Mechanistic-Empirical Design Guide Modeling of Asphalt Emulsion Full-Depth Reclamation Mixes

Abstract

Full Depth Reclamation (FDR) using asphalt emulsion is a cost-effective method for rehabilitating distressed roads. A reclaimer mills through the asphalt layers and aggregate base, adds asphalt emulsion, and then mixes the materials. The uncompacted, recycled mixture is spread and compacted by motor graders and rollers. The new base can support traffic on the same day. Finally, a surface treatment or overlay is placed on the newly formed base. The FDR process adds strength and flexibility to the pavement structure, as well as removes distresses to improve future performance. Current pavement design methods do not account for the unique properties of FDR. These mixes behave somewhat similar to granular bases in their early life. After curing, the mixtures exhibit visco-elastic stiffness and performance-related properties similar to asphalt concrete. The mixture behavior depends on the stabilized materials and the properties of the asphalt emulsion with which they were stabilized. The asphalt emulsion used in this study is designed for returning the pavement to traffic on the same day as construction and for a quicker time to overlay compared to other emulsified asphalts. Two aggregate combinations were studied. One combination consisted of 25% reclaimed asphalt pavement (RAP) and 75% base rock. The other combination consisted of 75% RAP and 25% base rock. Cement was added to some of the mixtures. This paper discusses dynamic modulus testing performed on FDR mixes and how the test results relate to the expected performance in a pavement structure by the Mechanistic-Empirical Pavement Design Guide (MEPDG) software.