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HOT-N-PLACE HOT SURFACE RECYCLING

1. Lab Testing ? General

Immediately after receiving a Notice to Proceed. The Contractor shall arrange for testing of the asphalt surface to determine the optimum type and quantity per unit area of recycling agent, and the density of the surface asphalt.  The Contractor shall request approval of a testing laboratory experienced in asphalt technology and receive approval from the Agency in writing before authorizing any testing.

1.1 Sampling

The Contractor shall instruct the testing laboratory to obtain cores at a minimum of four randomly selected points in the main travel lanes.  Each point shall be separated by not less than 1,000 feet (305m).  Half of the points shall be in one direction of travel and half in the other.  Core points shall be indicated on the contract plans and submitted to the Engineer with other test results.  Enough cores shall be taken to provide sufficient asphalt concrete to perform the necessary tests.

1.2 Test Methods

Extraction of asphalt shall be performed under Method ASTM D 2172 and shall be performed only on the top one inch of the core.  The extracted asphalt shall be reclaimed from solution by method ASTM D 1856.  Viscosity testing shall be performed under test method ASTM 2171 at 68 degrees C (140 degrees F).  Penetration shall be performed under test method ASTM D 5.

The testing laboratory shall provide optimal properties for the recycled asphalt.  A brief report of all test results and criteria used as basis for the selection of penetration and viscosity shall be submitted to the Engineer at lest two working days prior to the scheduled start of work.
 

A determination of density of the existing surface asphalt concrete shall be made in accordance with requirements of AASHTO T-245, with the exception that the compaction temperature of 260 degrees F.  This determination shall be made with the top one inch of asphalt in the cores.  The results of the determination shall be provided to the Engineer with the initial report for a recommended recycling agent.

The Contractor shall provide a one-pint sample of the recycling agent exactly as it will be sprayed during construction.  The Contractor shall deliver the sample to the laboratory that provided the recycling agent determination.

The testing laboratory shall test the sample to determine compliance with there recommendations.  The Contractor shall deliver subsequent samples until a sample is approved.  The Contractor shall instruct the testing laboratory to forward approval of the sample along with test results on the sample.  The test results shall include density of the diluted sample and the dilution ratio of the diluted sample.

All time required for testing, including the two days for Engineer review of the testing laboratory’s initial report for the recommended recycling agent, shall be included in the “Time for Completion” set forth in the General Specification of the contract documents.

All costs incurred for testing services required by the Subsection, shall be included in the bid item for heater scarification recycling.

2. Equipment

2.1 Heating Elements

The equipment used for the In-Place Hot Asphalt Surface Recycling shall perform as required by any and all of these specifications while fully meeting the standards of the local bureau of Air Pollution Control.

The heating system shall be 100% Radiant, with no flame greater than one inch away from the heating chamber surface, and shall have the capability to adjust the B.T.U. output from 40,000 to 100,000 evenly through each square foot of the heating chamber surface to allow uniform heating of the surface to be recycled and to adjust the temperature to various asphalt types and conditions.
There shall be a minimum of three heating elements utilized to heat the asphalt surface in all areas.

The heating system must also be capable to turn instant “ON and OFF” and to heat widths ranging from 2 feet to 13 feet depending on the widths that are being recycled.

2.2 Scarifier Unit

The scarifier unit shall include integral final heating element, scarification rakes, recycling agent system, mixing (secondary) rakes, reversible augurs, and heated vibratory screed.

The scarification rakes shall be designed such that the asphalt is displaced over the full heated area to the full-required depth.  These shall be in multiple rows and shall have spring-actuated pressure that is adjustable for equalization.  The scarifier teeth shall be designed is shape and adjusted in spring pressure in the field to provide purely viscous shearing of the heated asphalt.  The tooth design must provide uninterrupted scarification contiguous to ridged structures.

2.3 Recycling Agent System

The recycling agent system shall consist of a tank, spinner applicators, metering devise, including valves and actuators, and the other necessary regulators, hoses, pipes, valves and fittings.  The system shall provide an application uniform over the full width of scarification from 2 feet to 13 feet wide.  A hand spray system consisting of a hose reel, 50’ of hose and hose spray wand for tacking hand paced areas shall be provided on the unit, running off the some rejuvenator application system.  Hand pump, fruit sprayer type, systems will not be permitted.

The application shall be adjustable between .025 and .25 gallons per square yard to provide the specified amount of recycling agent per unit area.  The application shall be accurately metered by a device that continuously monitors the actual speed of the vehicle by direct mechanical means.

The metered application shall maintain a maximum tolerance of 10 percent form the specified volume per unit area at all speed ranges with automatic adjustment when speed change occurs.  Accurate monitoring of the applied agent must be easily accessible for the inspector without interrupting the operation.

The application of the agent shall be applied via spinning disc applicators, placing the material ahead of the second row of scarification rakes to displace the agent within full surface and depth of loosened material.  Spray applicators are not acceptable.

2.4 Spreading Device

Following the mixing teeth shall be a spreading device with augers and a screed with capabilities for crown adjustment, and depth controls are both extremities.  The augers shall be directionally reversible independently of each other.  The vibratory screed shall be heated with a thermostat control to maintain screed temperature between 275 and 325 degrees F and shall be equipped with adjustable end strike offs to move scarified material away from the gutter flags, adjustable from _” to 1 _” deep and from 3” to 18” wide.

2.5 Compaction

Following the leveling of the recycled asphalt it shall be compacted by means of a combination rubber/steel wheeled roller or a steel wheeled roller followed by a rubber-tired roller.  Each weighing a minimum of 5 tons.
 

3. Construction

3.1 Preparation
Prior to commencing heater/scarifying operations, the existing pavement shall be cleaned of all extraneous material.  Power brooming shall be supplemented, when necessary, by hand brooming until all deleterious material has been removed from the existing surface.

3.2 Heater/Scarifier Setup

A competent crew shall be provided.  The heater/scarifier unit, and other heating units if used, shall be brought to full operation at a constant speed with all machine adjustments set for continuous operation by the Contractor.  The heater/scarifier must be capable of heating the surface to the proper depth at a minimum travel rate of 15 feet F.P.M. under normal working conditions.  If additional pre-heaters are required, only the last heater/scarifier shall do the scarifying.

The Contractor shall immediately thereafter accompany the Engineer and provide all work necessary for access of the Engineer to verify proper equipment operation.  Specifically, side covers on the heaters shall be removed to allow viewing of the heating element.

The Contractor shall make any adjustments necessary to comply with the plans and specifications.  If following adjustments, the proper depth of penetration cannot be achieved, or performance of equipment does not conform to plan and specifications, the operation shall be terminated as directed by the Engineer.  The operation.  Any resumption of operation or change in speed is subject to the same preceding requirements as for the initial setup.

3.3 Heater/Scarifier Operation

Heater elements shall be adjusted to meet the minimum performance requirements of subsection (Equipment).  The heater/scarifier unit shall be operated at a constant speed, and the minimum weight per unit area of scarified material, based on density determined by testing performed under Subsection (Lab Testing) shall be continuously maintained.

The existing asphalt surface shall be heated from 6 to 12 inches wider than the width to be processed.

Surface asphalt concrete shall be loosened and displaced by the scarifying rakes through viscous shearing only.

The temperature of scarified material shall be a minimum of 250 degrees F and shall not exceed 350 degrees F when measured immediately behind the screed.

Crown adjustment, depth control adjustments. Auger directional settings and edger adjustments shall be made to provide a cross-section that conforms to the pavement profile specified.
 

Heater/scarified surface recycled materials shall be immediately compacted.  Where an overlay of new asphalt concrete is to be place immediately after surface recycling, rolling shall not be preformed on the recycled surface.  The new asphalt concrete shall be placed before the residual surface temperature falls below 180 degrees F.

If the new asphalt cannot be placed before the residual surface temperature falls below 190 degrees F, at that time it shall be rolled prior to the placing of the new material.

In all cases, asphalt concrete placed on the recycled surface shall be deposited, distributed and spread by a separate machine, independent and disconnected to the heater/scarifier unit, and shall be constructed in conformance with the standard practices.

When the recycled surface is exposed to traffic or left more than 24 hours after recycling, or where cleaning is required to remove foreign material or dust, a tack coat shall be provided in conformance with standard practices, or the cleaned surface could be brought back up to temperature of 190 degrees F by means of a pre-heater.

3.4 Paving

Immediately following the recycling operation and before the residual surface temperature falls below 180 degrees F, a layer of new asphalt concrete, as specified by the Engineer, is to be placed over the recycled surface at the rate of not less than 50 pounds per square yard and shall be performed according to standard practices in the industry for this area.

4. Measurement and Payment

In-Place hat asphalt surface recycled pavement will be paid for at the contract unit price per square yard.  Such price will constitute full compensation for finishing and placing of materials required to complete the surface recycling, including the application of the recycling agent, and re-compaction, and for all labor, equipment, tools, testing services and incidentals needed to complete the work in conformity with the Plans and specifications.

Measurements to determine the area to be paid for will be made in horizontal planes.

Recycling agent concentrate will be paid for at the Contract Unit price per gallon by certified weight.  The unit price shall include full compensation for furnishing and installing the recycling agent.

The new asphalt will be paid for at the Contract Unit price for each ton.  Such price shall constitute full compensation for furnishing all the necessary labor, materials, equipment, tools and incidental in conformity with the Plans and Specifications.

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