When Full Depth Reclamation (FDR) is used as part of a pavement rehabilitation strategy, it is intended to eliminate existing pavement distress, reuse existing materials and to create a stronger, higher load-carrying base for the pavement. Pavements with significant surface and structural distress are good candidates for FDR; however, not all good candidates for FDR show significant surface distress. Deeper subgrade or base failure can be improved by FDR to improve structural capacity.
Pavements that have deep subgrade or drainage problems are candidates for FDR when additional work is undertaken to correct these deficiencies. The reclaimed material is typically moved to one side, the subgrade reworked or stabilized and the reclaimed material placed back on the prepared subgrade for further processing.
Similar to all construction operations, identification of buried utilities, abandoned rail or streetcar lines, manholes, valves and other castings must be undertaken prior to the start of FDR. A serious safety hazard can be created, and/or damage to equipment, if a buried utility is breached by the reclaimer, particularly if the buried utility is a high-pressure gas line. Abandoned buried utilities or obstacles within the treatment depth should be removed prior to FDR. Active utilities within the FDR treatment depth should be carefully marked. They can then be exposed and worked around by the FDR equipment or they can be lowered or relocated depending on specifics of the project.
Pavement distresses which can be corrected by FDR include:
FDR was originally limited to low to medium traffic volume roadways because there was no effective way to pulverize the thicker pavements usually found on high-volume roadways. However, with the newer/larger equipment available, greater depths can be obtained and FDR can be used on high traffic volume roadways, as well. There is no upper limit to roadway traffic volumes provided a pavement structural design is undertaken to account for future traffic and traffic control allows for diversion of traffic onto a pulverized or stabilized surface without damage. FDR has been successfully used of airfield pavements, interstate highways, heavy duty parking facilities and industrial yards.
Compared to removal and replacement, FDR generally has much less impact on traffic. If traffic must be maintained, one-half of the width can be treated while maintaining two-way traffic on the other half of the road with warning signs, lane demarcation devices, flaggers and/or pilot vehicles. On arterial streets, alternating outside/inside lane construction sequencing can be implemented.
There are no climate restrictions for full depth reclamation. FDR has been used successfully in all four climate zones, wet freeze, dry freeze, wet no freeze and dry no freeze. However, there are weather restrictions during construction. See Weather Requirements for more information.