Section_416.pdf

Section 416

Section 416. — CONTINUOUS COLD RECYCLED

ASPHALT BASE COURSE

Description

416.01 This work consists of constructing a recycled asphalt base course using methods and equipment capable of recycling and relaying the material in a one-pass operation.

Continuous cold recycled asphalt base course compaction is designated type A or B as shown in Subsection 416.08.

Emulsified asphalt grades for emulsified binder agent and sealing emulsion are designated as shown in AASHTO M 140 or M 208.

Material

416.02 Conform to the following Subsections:

Emulsified binder agent 702.03 Quicklime 702.08(c) Recycling agent 702.06 Sealing emulsion 702.03 Water 725.01(c)

Construction Requirements

416.03 Submittals.

(a) Material. When type A compaction is designated, submit the following at least 28 days before recycling:

(1) Ten pavement cores at least 6 inches in diameter from randomly selected sites;

(2) Source of and 2 gallons of emulsified binder agent;

(3) Two pounds of quicklime if quicklime is included in the bid schedule; and

(4) Material safety data sheets.

The CO will perform a mix design and provide an initial application rate for emulsified binder agent, recycling agent, and quicklime, as applicable.

(b) Specialty qualifications. At least 14 days before recycling, submit the name, qualifications, and references of a competent person with extensive recycling experience to be responsible for the recycling operations. This individual's responsibilities are identified in Subsection 416.07(c).

(c) Sequence of operations. At least 14 days before recycling, submit the proposed equipment, manpower, and sequence of operations.

416.04 Surface Preparation. Clean the existing surface of all loose material, dirt, or other deleterious substances by approved methods. Clear, grub, and remove all vegetation and debris within 2 feet of the pavement to be recycled.

416.05 Weather Limitations. Place the emulsified asphalt pavement on a dry, unfrozen surface only when the air temperature in the shade is above 50 ºF and the pavement surface temperature is above 40 ºF.

Do not place emulsified asphalt mix when fog, showers, rain, frost, or temperatures below 35 ºF are anticipated within 24 hours following the placement of the mix.

416.06 Pavement Milling. Use equipment that is:

(a) Self-propelled;

(b) Equipped with automatic depth controls;

(c) Capable of maintaining the required cutting depth;

(d) Capable of milling to the required depth in a single pass of half the existing pavement width or one lane width, whichever is greater; and

(e) Capable of screening and crushing material.

Do not disturb underlying material.

Reduce oversize particles to a maximum particle size of 1 inch.

416.07 Mixing and Proportioning. Produce a homogeneous and uniformly-coated mixture of milled paving material, emulsified binder agent, and water.

(a) Equipment. Use self-propelled equipment with:

(1) A positive displacement pump with an automatic interlock system that allows the addition of emulsified binder agent and recycling agent only when milled material is present in the mixing chamber and automatically shuts off when the machine is stopped. The pump must be capable of supplying from 0 to 10 percent emulsified binder agent by mass of aggregate to within ±0.1 percent of the desired application rate.

(2) A weighing device calibrated and synchronized with the emulsified binder agent metering pump to regulate the emulsified binder agent added to the material in the mixing chamber.

(3) A meter for monitoring flow rate and total delivery of emulsified binder agent and recycling agent into the mix.

(b) Quicklime. When there is an item in the bid schedule for quicklime, incorporate quicklime using one of the following methods:

(1) Dry. Use a calibrated spreader to place pelletized quicklime on the existing pavement ahead of the recycling operation. Place quicklime within the width of the milling head. After milling, add sufficient water to slake the quicklime.

(2) Slurry. Use mixing equipment designed for producing lime slurries. Equip the slurry plant operations with scales and meters to proportion quicklime and water within 0.5 percent by mass. Agitate the transport tanks to keep the lime in suspension. Provide a consistent pumpable lime slurry with the appropriate amount of quicklime to be incorporated into the recycled asphalt pavement.

Introduce the lime slurry at the milling head. Meter lime slurry to within ±10 percent of the required amount.

(c) Monitoring. Continuously monitor and evaluate the milling/mixing/placing operations and make adjustments to proportioning or operational procedures as appropriate to maximize the quality and serviceability of the final recycled asphalt base product. Adjustments may include the application rate for emulsified binder agent, application of quicklime, application of water, changes to the recycling operation to address distinct variations in existing pavement and material conditions, changes due to variation in shoulder material, and termination of operations due to abnormal or questionable product.

416.08 Spreading, Finishing, and Compacting. Use a paver conforming to Subsection

401.05 that is capable of picking up the entire windrow and feeding it into the paver hopper.

Do not heat the screed.

Place, spread, and strike off the recycled mix to the required line, grade, and elevation.

(a) Initial compaction. Compact using the designated type:

(1) Type A. One to 2 hours after placing the recycled mix, compact the recycled mix according to Subsection 401.14 except use pneumatic roller(s) weighing at least 27 tons. Do not park or idle rollers on uncompacted recycled material.

Initially compact with pneumatic rollers until no displacement is visible. Use steel-wheel roller(s), either in static or vibratory mode, to achieve final density.

Compact the recycled mix until it obtains a minimum density, immediately after placing and rolling, of 88 percent of a laboratory specimen prepared according to AASHTO T 247 at 140 ºF. Measure the density of the laboratory specimen according to AASHTO T 166. Measure the density of the inplace recycled mix according to AASHTO T 310.

(2) Type B. Compact the recycled mix using the following equipment, sequence, and number of roller passes:

(a) 6 to 8 roller passes with a double drum, vibratory roller having a minimum mass of 5.5 tons and equipped with frequency and amplitude controls.

(b) 8 to 12 roller passes with a pneumatic-tired roller having a minimum mass of 2000 pounds per wheel and a contact pressure of 80 pounds per square inch.

(c) 4 to 6 roller passes with a static steel-wheel roller with a minimum pressure of 250 pounds per square inch.

Keep all traffic and equipment off of the recycled asphalt base for at least 2 hours after completing initial compaction.

(b) Pavement smoothness. Immediately after initial compaction is complete, measure pavement smoothness according to Subsection 401.16(c). Defective areas are surface deviations in excess of 3/8 inch in 10 feet. Correct defective areas according to Subsection 401.16(d).

(c) Final compaction. Compact using the designated type:

(1) Type A. Before the next surfacing course is placed, compact the recycled mix until it obtains a minimum density of 92 percent of the laboratory specimen.

(2) Type B. At least 3 days after initial compaction, continue compactive effort with the pneumatic and static steel wheel rollers when the surface temperature is greater than 72 ºF. Use a minimum of four passes over the entire surface with each roller.

(d) Curing. Repair damage to the recycled asphalt base.

(1) Recycled mix with quicklime. Overlay the recycled base within 21 days after recycling.

(2) Recycled mix without quicklime. Overlay after the recycled base has cured 7 to 21 days. Do not overlay until the moisture content of the recycled base is less than or equal to 1.5 percent according to AASHTO T 310 or until 21 days after recycling.

416.09 Fog Seal. When there is a pay item for fog seal in the bid schedule and when directed by the CO, place a fog seal on the surface of the recycled base after final compaction. Dilute the fog seal 50 percent by volume with water and apply it at a rate of

0.04 to 0.20 gallons per square yard. Place blotter according to Section 411.

416.10 Acceptance. See Table 416-1 for sampling and testing requirements.

Emulsified binder material will be evaluated under Subsections 106.03, 106.04, and 702.09.

Quicklime will be evaluated under Subsection 106.03.

Construction of continuous cold recycled asphalt base course will be evaluated under Subsections 106.02 and 106.04. Type A compaction will be evaluated under Subsection 106.04.

Pavement smoothness will be evaluated under Subsections 106.02 and 106.04.

Blotter material will be evaluated under Section 411.

Measurement

416.11 Measure the Section 416 items listed in the bid schedule according to Subsection

109.02 and the following as applicable.

Measure the square yard width horizontally to include the top of base width including designed widening. Measure the square yard length horizontally along the centerline of the roadway.

Measure sealing emulsion including water used for dilution.

Payment

416.12 The accepted quantities will be paid at the contract price per unit of measurement for the Section 416 pay items listed in the bid schedule. Payment will be full compensation for the work prescribed in this Section. See Subsection 109.05.

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