FULL DEPTH RECLAMATION (FDR)
Full depth reclamation is a process in which all of the asphalt pavement section and
a predetermined amount of underlying materials are treated with recycling agents to
produce a stabilized base course. Asphalt emulsions and/or chemical agents like fly
ash or Portland cement are added as recycling agents.
The main steps include pulverization, introduction of additive, shaping of the mixed
material, compaction, and application of wearing or surface course. This method of
recycling is normally performed to a depth of 100 to 300 mm (4 to 12 in)
Full depth reclamation has been recommended for pavements with deep rutting,
load-associated cracks, non-load associated thermal cracks, reflection cracks, and
pavements with maintenance patches such as spray, skin, pothole, and deep hot mix.
It is particularly recommended for pavements having a base or subgrade problem.
The major advantages and benefits of full depth reclamation are as follows:
The structure of the pavement can be improved significantly without changing
the geometry of the pavement and shoulder reconstruction.
It can restore old pavement to the desired profile, eliminate existing wheel ruts,
restore crown and slope, and eliminate potholes, irregularities, and rough areas.
Pavement widening operations can also be accommodated in the process. A
uniform pavement structure is obtained by this process.
It can eliminate alligator, transverse, longitudinal, and reflection cracking. Ride
quality can be improved.
Frost susceptibility may be improved.
The production cost is low, and only a thin overlay or chip seal surfacing is
required on most projects.
- Engineering costs are low
Materials and energy are conserved, and air quality problems resulting from
dust, fumes, and smoke are eliminated. The process is environmentally
desirable, since disposal problem is avoided.