Section 309 — Cold Central Plant Recycled Asphalt Base Course

COURSE

Description

309.01This work consists of constructing one or more courses of cold central plant recycled asphalt base using milled asphalt material.

Material

309.02Conform to the following Subsections: Engineered emulsion 702.02(d) Hydraulic cement 701.01 Lime for asphalt mixtures 725.03(c) Water for construction 725.01(c)

Construction Requirements

309.03Composition of Mix (Job- Mix Formula). Collect representative samples of the recycled asphalt pavement to be used. Reduce oversize particles to no more than 1½ inches. Replace removed pavement with asphalt concrete conforming to Section 403, Type II. Design a mix according to Table 309-1. Submit the JMF and the following for approval 30 days before production:

(a)Optimum engineered emulsion content based on total mass of mixture;

(b)Source of engineered emulsion;

(c)Optimum moisture content for dispersion and compaction based on total mass of mixture;

(d)Lime or cement content, if required;

(e)Results of tests and applicable charts and graphs;

(f)A representative 300 -pound sample of pavement, if requested;

(g)Three 1 -gallon samples of engineered emulsion, i f requested; and

(h)A 2-pound sample of lime or cement, if requested. Start production only after the mix design is approved. Submit a new mix design if there is a change in a material source. Table 309-1 Cold Central Plant Asphalt Base Course Mix Design Parameters

Property Requirement

Indirect tensile strength, AASHTO T 283(1) Tensile strength dry 70 psi minimum Tensile strength ratio 70% minimum Raveling test, ASTM D7196, 4 -hour cure at 50 °F, 50% humidity Average mass loss 5% maximum

(1)Follow Section 7 for laboratory- mixed, laboratory -compacted specimens. Compact the mixture to the design air voids. Instead of Subsection 7.5, cure samples for at least 16 hours and no more than 48 hours at 140°F until constant weight is attained . Inst ead of the Subsection 10.4 saturation range, use a target range from 55 to 75 percent saturation. Do not use the conditioning cycles in Sections 10.4.9 and 10.4.10. Instead, condition the sample in a water bath at 77°F for 24 hours.

309.04Equipment.

(a)Pugmill and proportioning equipment. Provide the following:

(1)Capable of continuously mixing the milled material with emulsified asphalt, water, lime, and other additives to produce a uniform and homogenous mixture;

(2)Belt scale for continuous weighing of milled and sized material with an interlocked computer controlled liquid metering device that can automatically adjust the flow of asphalt emulsion to the mass of milled material coming into the mixer;

(3)Proportioning equipment that can apply emulsified asphalt and w ater to within ±0.2 percent of the required quantity by mass of milled material; and

(4)Proportioning equipment with a digital meter for monitoring the flow rate and total milled material, emulsified asphalt, and water applied.

(b)Paver. Provide a paver conformi ng to Subsection 401.05 that can pick up the entire windrow and feeding it into the paver hopper. Do not heat the screed.

(c)Rollers. Provide double -drum steel -wheel and pneumatic -tire rollers in sufficient quantity and size to obtain the required density. Provide pneumatic- tire rollers weighing at least 30 tons.

309.05Weather Limitations. Do not start work when fog, precipitation, frost, or temperatures below 35 ºF are anticipated within 24 hours. Place cold central plant recycled asphalt base on a dry, unfrozen surface when the air temperature in the shade is 50 ºF and rising and the pavement surface temperature is 40 ºF and rising.

309.06Production Start- Up Procedures.

(a)Preparatory phase meeting. Conduct a pre -recycling preparatory phase meeting according to Subsection 153.06(a) at least 7 days before the start of recycling operations .

(b)Control strip. Provide 7 days’ notice before starting production of a cold central pla nt recycled asphalt base. On the first day of production, produce sufficient cold central plant recycled asphalt base to construct a 1500-foot- long control strip, one -lane wide, and at the designated lift thickness. Construct the control strip on the proje ct at an approved location. Construct the control strip using the production, lay- down, and compaction procedures intended for the entire mix. Document roller pattern and if roller was operated in vibratory or static mode. Provide frequency and amplitude settings if operated in vibratory mode. Provide this documentation to the CO after completion of the control strip. Stop production after construction of the control strip until the cold central plant recycled asphalt base and the control strip are accepted . Repeat the control strip process until an accepted control strip is produced. See Subsection 106.01 for the disposition of material in rejected control strips. Accepted control strips may remain in place and will be accepted and measured as a part of the completed pavement. When a control strip is accepted, full production may start. Use these start -up procedures when changing construction procedures, resuming production after a termination of production due to unsatisfactory quality according to Subsection 106.04, or starting a new construction season.

309.07Mixing. Obtain milled material under Section 413. Reduce oversize particles to no more than 1½ inches. Combine milled material with emulsified asphalt, water, and lime or cement at the approved application rates to produce a homogenous and uniformly coated mixture. Maintain the emulsified asphalt temperature within the range recommended by the supplier. Adjust application rates in coordination with the CO based upon material variations. 309.08 Spreading, Compacting, and Finishing. Transport material according to Subsection 401.11.

(a)Spreading. Spread and finish the recycled asphalt base to the required line, grade, and cross - section.

(b)Compacting. Start compaction within 60 minutes of spreading. Use pneumatic -tire rollers until no displacement is observed. Use steel -wheel rollers, in static or low -amplitude vibratory mode, to achieve final density and eliminate pneumatic -tire roller marks. Do not park or idle rollers on uncompacted material. Compact the recycled mix using the following equipment, sequence, and number of roller passes:

(1)Six to twelve roller passes with a self -propelled pneumatic -tired roller having smooth pneumatic tires staggered in position to provide overlap between the front and rear tires, with a weight of at least 2000 pounds per wheel and a contact pressure of 80 pounds per square inch;

(2)Four to ei ght roller passes with a double -drum, vibratory roller having a minimum mass of 5.5 tons and equipped with frequency and amplitude controls; and (3) Four to six roller passes with a static steel- wheel roller with a pressure of at least 250 pounds per square in ch. Compact the material with approved tampers or compactors along curbs, headers, walls, and places not accessible to the roller.

(c)Finishing. Produce a surface that is smooth, dense, and free of ruts, ridges, and loose material. Measure the surface using a 10- foot metal straightedge at right angles and parallel to the centerline. Defective areas are deviations between the surface and the bottom of the straightedge more than ⅜ inch measured between two contacts of the straightedge or deviations more than ⅜ i nch measured at the end of the straightedge.

309.09Construction Joints.

(a)Longitudinal joints. Make longitudinal joints coincide with each change in cross slope. Provide a longitudinal overlap of at least 4 inches.

(b)Transverse joints. At the start of each da y’s recycling operations or after a 2- hour work stoppage, cut back into the completed work to ensure uniform material and depth across transverse joints.

309.10Curing and Maintenance. Keep traffic and construction equipment off the recycled asphalt base for initial curing at least 2 hours after completing compaction and until it is sufficiently stable to withstand raveling, marring, and permanent deformation. Route hauling and other construction equipment uniformly over the full width of the recycled asphalt base to minimize non -uniform compaction. After initial curing, place a fog seal according to Section 406 on the surface of the recycled asphalt base at a rate of 0.05 to 0.10 gallon per square yard. Maintain the recycled asphalt base to the correct line, grade, and cross -section. Provide additional rolling with a steel- wheel roller to recompact and maintain a dense surface. Use a power broom to remove loose particles. If the recycled asphalt base ravels or loses stability, density, or finish, reprocess, recompact and finish according to Subsection 309.08 as necessary to restore the strength of the damaged material. Overlay the recycled asphalt base when the moisture content is less than 2.5 percent according to AASHTO T 255, but within 14 days after completing finishing operations regardless of moisture c ontent.

309.11Acceptance. See Table 309-2 for sampling, testing, and acceptance requirements. Cement and lime will be evaluated under Subsections 106.02 and 106.03. Engineered emulsion will be evaluated under Subsections 106.02 and 106.03. Milled material will be evaluated under Subsections 106.02 and 106.04. Construction of the cold central plant recycled asphalt base course will be evaluated under Subsections 106.02 and 106.04. Fog seal will be evaluated under Section 406.

Measurement

309.12Measure the Section 309 pay items listed in the bid schedule according to Subsection 109.02 .

Payment

309.13The accepted quantities will be paid at the contract price per unit of measurement for the Section 309 pay items listed in the bid schedule. Payment will be full compensation for the work prescribed in this Section. See Subsection 109.05 . Table 309-2 Sampling, Testing, and Acceptance Requirements

Material or

Product

(Subsection) Type of

Acceptance

(Subsection) Characteristic Category Test Methods

Specifications Sampling

Frequency Point of

Sampling Split

Sample Reporting

Time Remarks

Production

Engineered

emulsion (702.02(d) ) Process control (153.03) Application rates – Calculation of yield rate 1 per tank load minimum – " " –

Finished Product

Cold

recycled asphalt base Measured & tested for conformance (106.04) Surface tolerance – Straightedge measurement,

Subsection

309.08(c) Continuously, after compaction Finished recycled base surface No 24 hours –