Full-Depth Reclamation Process

Abstract

Many roads and streets fail structurally after having performed well for several years. The standby treatment of a hot-mix overlay does not address the real problem with most of these roads—inadequate roadbase strength. Public agencies throughout the United States are making fulldepth reclamation (FDR) one of the most popular pavement rehabilitation methods. The FDR process allows complete reconstruction using 100 percent of the existing pavement materials, while correcting grade, cross slope, and underlying pavement problems. In FDR a new base is produced by pulverizing the existing asphalt pavement and mixing it with some of the underlying granular materials. Additional structural strength can be achieved by incorporating new crushed aggregates, asphalt emulsion, foamed asphalt, and chemical stabilizers. Laboratory testing of the reclaimed asphalt pavement (RAP), the subgrade soils, and a mixture of the two will determine whether an additive is needed. The RAP testing should include an extraction for asphalt content and an aggregate sieve analysis. For soils, the minimum testing would include a sieve analysis, sand equivalent, liquid limit, plastic limit, and plasticity index. Guidelines for selecting stabilizers on the basis of these test results are included. Additional strength tests on the stabilized materials can be used in structural design of the pavement. A thorough project evaluation is essential to ensure success. This includes a pavement condition survey, a traffic study, and structural design, in addition to the testing. Proper construction procedures and quality control plus an experienced contractor are necessary.