This document defines thin asphalt overlays as dense graded mixtures placed less than 1 1/2 in. in thickness. Thin asphalt overlays placed for pavement preservation are functional overlays to extend the service life of the pavement and are not intended to add structural capacity.
Sixteen sections were constructed on Aug. 20-22, 2019, as part of a partnership between City of Otsego, Minn., City of Albertville, Minn., and MnROAD as part of the MnROAD/NCAT pavement preservation study.
Pavement engineers have been producing long-lasting asphalt pavements since the 1930s. Research has shown that well-constructed and adequately designed flexible pavements can perform well for extended periods of time (Mahoney, 2001). Many of these pavements in the were the products of full-depth or deep strength asphalt pavement designs, and both design philosophies have been shown to provide adequate strength over extended life cycles (Newcomb et al, 2010).
All roads suffer from normal wear and tear on a daily basis. As a result, preservation treatments are regularly required to maintain these roads to meet the public’s travel needs. Thin asphalt overlays are one of many preservation treatments for roads that receive light to medium traffic volumes, and sometimes heavy traffic volumes.
The new APA document covers all the most important concepts, such as net present value, discount rates, salvage value, maintenance costs, and predicted performance life.
This technical publication provides useful guidelines to the pavement designers who deal with the challenges of intersections and other high-stress pavements.