(sample specifications)

2- STAGE HOT IN-PLACE RECYCLING OF ASPHALT PAVEMENT

DESCRIPTION

12.11 This work shall consist of 2-Stage Hot In-Place Recycling of the existing asphalt pavement to a nominal depth of 1.75 inches excluding areas of surface irregularities (i.e. cracking, rutting, shoving, both longitudinal and transverse depressions). The remixing method shall be a multi-step process of cleaning, heating, milling, adding recycling agent as specified in the contract, adding virgin Plant Mix Bituminous Pavement (PMBP) as specified in the contract, mixing, spreading, leveling and compacting the mixed material.

The work shall be accomplished by a single pass of an equipment train.

The Contractor shall furnish all equipment, tools, labor, materials (except the existing asphalt pavement), and any other appurtenances necessary to complete the work.

12.2 MATERIALS

12.21 Recycling Agents. The recycling agent added to the milled material shall be either an asphalt emulsion conforming to the requirements of AASHTO 140 or other petroleum products.

12.22 Additive Hot Mix. The admix shall conform to the requirements of the governing agency and shall have the same nominal maximum aggregate size and similar gradation to that in the recycled material.

12.23 Laboratory Analysis of Existing Pavement Material. The Contractor shall obtain representative samples of the in-place asphalt in a manner approved by the mix designer. The Contractor shall have an individual testing laboratory determine the following information:

For all samples:

Determine the overall sample thickness and individual layer thicknesses and material type. Divide the samples into reaches for grouping and determine the lengths or reaches of pavement of similar material type.

B. For Grouped samples:

Cut off top 2 in. of each sample for testing. Determine the bulk specific gravity of the top 2 in. portion. The aggregates and the binder from these samples are to then be separated by heating and a composite sample prepared by heating and mixing.

C. For Composite samples:

Determine the asphalt content and aggregate gradation of the composite samples and also determine maximum theoretical specific gravity. Mold three 4" diameter by 2 ½ " height specimens using any of the following three methods at a temperature determined by the mix designer.

1) Marshall Method: Follow AASHTO T 245 or relevant agency standard to mold the test specimens. Determine the number of required blows for the type of pavement and specific traffic conditions unless otherwise specified.

2) Superpave Gyratory Method: Follow AASHTO T 312 or relevant agency standard to mold the test specimens. Adjust the number of gyrations to 75 unless otherwise specified.

3) Hveem Method: Follow AASHTO T 247 or relevant agency standard to mold the test specimens. Determine the number of required tamping blows in the semi-compaction stage depending on the type of asphalt concrete.

Determine the relative strength of the three samples using one of the following two methods.

1) Marshall Method : Follow AASHTO T 245 or relevant agency standard to test the specimens. Determine the stability and flow characteristics of the asphalt concrete and compare with the appropriate project specifications or with industry standards.

2) Hveem Method : Follow AASHTO T 246 or relevant agency standard to test the specimens. Determine the stabilometer value of the asphalt concrete and compare with the appropriate project specifications or with industry standards.

D. If analysis shows that recycling agent and/or admix is needed, determine the following properties of the composite samples prepared at different recycling agent and/or admix addition rates.

1) Binder Content

2)Aggregate Gradation( if admix is used)

3)Maximum Theoretical Specific Gravity

4)Air Voids

5) Strength and Flow Characteristics( if appropriate)

E. Determine the amount of admix proportions to optimize the properties of the in-situ pavement.

12.3 CONSTRUCTION REQUIREMENTS.

12.31 Equipment.

12.311 General. The Contractor shall notify the Project Manager at the pre-construction conference of the type of equipment intended for use. The equipment shall be on the project in general operating condition in sufficient time for evaluation by the Project Manager.

12.312 Heating Units. The heating units shall be radiant heating devices capable of heating the existing asphalt pavement to a temperature high enough to allow milling of the material to the specified depth without breaking aggregate particles, without charring the existing asphalt, and without producing undesirable pollutants. The heating mechanism shall be so equipped that heat application shall be under an enclosed or shielded hood.

12.313 Milling Units. Two (2) individual Milling units (each capable of milling ½ the specified depth.) and up to twelve (12) feet in width shall be capable of loosening the in-place asphalt pavement to the specified depth without excessive breaking of the aggregate.

The units shall have sufficient power to mill through the high spots and create a leveled surface conforming to the plan finished profile of the pavement.

12.314 Recycling Agent/Additive Storage Unit(s). The storage unit(s) shall be thermostatically controlled to maintain the recycling agent/additive at a constant temperature as specified by the supplier.

12.315 Metering Unit(s). The unit(s) shall be capable of applying the recycling agent/additive in a uniform manner to the entire quantity of the milled material and shall incorporate a meter for continuous verification of quantities. The volume applied shall vary in direct proportion to the operating speed of the recycling system and shall be synchronized with the volume of material milled to maintain a tolerance within 10% of the specified rate. The recycling agent/additive shall be added to the milled material prior to the addition of Hot Mix.

12.316 Blending Unit. The unit shall be an independently powered twin shaft pugmill capable of thoroughly mixing the milled material, recycling agent/additive, and additive Hot Mix so as to produce a uniform, consistent final product.

12.317 Spreading and Leveling Unit. The unit shall be equipped with automatic grade controls. It shall be capable of spreading and leveling the blended and mixed recycled material uniformly and without segregation over the width being processed.

12.32 Construction Details.

12.321 Cleaning of Existing Pavement Surface. The existing pavement surface to be recycled shall be cleaned of all dirt, fabric, thermoplastic markers, rubberized materials, oils and other objectionable materials by blading, brooming, or other methods approved by the Project Manager prior to beginning hot in-place recycling.

12.323 Heating, Milling, and Processing. The in-place asphalt surface shall be evenly heated, milled, and processed to the widths and depths shown in the contract.

Heating shall be controlled to assure uniform heat penetration without causing differential softening of the pavement, without breaking of the aggregate particles, without charring of the asphalt, and without producing undesirable pollutants.

Recycling agent, if required, shall be uniformly applied to the milled material before the addition of any additive Hot Mix. The contractor shall determine the actual amount of recycling agent to be added, to address field conditions, and to optimize the properties of the in-place pavement.

The milled material, recycling agent (if required), and additive Hot Mix (if required) shall be uniformly mixed to produce a consistent, homogeneous final product.

Environmental Standards. The equipment shall be equipped with emission control devices in order to meet required, state and federal air quality standards.

12.324. Compaction and Leveling. The recycled mixture shall be compacted while the mix is still pliable immediately after it has been distributed and spread to a uniform depth. Compaction of the recycled bituminous pavement shall be done with vibratory steel-wheeled rollers, to a maximum level as determined by relative densities taken with a nuclear moisture/density gauge. The Engineer will take a density reading after each pass of the steel wheel roller until the readings no longer increase. The number of passes required to achieve this maximum density shall then be applied to the remainder of the recycled bituminous pavement. The Engineer may adjust the number of roller passes required if excessive damage to the pavement is occurring or if some other conditions change from those during which the number of passes were determined. A pass shall be considered to one of complete coverage of the area to be compacted.

12.325 Temperature Requirements. The recycled mixture shall have a temperature in a range between 185 oF and 300 oF as measured immediately behind the laydown machine.

12.326 Joints. The heating unit shall supply heat a minimum of 4 inches (100 mm) beyond the width of recycling.

12.327 Debris and Waste Material Disposal. The Contractor shall dispose of all debris and waste material in an environmentally safe manner and at locations approved by the Project Manager.

12.328 Weather Limitations. Hot in-place recycling of asphalt pavement shall not take place when the roadway surface is wet or when weather conditions otherwise prevent the proper handling or finishing of the bituminous mixture.

12.4 METHOD OF MEASUREMENT

12.41 Hot in-place recycling of asphalt pavement will be measured by the square yard.

12.42 When specified in the contract, additive Hot Mix will be measured by the ton.

12.43 When specified in the contract, recycling agent shall be measured by the gallon.

12.5 BASIS OF PAYMENT

12.51 The accepted quantities of hot in-place recycling of asphalt pavement will be paid for at the contract unit price per square yard (square meter) complete in place and will be considered full compensation for all materials, testing, labor, tools, equipment, and any appurtenances necessary to complete the work including cleaning of existing pavement, hauling and disposal of debris, heating, milling, mixing and relaying of recycled material, applying rejuvenating agents, and rolling and compacting of the recycled asphalt mixture

12.52 When specified in the contract, additive Hot Mix will be paid for by the ton.

Payment will be made under: