inches.)
  • Ultra-thin – (2 to 4 inches) Ultra-thin whitetopping (UTW) is a bonded, fiber reinforced concrete overlay.
uses

 

This rehabilitation option has been used for many years on airport pavements, highways, secondary roads, and other pavements.

why
Whitetopping offers:
 
 
  • Improved performance -- no rutting or washboarding
  • Ability to maintain surface grade – many installers mill off the amount of asphalt that will be replaced by the UTW so that they don’t change the surface grade
  • Competitive price with other resurfacing methods
Sustainability
Whitetopping contributes to sustainable solutions by:
 
Cool. Concrete's higher albedo reduces heat islands.  If part of a project site may contribute to LEED Credit SS 7.

Minimizes waste.  Less material to landfill – most of the existing, worn asphalt pavement serves as a base for the concrete, thus eliminating the need and expense to tear up and haul away the asphalt

considerations
ultra thin pavement repairBase: Most of the existing, worn asphalt pavement is left in place and serves as a base. Ruts in the asphalt are milled down to start with a clean level surface. Ultra-thin whitetopping (UTW) should not be placed over asphalt pavement that shows signs of deep pavement distress. If potholes, alligator cracking, or deep fissures exist in the asphalt, the concrete will not form an adequate bond, resulting in pavement that lacks adequate support. Asphalt pavement should be at least 3-inches thick to provide a sufficient base for UTW. Many installers mill off the amount that will be replaced by the UTW so that they don’t change the surface grade. Whitetopping can be placed using conventional paving equipment.
 
Joints: Joint spacing is critical to a good performing UTW project. Successful projects use a short joint spacing to form, in effect, a mini-block paver system. Experience indicates that joint spacings should be no more than 12 to 18 inches each way per inch of whitetopping thickness. For example, a 3-inch UTW surface should be jointed into 3x 3 or 4x4 foot squares. Joints are sawed early to control surface cracking.

BOOKMARK
Resources
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Located at BookstoreAccelerated Pavement Testing to Evaluate UTW Load-Carrying Capacity
This special report describes the accelerated pavement testing of ultra-thin whitetopping (UTW) undertaken by the Federal Highway Administration at their accelerated loading facility (ALF) in McLean, Virginia. The UTW pavement sections were placed in 1998 atop existing asphalt sections that had been previously loaded by the ALF. The eight pavement sections were loaded by the facility, and five of the eight lanes showed little or no distress as a result. Conclusions indicate that the load carrying capacity of UTW is sufficient for its intended uses, including streets, local roadways, general aviation pavements, bus lanes, turning lanes, and ramps.
Located at BookstorePortland Cement Concrete Overlays - State of the Technology Synthesis (2002)
American Concrete Pavement Association, Product Code SP045P, 188 pages
Available for $5. Link goes to bookstore page, search by product code. This report, produced by the Federal Highway Administration (FHWA), presents the latest information on the design, construction, and performance of portland cement concrete (PCC) overlays. Bonded, unbonded, whitetopping, and ultra-thin whitetopping overlays are covered in this synthesis of the current state of the technology. This comprehensive book is a must-have for those interested in concrete pavement overlay design and construction.
Located at BookstoreRepair of Ultra-thin Whitetopping (2000)
American Concrete Pavement Association, Product Code PA397P, 4 pages
This document is available for $6 from American Concrete Pavement Association, search by product code at bookstore. This semi-technical brochure outlines the requirements and steps to repairing ultra-thin whitetopping overlays. Full-color photographs visually demonstrate each step.
Located at BookstoreWhitetopping State of the Practice
American Concrete Pavement Association, Product code EB210P, 70 pages
This document is available for $25 from the American Concrete Pavement Association, search by product code. Best-selling engineering manual includes comprehensive coverage of all aspects of concrete overlays on existing asphalt pavement. It includes information on the benefits, history, performance, design practices, and construction of all types of whitetopping. A special chapter discusses Ultra-Thin Whitetopping (UTW), including an interim procedure for determining the load-carrying capacity of UTW based on research and performance surveys.
Download DocumentSample specification for Ultra-thin Whitetopping (2000)
Ohio DOT Supplemental Specification 852 for UTW
Download DocumentUnique Whitetopping Approach Offers Strength and Durability in Wyoming (2004)
Portland Cement Association, #PL612, 2 pages
Available for free. This 2-page case study highlights the reconstruction of a deteriorated asphalt street in Sheridan, WY. The process included the use of full-depth reclamation (FDR) with cement for the base and ultra-thin whitetoppping (UTW) for the surface. Pavement design called for 3-1/2 inches of UTW with control joints sawn in a four-foot grid over eight inches of an FDR base. Tests performed after construction showed the cement-stabilized FDR base with a 28-day compressive strength of 320 psi and a 28-day concrete compressive strength of 5,250 psi. After a year of traffic, the reconstructed street is performing well, and the city is pleased with the results.
Located at External Web SiteNational Ready Mixed Concrete Association
Industry resource for ready mixed concrete.
Located at External Web SiteSolar Reflectance of Concretes for LEED Sustainable Sites Credit: Heat Island Effect
by Medgar L. Marceau and Martha G. VanGeem
This report presents the results of solar reflectance testing on 135 concrete specimens from 45 concrete mixes, representing a broad range of concretes. This testing determined which combinations of concrete constituents meet the solar reflectance index requirements in the Leadership in Energy and Environmental Design for New Construction (LEED-NC) Sustainable Sites credit for reducing the heat island effect. All concretes in this study had average solar reflectances of at least 0.30 (corresponding to an SRI of at least 29), and therefore meet the requirements of LEED-NC SS 7.1. These concretes also meet the requirements for steep-sloped roofs in LEED-NC SS 7.2. The lowest solar reflectances were from concretes composed of dark gray fly ash. The solar reflectance of the cement had more effect on the solar reflectance of the concrete than any other constituent material. The solar reflectance of the supplementary cementitious material had the second greatest effect.