New Tools Offer Better Guidance for Use of Concrete Overlays

TERRA – April 2014

Research at MnROAD has contributed significantly to the understanding of the field performance of thin and ultra-thin concrete overlays of existing asphalt pavement (also known as “whitetoppings”). The multistate pooled-fund project, which includes three TERRA members (Iowa, Minnesota, and New York DOTs), used data from MnROAD and other test sections to develop a rational design method for thin concrete overlays. In addition, a design guide developed through the project as a user-friendly web-based tool accommodates a variety of climate conditions, axle-load configurations, existing asphalt material conditions, and time-dependent bonding conditions between layers.

CP Tech Center also produced a broader guide about concrete overlays in 2012. The Guide to the Design of Concrete Overlays Using Existing Methodologies provides decision makers and practitioners with straightforward, simple guidance for the design of concrete overlays using existing methodologies. The guide focuses on four commonly used methods from AASHTO, ACPA, and the Colorado DOT. The guide, intended to be used in conjunction with the corresponding design procedures’ documentation/references, discusses specific design assumptions, deficiencies, and strengths inherent in each method, as well as step-by-step design examples for typical pavement sections.

Resources:

• BCOA-ME Design Guide
• Development of Design Guide for Thin and Ultrathin Concrete Overlays of Existing Asphalt Pavements [TPF-5(165)]
• MnROAD “whitetopping” project page
• Guide to the Design of Concrete Overlays Using Existing Methodologies (10.8 MB PDF, CPTech Center, 2012)
• CP Tech Center Concrete Overlays research page
• TERRA Concrete Overlays fact sheet