Section 310 — Cold In-Place Recycled Asphalt Base Course
Description
310.01This work consists of constructing cold in- place recycled asphalt base course with a self -propelled recycling train.
Material
310.02Conform to the following Subsections: Crushed aggregate 703.06 Engineered emulsion 702.02(d) Hydraulic cement 701.01 Lime for asphalt mixtures 725.03(c) Water for construction 725.01(c)
Construction Requirements
310.03Composition of Mix (Job -Mix Formula). Collect representative samples of the existing pavement to be milled. Replace removed pavement with asphalt concrete conforming to Section 403, Type II or approved cold patch material. Design a mix according to FLH T 524 and Table 310-1. Submit the JMF and the following for approval 30 days before production:
(a)Optimum emulsified asphalt binder content based on total mass of mixture;
(b)Source and grade of emulsified asphalt binder;
(c)Optimum moisture co ntent for dispersion and compaction based on total mass of mixture;
(d)Cement or lime content, if needed;
(e)Maximum density for the mixture;
(f)Bulk specific gravity for the mixture;
(g)Results of tests and applicable charts and graphs;
(h)A representative 300 -pound sam ple of pavement, if requested;
(i)Three, 1- gallon samples of emulsified asphalt binder, if requested; and
(j)A 15 -pound sample of cement or lime, if requested. Start production only after the mix design is approved. Submit a new mix design if there is a change i n a material source. Table 310-1 Cold In -Place Recycled 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(2) Average mass loss 5% maximum
(1)Follow the modified AASHTO T 283 procedures as indicated in FLH T 524.
(2)Use the listed testing conditions for the raveling test, unless otherwise directed.
310.04General. Establish existing pavement cross- section according to Subsection 152.05. Maintain the established cross-section or construct to proposed cross-section. Protect manholes, valve covers, a nd other buried facilities from damage. Clear, grub, and remove vegetation and debris within the area to be disturbed according to Section 201. Clean the pavement and edge of pavement of loose material, dirt, vegetation, an d other deleterious material.
310.05Equipment. Provide a self -propelled recycling train with the following major units:
(a)Pavement milling machine. Provide the following:
(1)Automatic depth controls to maintain the cutting depth to within ±¼ inch;
(2)Automatic system to maintain cross slope;
(3)Capable of milling the existing asphalt pavement material to the required depth in a single pass; and (4) 12.5 feet minimum cutter width.
(b)Crushing unit. Capable of screening and crushing material to the required size before mixing with emulsified asphalt.
(c)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 equipm ent that can apply emulsified asphalt and water to within ±0.2 percent of the required quantity by mass of milled material;
(4)Proportioning equipment with a digital meter for monitoring the flow rate and total milled material, emulsified asphalt, and water a pplied; and
(5)Capable of placing the mixture in a windrow without segregation.
(d)Paver. Provide a paver conforming to Subsection 401.05 that can pick up the entire windrow and feeding it into the paver hopper. Do not heat the s creed.
(e)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.
310.06Weather Limitations. Do not start work when fog, pr ecipitation, frost, or temperatures below 35 ºF are anticipated within 24 hours. Place cold in -place recycled asphalt base on a dry, unfrozen surface when the air temperature in the shade and the road surface temperature are 50 ºF and rising.
310.07Produc tion 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. Construct a control strip on the project at an approved location. Recycle a control strip that is one lane wide, 1500 f eet long, and the designated lift thickness. Use the construction procedures intended for the entire project. Stop production after construction of the control strip until the recycled base and the control strip are evaluated and accepted. Acquire three random samples of milled material from the control strip after the material has passed through the crushing unit, but before emulsified asphalt is added for Type A compaction. Verify that 100 percent passes the 1½ -inch sieve. Take density readings behind each roller pass to determine the roller pattern necessary to achieve the maximum in -place densit y (break point of compaction curve) according to ASTM D2950. Use the bulk specific gravity value from the mix design as a benchmark for evaluating the maximum in -place density achieved. Repeat the control strip process until an acceptable 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 measured as a part of the completed base course. Full production may start when a control strip is verified. Provide the CO with the maximum in -place density achieved (Type A compaction), and application rates of the emulsified asphalt, water, and other additives used on the accepted control strip. 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 of a new construction season.
310.08Pavement Recycling and Mixing. Mill the existing pavement to the required depth and width. Reduce oversize particles to a maximum size of 1½ inches. If cement or lime is required at the milling head or in the pugmill, incorporate cement or hydrated lime slurry to within ±10 percent of the approved application rate. Produce the cement or lime slurry using water in a slurry production unit equipped with scales and meters accurate to within 0.5 percent by mass. Agitate the transport and feed tanks to provide a consistent and pumpable lime slurry. Combine milled material with emulsified asphalt, water, and cement or lime 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. Do not disturb underlying material. Synchronize the recycling rate to allow for continuous operation of recycling train equipment. Continuously monitor and evaluate the milling, mixing, and placing operations to ensure optimum quality of the recycled asphalt base course. Adjust application rates in coordination with the CO based upon material variations.
310.09Spread ing, Compacting, and Finishing.
(a)Spreading. Spread and finish the recycled mix to the required 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 using the designated type:
(1)Type A compaction. Use roller patterns established durin g the control strip. Compact the recycled mix to obtain a minimum density of 97 percent of the control strip density. Measure in-place density according to ASTM D2950. If an area fails to meet required density, rework and recompact the area. If application rates of the emulsified asphalt from the approved mix design are changed by more than ±0.2 percent by mass of milled material, or if other material conditions distinctly change, reestablish roller pattern according to Subs ection 310.07.
(2)Type B compaction. Compact the recycled mix using the following equipment, sequence, and number of roller passes:
(a)Four to six roller passes with a double drum, vibratory roller having a mass of at least 5.5 tons and equipped with frequency and amplitude controls.
(b)Four to six roller passes with a pneumatic -tire roller having a mass of at least 2000 pounds per wheel and a contact pressure of at least 80 pounds per square inch.
(c)Two to four roller passes with a static steel -wheel roller with a pressure of at least 250 pounds per square inch. 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 pavement 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 inch measured at the end of the straightedge.
(d)Fog seal. Place a fog seal according to Section 406 on the surface of the recycled asphalt base. Use emulsified asphalt diluted to 50 percent by volume with water and apply it at a rate of 0.05 to 0.15 gallon per square yard. If necessary, place blotter according to Section 406.
310.10Construction Joints.
(a)Longitudinal joints. Make longitudinal joints coincide with each change in cross slope. Provide a minimum longitudinal overlap of 6 inches.
(b)Transverse joints. At the starting of each day’s recycling operations or after extended work stoppages, cut back into the completed work to ensure uniform material and depth across transverse joints.
310.11Curing and Maintenance. Keep traffic and construction equipment off the recycled asphalt base for 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. Maintain the recycled asphalt base to the correct 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 and recompact as necessary to restore the strength of the damaged material. Overlay the recycled asphalt base when the moisture content of the recycled asphalt base is less than 2.5 percent according to AASHTO T 255, but within 14 days after completing finishing operations regardless of moisture content.
310.12Acceptance. See Table 310-2 for sampling, testing, and acceptance requirements. Blotter material will be evaluated under Subsection 106.03. Cement and lime will be evaluated under Subsections 106.02 and 106.03. Emulsified asphalt binder will be evaluated under Subsections 106.03 and 106.04. Construction of the cold in- place 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.
Measurement
310.13Measure the Section 310 pay items listed in the bid schedule according to Subsection 109.02 .
Payment
310.14The accepted quantities will be paid at the contract price per unit of measurement for the Section 310 pay items listed in the bid schedule. Payment will be full compensation for the work prescribed in this Section. See Subsection 109.05 . Table 310-2 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
Source
Emulsified
asphalt (702.02 ) Measured & tested for conformance (106.04) Quality –
Subsection
702.021 per type & source of material Asphalt supplier Yes 30 days minimum before production –
Design
Emulsified
asphalt mix design Measured & tested for conformance (106.04) All – Subsection
310.03& FLH T 524 1 per submitted mix design Existing roadway Yes 30 days minimum before production For
Type A
compaction only Production Start -up (control strip)
Emulsified
asphalt mixture Measured & tested for conformance (106.04 ) Gradation – AASHTO T 27 3 minimum Before emulsion addition No Upon completing test –
Bulk specific
gravity (density) – FLH T 524 1 minimum Loose mix in windrow " " For
Type A
compaction only Density – ASTM D2950 &
Subsection
310.07Subsection
310.07In-place after compaction " " " Depth of cut – – 3 minimum Both ends of milling drum " " – Table 310- 2 (continued) 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
Emulsified
asphalt (702.02 ) Measured & tested for conformance (106.04 ) Bulk specific gravity (density) – FLH T 524 1 per change in material Loose mix in windrow No Upon completion of test For Type A compaction only Density – ASTM D2950 &
Subsection
310.071 per 2000 yd2
In-place
after compaction " End of shift " Depth of cut – – 1 per 500 ft
Both ends
of milling drum " " –
Process
control (153.03 ) Gradation – AASHTO T 27 1 per 3500 yd2 minimum
Before
emulsion addition No Upon completion of test –
Indirect
tensile strength(1) – FLH T 524 1 per 3500 yd2 " " 4 days "
Emulsified
asphalt (702.02 ) " Application rates – Calculation of yield rate,
Subsection
310.081 per tank load minimum – " " – Table 310-2 (continued) 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
Finished Product
Cold
recycled asphalt base Measured & tested for conformance (106.04 ) Surface tolerance – Straightedge measurement,
Subsection
310.09(c) Continuously, after compaction Finished recycled base surface No 24 hours –
(1)Transport samples immediately to a field material laboratory for indirect tensile strength compaction. Compact within 1 hour of sampling.