Standard scope of work

The work includes:

• Pulverization of the existing asphalt pavement and, if needed, part of the granular base
• Recovery and in-place treatment of the recycled materials from the existing pavement
• Uniform integration of a stabilizing agent into the recycled mix
• Reprofiling, grading and compaction of the retreated layer
• Preparation of the recycled structure to receive an asphalt surfacing or for temporary traffic, as required by the project
• Any work required to correct weak or non-conforming zones before or during the work

The work must be carried out in accordance with the applicable standards, including in particular:

• ASTM D698 / D1557 – Proctor
• ASTM D1883 – CBR
• ASTM D5084 – Hydraulic conductivity
• ASTM C39 / C42 – Unconfined compressive strength (UCS)
• AASHTO T-324 – Hamburg Wheel Tracking
• Applicable provincial standards (CCDG)
• Project-specific plans and specifications

Before stabilization, the following operations must be carried out:

• Pulverization or milling of the existing asphalt pavement to the depth specified in the project
• In-place recycling of the asphalt and granular materials targeted by the design
• Preliminary shaping of the recycled material
• Verification of bearing capacity by proof-roll or equivalent method
• Identification, excavation and correction of weak zones, pumping or instability
• Adjustment of the recycled material's moisture to near the optimum compaction value

As an indication, the treatment depth may typically be in the order of 100 to 150 mm, or as per the adopted design.

• Mixing must be performed using a reclaimer or a soil stabilizer suited to asphalt-pavement recycling work
• The LL-TEQ™ agent must be integrated uniformly throughout the full treated thickness
• The mixing passes must ensure adequate pulverization of the existing asphalt material, homogeneous distribution of the stabilizer, a uniform texture and the absence of untreated zones
• Adjustment aggregates or fines may be added if required to improve the structure or correct the gradation of the recycled mix
• The final mix must show a homogeneous appearance in colour, texture and moisture

The recycled and stabilized material must be graded to re-establish the longitudinal profile, crown, cross-slopes and transitions.

• Compaction must be carried out immediately after mixing
• The compaction equipment must be suited to the material and site conditions
• The number of passes, the sequence and the compaction methods must achieve the density required by the project, namely a minimum of 95% of standard Proctor
• Particular attention must be paid to edges, joints and tie-ins

Depending on the project requirements:

• The recycled and stabilized layer may be kept as an improved base
• An asphalt surfacing may be applied after sufficient curing of the retreated layer
• A light surface treatment using LL-TEQ™ may be applied to stabilize the surface fines, seal voids, improve surface cohesion and limit water penetration before paving or during a transitional phase

• Light traffic may be permitted once the retreated surface is judged stable; as an indication, reopening to light traffic is possible as early as 12 hours, depending on the site and field conditions
• Full opening to service depends on weather conditions, moisture content and the development of stiffness in the recycled material
• As an indication, a curing period in the order of 24 to 72 hours may be required
• Sharp turns and aggressive manoeuvres must be avoided early in curing

The work must favour the reuse of the existing pavement materials in order to:

• reduce excavation
• limit off-site hauling
• decrease the use of new materials
• reduce the environmental impacts associated with conventional reconstruction

The available testing also shows that, under the conditions tested:

• the migration of contaminants into water is reduced
• water in contact with the treated materials shows no measurable toxicity

(reference: runoff testing – EPA-type protocols)

• The work applies specifically to existing asphalt pavements to be rehabilitated in place
• The treatment parameters must be adjusted according to the condition of the existing pavement, the nature of the recycled materials, the site conditions and the project requirements
• The acceptance criteria are defined in the project-specific specification, the plans and by the engineer of record

The process aims at:

• the structural rebuilding of an existing asphalt pavement by in-place recycling
• the improvement of the bearing capacity of the recycled material
• the reduction of permeability
• the improvement of durability against water and freeze/thaw
• the optimization of the reuse of existing materials
• the creation of a stable recycled base able to receive an asphalt surfacing or to serve as a transitional surface depending on the project

The work must be carried out in accordance with:

• recognized industry practices for in-place asphalt-pavement recycling
• the manufacturer's recommendations
• the applicable execution procedures (SOP)

The contractor must ensure that the crews master the retreatment, mixing, compaction and finishing methods related to the process.

This specification is intended for projects involving:

• rehabilitation of existing asphalt pavements
• in-place retreatment of municipal roads
• optimization of bases before asphalt surfacing
• work on main roads or other segments targeted by the project requirements

• Reduced reconstruction costs
• Reuse of existing materials
• Reduced hauling and use of new materials
• Improved structural performance
• Reduced environmental impacts associated with the work