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RE-HEAT Asphalt Surface Recycling

Description. This work shall consist preparing the surface, heating the pavement, applying rejuvenating agent, mixing in heated drum mix plant, leveling, laying, and re-compacting the pavement surface in accordance with these specifications and details shown on the plan.

Materials. The asphalt-rejuvenating agent shall be composed of petroleum resin oil base, with a record of satisfactory service as an asphalt-rejuvenating agent. Satisfactory service is being based on the capability of the material to increase the ductility, penetration and durability of the asphalt binder in the recycled asphalt. A letter of compliance shall accompany each shipment delivered to the project from the manufacturer that certifies the material conforms to the manufacturer specifications.

Equipment. The recycling equipment unit used for collecting the existing asphalt concrete together, adding the new rejuvenating agent, mixing and paving the recycling mix in a continuous process shall be self-contained, self-propelled unit designed for this purpose.

The self-containment requirement for the recycling unit shall mean once the existing asphalt pavement is sheared, it remains contained in the recycling unit, and shall be immediately mixed with the rejuvenating agent. The recycled asphalt pavement shall not be exposed to atmospheric conditions except when placed for compaction.

The heating units shall be of sufficient capacity to heat the pavement material as necessary for efficient processing, but be designed as to minimize the damage to the asphalt binder. The heating system shall also have provisions for cooling the asphalt surface to 170° C (350°F).

The recycling unit shall be capable of loosening the heated asphalt pavement to the specified depth in a uniform pattern, loading existing asphalt and adding heated rejuvenator into a heated mixing plant for a minimum of 30 seconds. The recycling unit shall then be capable of placing and leveling the recycling asphalt pavement in a condition for immediate re-compaction. The rate of application of the rejuvenating agent shall be adjustable to maintain the appropriate application rate in the relation to the operating speed of the machine. Metering devices shall be incorporated into the distribution systems for recording the quantities of asphalt rejuvenating agent. The mixing shall take place in a heated rotating drum mix plant for at least 30 seconds in such a manner as to ensure complete blending. The recycling unit shall also have an adjustable, heated, vibratory screed capable of placing the mixture to the required cross-section, profile and alignment. Compaction equipment shall meet these applicable requirements.

Weather Limitations. The minimum surface temperature shall be 40°F and minimum air temperature shall be 50°F and rising.

Construction. The existing pavement shall be heated to allow for loosening of material without excessive fracturing of the aggregate and allow for adequate re-compacting. The pavement is then hot sheared to a nominal depth of 50 mm (2 inches) as measured by a depth probe behind the screed on a finished, un-compacted surface with an average of 3 depth probe checks across the width of the pavement.

Rejuvenator is applied in a uniform fashion and automated to the speed of the asphalt recycling machine. It is then mixed for a minimum of 30 seconds. On-board asphalt plant temperature must be maintained at a minimum of 300°F in order to establish an environment for maximum blending and coating. The newly recycled material shall be placed at the minimum temperature 225°F at the screed. Surface texture shall be uniform and consistent with no segregation or excessive asphalt cement.

Temperature processing limits shall be established. Exposure of the existing pavement to temperatures in excess of 350°F shall be limited to furnace heat transfer areas only. When necessary, methods of cooling the pavement surface temperature to below 350°F must be employed outside of the furnace condition.

Compaction shall be preformed in accordance with state and local specifications.