Review of the Design and Performance of Sandwiched Pavements

About the report:

The studies reported herein concern one of the basic pavement design types used by the Virginia Department of Transportation for many years. Known as a sandwiched pavement design, the pavement consists of a relatively weak aggregate base layer between a strong, asphaltic concrete upper layer and a strong cement-treated stone or cement stabilized soil lower layer. Included in the studies were deflection analyses, performance evaluations, and the collection of aggregate base mechanical properties. The studies show that the sandwiched pavements generally do not perform as well as conventional pavements where layers grow successively weaker from the top to the bottom of the pavement. The life expectancy for sandwiched pavements was on the average two years shorter. Studies also showed that the deflection characteristics and therefore the performance of the sandwiched pavements is strongly influenced by the amount of minus 200 material in the aggregate base layer. A recommendation to management that the Department consider greater use of a graded aggregate base with no more than 8 percent minus 200 is included.

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