Full-Depth Reclamation Defined

FDR is an economical, in-place recycling alternative to road reconstruction. It uses a powerful reclaiming machine to turn an old asphalt pavement into a road base by uniformly pulverizing that full thickness of the old pavement and blending it with a portion of underlying material. This process usually adds bituminous emulsion, chemical or mechanical stabilization agents to enhance the strength of the new base that is sealed with an asphalt friction course or a sealing treatment, depending on expected loads. The process allows for correcting drainage and cross slope problems, as well as widening the roadway.

It makes sense when a pavement can’t be salvaged with milling, overlaying, or recycling techniques due to severe pavement defects, poor drainage, or an inadequate base.

It doesn’t make sense when the existing pavement can be preserved with lesser interventions.

How Does it Work?

Full depth reclamation is a process that offers economic advantages and design alternatives to pavement restoration. But how does it work?

The full-depth reclamation process revolves around the ability to pulverize and blend the deteriorated pavement structure to a specified maximum gradation and incorporate that material into the structural design of the restored roadway. Full depth reclamation offers several in-place alternatives to the designer in creating the desired roadway section. Read more about this process here.

Typical Applications

Full depth reclamation is most commonly used on secondary and farm-to-market roads, but the technology is increasingly being employed on higher-volume primary roads, too, including rural interstates.

Tricks of the Trade

Experienced FDR contractors and engineers use additives to create the ideal base. Bituminous emulsion additives are the most common, but they are often used in combination with chemical additives like lime, portland cement, and fly ash to add strength, as well as mechanical additives like crushed stone, RAP, and sand to correct deficiencies in the existing materials.

What it Costs

Full depth reclamation generally costs 30-50% less than traditional road reconstruction.

Full Depth Reclamation – The Design Process

 

 

Introduction

The design process for full depth reclamation can be split into three parts: the pulverization of the original surface and the blending of additives and/or imported materials, grading and compacting the new surface, and the application of a wearing surface. Read on to find out more about these steps!

 

STEP 1: Pulverizing and Blending

Pulverizing and blending is a mechanical process that physically breaks the pavement material to a usable gradation while incorporating a specified amount of existing base material. After this is completed, the process moves to the blending phase, where materials may be added that will help create the desired base. The percentages of additive are expressed as a percent of the weight of the material being mixed. Often during this stage, water will be added to the blend to ensure the mixing of material and additives is optimum.

But what happens when there isn’t enough surface to add to the blend? 

In this case, imported material to be incorporated into the base can be placed on the existing pavement prior to the mixing pass. After the mixing pass is completed, the base material is ready for shaping and compaction.

 

STEP 2: Grading and Compacting

Once the new blend has been laid, it is compacted and graded to the provided specifications. This process guarantees the mixture is properly formed to the road, and ensures a long lasting, durable surface.

STEP 3: Application of a Wearing Surface

Once the blend has been graded and compacted, a wearing surface is applied to the top of the blend, to ensure an even wear and longevity in road strength and durability. Though wearing surfaces vary, our reclamation process can implement most any wearing surfaces available.

It also may be necessary to apply a Fog Seal to the completed base. The Fog Seal will help control raveling and ensure a good bond between the base and the wearing course. In some cases, the Fog Seal may be sanded in order to open the road sooner to traffic. Contact us for this and other solutions for wearing surfaces today!

What is Typically Done in a Full Depth Reclamation Project?

 

 

Full depth reclamation can offer many alternatives to the restoration of a particular pavement. All or some combination of the following steps may be found on a full depth reclamation project:
•    Cleaning shoulders and ditches
•    Shaping and compacting pulverized material
•    Pulverizing the surface
•    Application and mixing of additives such as:

– Imported Material
– Water
– Asphalt Emulsion
– Cement
– Lime
– Calciium Chloride

•    Shaping and compaction of the treated base material
•    Application of a surface course

Advantages of Reclamation

 

Reclaiming is Economic

With reclamation, the hauling, heating and mixing costs associated with conventional maintenance techniques can be eliminated. Costs are also reduced, as the existing roadway material is reused. This can be hot mix asphalt, chip and seal, cold mix or simply gravel. Whatever the material, it’s already been paid for. Full depth reclamation stretches taxpayer dollars while improving driving conditions for the motoring public. And since the material is reused, typical disposal costs are reduced as well. Further, typical reclaimed roads can be thinner than roads using traditional construction methods, which results in less material per square mile.

Reclaiming is Environmentally Friendly

Since reclamation reuses materials, less material has to be disposed of. Reclaiming recycles this material, which also results in less new resources required, saving natural resources and energy.

Reclaiming is Efficient

Reclaimed roads are more resistant to frost penetration of the sub-grade, which reduces future maintenance. During the reclamation process, the roadway grade and cross-section can be modified in-process, resulting in quick construction times. And in emergencies, a road in process of reclamation can still be used by official vehicles. 

What’s more: our self-propelled reclaiming machine pulverizes the full flexible pavement section in-place. Modern reclaiming machines are designed to size the pulverized material for easy shaping and compaction. There’s no need to rip the road and load chunks into haul trucks. There’s no crushing and stockpiling. No return trip to the job site with crushed material. High quality base material is produced right on the job. And, it’s done consuming much less energy for additional cost-savings.

Reclaiming Standardizes Assorted Roadways

Full depth reclamation is designed to convert inadequate roadway sections into upgraded, homogenous base which will provide a stable platform for the appropriate pavement layer. The new base has the correct shape and proper compaction from shoulder to shoulder.

Reclaiming Lasts Longer

The expected service life of the reclaimed road before major maintenance is required is normally 50% longer than the lift of a road with frequent cracking which has been overlaid with a comparable HMA thickness. Cracking and rutting are substantially reduced on reclaimed roads and streets. Long term maintenance costs are less because the maintenance interval is extended. Today, many public work officials rely on full depth reclamation for the improved roads and streets and use the overlay method only on pavements with a sound foundation.

Limitations of Full Depth Reclamation

Thickness Requirements

Full depth reclamation is most often employed with pavements that are less than 12 inches thick.

Clearance Requirements

A full depth reclamation base topped with an asphalt overlay will reduce pavement clearances by the thickness of the overlay – unless the old pavement is pre-milled to the depth of the overlay.