167 SECTION 404 COLD RECYCLED BITUMINOUS SURFACE AND PREMIXED BITUMINOUS PAVING MATERIAL DESCRIPTION
404.01.01 General. This work consists of preparing and placing recycled bituminous surface and furnishing,
stockpiling, loading, hauling, and placing premixed bituminous paving material. MATERIALS
404.02.01 Composition of Cold Recycled Mixtures. Compose the recycled bituminous mixture of reclaimed
asphalt pavement, a recycling agent, and lime slurry, as specified.
a.Gradation. Produce cold milled bituminous surface material, to be used in the recycling process, conforming to the following gradation requirements: Sieve Percent Passing by Mass 31.5 mm (1.25 in.) .......................................................................... 100 Separate cold milled bituminous material larger than 31.5 mm (1.25 in.) by screening or other means, break down by mechanical means to pass a 31.5 mm (1.25 in.) sieve and uniformly incorporate into the recycled mixture.
b.Recycled Material. The recycled asphalt mixture shall consist of milled material from the existing pavement, recycling agent, and lime slurry combined in the proportions specified herein, or as directed.
c.Recycling Agent. Add recycling agent to the cold milled material at an estimated rate of 1.5% by mass of the milled material. The actual application rate will be established in the field. Adjust the recycling agent application rate, with concurrence from the Engineer, as pavement conditions change. The request to adjust the application rate should be based on the opinion of a knowledgeable and experienced individual who works for the Contractor. The adjusted application rate shall be between 1.25% and 1.75% by mass of the milled material . If raveling or rutting of the cold recycled material occurs before the overlay is placed, take corrective measures and repair the cold recycled surface at own expense. The Department reserves the right to increase the application rate of recycling agent. In this case, the Department will accept any potential risk associated with the performance of the recycle mat caused by increasing the recycling agent. The type and grade of recycling agent will be specified in the contract. The recycling agent shall meet the applicable requirements of Section 703. For field test acceptance, refer to Subsection 408.02.02. Submit a 3.75 L (1 gal) sample of the recycling agent for approval at least 14 days before commencing recycle operations. In lieu of furnishing a sample of bituminous material, a passing test report may be submitted which has been previously issued by the Department’s Materials Division. The report shall be from the current calendar year. The material type and producer shall be the same as that to be utilized on the project. Add recycling agent to the cold milled material and mix to a homogeneous and uniformly coated mixture. Mix recycling agent in accordance with the temperature requirements of Subsection 406.03.04.
d.Additives. Introduce hydrated lime slurry into the cold milled material. Produce the hydrated lime slurry at the job site and introduce as specified below. Prepare lime slurry containing 1.5% calcium oxide (quicklime) by mass of the milled material conforming to the quicklime specification in ASTM C977. Use water in the slaking operation conforming to Section 722. Submit batch logs and solids content information for each batch.
404.02.02 Composition of Premixed Bituminous Paving Material. Compose the premixed bituminous
paving material of aggregates, bituminous material, and mineral filler. The type and grade of bituminous material and type of aggregate will be specified in the contract. 404 COLD RECYCLED BITUMINOUS SURFACE 168 Submit samples of the aggregate and cutback asphalt for the mix design according to Subsection 401.02.02. Aggregates shall meet the requirements of Section 705, for the grading size and type specified. Bituminous material shall meet the applicable requirements of Section 703. Mineral filler shall conform to Subsection 705.03.03. Mix the aggregate, bituminous material, and mineral filler in proportions conforming to the mix design and according to the ( a) Plantmixing Method of Subsection 404.03.06. CONSTRUCTION
404.03.01 Cold Recycle Equipment. Use equipment specifically designed for production of lime slurries.
Introduce the lime slurry at the mill head, as directed, by mass of the cold milled material. Calculate the mass of the cold milled material by kg/m3 (lb/ft3) for volume of cut. Use a metering device to accurately measure the amount of lime slurry required to within plus or minus 5%. Lime slurry rate of application shall be tied to the fo rward speed of the milling machine. Use agitators or similar equipment to keep the hydrated lime slurry in suspension when held in the lime slurry feed tank. Keep the hydrated lime slurry in suspension during transport using similar agitator equipment. The recycling train shall consist of a milling machine, crusher, and a pugmill mixer. Provide a milling machine which meets the requirements of Subsection 202.03.03 with the exception that the rotating powered mandrel drum shall be operated in the up -cut direction and studded with conical tungsten carbide tipped bits that produce a textured surface consisting of parallel ridges and furrows resembling a corrugated pattern. Horizontal spacing of the parallel ridges shall not be less than 15 mm (5/8 in.) or g reater than 22 mm (7/8 in.). The depth of the furrows shall not be less than 6 mm (1/4 in.) and not more than 13 mm (1/2 in.). Perform the cold milling operation in a manner that ensures the underlying material is not damaged. The primary milling machine shall have a minimum 3.6 m (12 ft) cutter capable of removing the existing pavement to the depths shown in the plans. A smaller milling machine may be used to mill the shoulders and miscellaneous areas. Provide a primary milling machine capable of discharg ing lime slurry on the cutting heads. The use of a heating device to soften the pavement will not be permitted. Use a portable crusher capable of reducing the oversize recycled materials to the specified size. Equip a portable continuous pugmill mixing plant with a belt scale and automatic controls to obtain the proper amount of recycling agent. Provide a pugmill which meets the requirements of Subsection 401.03.01. Equip the recycling train with positive displacement pumps and a computerized metering s ystem which can accurately meter the amount of recycling agent. Provide an interlocked computerized belt weighing system that measures the quantity of recycled material entering the mixing plant. Design the interlock so that recycling agent cannot be added until the recycled material enters the mixer. Equip overrides of the interlock system with short duration timers to prevent their continuous use. Use overrides only during start -up periods. Provide facilities to verify and calibrate the aggregate weigh system, recycling agent metering device, and lime slurry metering device. Calibrate the aggregate weigh system, recycling agent metering device, and lime slurry metering device before beginning recycling operations, no less than once a year, and any other time as directed. Calibration of the aggregate weigh system shall conform to Subsection 401.03.01 (4.c) with the exception that marinated material is not required. Calibration of the recycling agent metering device shall conform to Subsection 401.03.01 (4.d). Calibrate lime slurry metering device at two different speeds (lowest and highest speed of anticipated operation) in relation to the speed of the aggregate feed using the percentage of lime slurry set forth in the contract documents or as approved. Provide platform scales with a Certificate of Inspection as required in Subsection 109.01. COLD RECYCLED BITUMINOUS SURFACE 404 169 Furnish a vessel having a sufficient capacity to perform the calibration testing. A minimum of 3,785 L (1,000 gal) shall be the required am ount for a valid test. Calibrate the lime slurry feed so the masses shown on the metering device are within ± 5% of the weighed mass. Do not begin recycling operations until calibration procedures have been observed and approved. Do not operate outside th e parameters of the equipment calibration limits during recycling operations. Have readouts for the belt weighing device and computerized metering system that indicate the quantity in metric tons (tons) of recycled material and recycling agent being fed i nto the mixer at any given time. Provide totalizer readouts to allow determination of accumulative quantities of each constituent.
404.03.02 Pavers. Use a paver meeting the requirements of Subsection 401.03.03 and with a minimum power
of 127 kW (170 hp) t o place cold recycled mixtures to establish grade and cross slope.
404.03.03 Rollers. Provide a minimum of one pneumatic tired roller with an operating weight of at least
13.6 metric tons (15 tons) and not more than 18.1 metric tons (20 tons ). Provide a m inimum of one pneumatic tired roller with an operating weight of at least 22.7 metric tons (25 tons) and not more than 27.2 metric tons (3 0 tons ). Provide a minimum of two double drum vibratory steel wheeled rollers weighing at least 9.1 metric tons (10 to ns). Use rollers in good condition with an operational, working water system. Use a combination of steel wheeled, under static or vibratory mode, and pneumatic tired rollers to establish a rolling pattern with the appropriate combination of rollers and nu mber of passes that will provide maximum compaction without cracking the recycle mat. Do not compact outside the edge of the existing pavement width limits to prevent roadway spread.
404.03.04 Weather Limitations. Do not begin in -place recycling until pav ement surface temperature is 16 °C
(60 °F) and rising and the atmospheric temperature in the shade is 10 °C (50 °F) and rising. Do not begin in -place recycling if it is anticipated the atmospheric temperature will drop below 2 °C (35 °F) within 48 hours of mixing, or during stormy weather. Consider weather stormy when the rate of precipitation exceeds the rate of evaporation. Stop recycling operations a minimum of 3 hours before sunset to allow completion of initial compaction while surface temperature is 16 °C (60 °F) or above. If it rains on the recycled surface during the overlay operation, suspend the paving operation. The Engineer will take 3 randomly selected samples from the recycled surface to be overlaid a minimum of 2 hours after it rains. If the average moisture content of the samples is 2.0% or less as determined by Test Method No. Nev. T112, proceed with paving. If the average moisture content is greater than 2.0%, delay paving for a minimum of 72 hours or until the average moisture content fro m 3 more samples is 2.0% or less.
404.03.05 Repair of Failed Pavement Subgrade Areas. Repair failed pavement subgrade areas encountered
during the recycling operations as directed. Perform repairs before the limits of the failed areas increase in size. Work will be immediately suspended if the limits of the failed areas increase. When suspension occurs, repair the failed areas before any other operation proceeds. Working days will continue to be assessed during the suspension period. The repaired areas wil l be paid for according to Subsection 109.03. If the designated areas are not repaired before the areas increase in size, make repairs to the expanded failed pavement subgrade areas at no cost to the Department. Repair the failed pavement subgrade areas b y excavating to a depth of 450 mm (18 in.) and place a structural section of 300 mm (12 in.) of Type 1 Class B Aggregate Base and 150 mm (6 in.) of dense -graded plantmix bituminous surface. If dense graded plantmix is not available, place premixed bitumino us surfacing as a temporary patch until dense graded plantmix becomes available. Remove and replace the premixed bituminous surfac ing with dense graded plantmix.
404.03.06 Mixing. (a) Plantmixing Method. Mix the aggregate with the cutback asphalt at a cen tral mixing plant
according to Subsection 401.03.01. If the moisture content of the aggregate is 2% or less by mass of the dry aggregate, as determined by Test Method No. Nev. T112, mixing of the materials without passing the aggregate through a dryer will be permitted. Add mineral filler according to Subsection 401.03.08, Marination Method.
b.Recycling Train. Combine the milled material, recycling agent, and lime slurry in the specified quantities or as directed. Continue mixing until the recycling age nt and lime slurry have been distributed uniformly. 404 COLD RECYCLED BITUMINOUS SURFACE 170 404.03.07 Spreading, Compacting, and Finishing. Except for unavoidable delay or breakdown, recycle and place recycled pavement, with a paving machine meeting the requirements of Subsection 404.03.02, at a rate sufficient to provide continuous operation of the paving machine. If paving operations result in excessive stopping of the paving machine, suspend recycling and paving operations until the synchronization of the rate of recycle with the capacity of t he paving machine can be attained. Place the recycled mixture on the roadbed in front of the paver in a consistent windrow. Remove, by hand, and dispose of all visible oversized crack filler in the cold recycled material windrow. Use windrow equipment c apable of removing and loading all of the recycled mixture into the spreading and finishing machine. Lay the recycled mixture on the surface, spread and strike off to established grade and elevation. After the cold recycled mixture has been spread and su rface irregularities have been corrected, delay breakdown rolling for 1 to 2 hours. Thoroughly and uniformly compact the recycled mixture to the required density without undue displacement or cracking. Prevent excessive edge sloughing by compacting the lon gitudinal joint first followed by initial passes that shall begin on the low side and progress to the high side by overlapping longitudinal passes parallel to the pavement centerline. The recycled surface will be visually inspected for approval. Apply an emulsified asphalt (diluted) fog seal to the recycled mixture. Following the fog seal, apply a sand blotter. The fog seal shall be a mixture of 50% recycling agent and 50% added water by mass . Mix the recycling agent and added water according to Subsection 405.02.01 . Do not turn hauling equipment in areas where such turning may result in tearing, gouging, or distortion of the previously laid pad of recycled material. Immediately repair any damage at no cost to the Department. After initial compaction, and before recompaction, open the recycled mixture to public traffic and allow the mixture to cure a minimum of 10 days before overlaying. Perform recompaction between 3 and 15 days after initial compaction or as directed. Do not perform rolling when the surface temperature is below 32 °C (90 °F). Recompact the entire recycled pavement area with at least one steel wheeled roller weighing at least 9.1 metric tons (10 tons), in the static mode, and one pneumatic roller weighi ng at least 22.7 metric tons (25 tons). Compaction of the recycled pavement will be evaluated in accordance with Subsection 402.03.06, (c) Control Strip (Method C). If procedures are no longer achieving acceptable results, a change in the compaction equi pment and/or methods will be required. Correct any displacement of the mat, regardless of thickness, occurring as a result of the reversing of the direction of a roller, or from other causes. Moisten steel roller wheels with water to the least extent nece ssary to prevent pickup. When the rolling causes undue tearing, displacement, cracking or shoving, make changes in compaction equipment and/or rolling procedures to alleviate the problem. Construct joints in accordance with the requirements of Subsection 401.03.12. Keep the longitudinal joints free of loose material. Overlap the cold milled longitudinal joints a minimum of 100 mm (4 in.) when making adjacent recycling passes.
404.03.08 Surface Tolerances. The top surface of the completed recycled pavemen t will be tested with a
3.6 m (12 ft) straightedge parallel to, and perpendicular to, the centerline and shall not vary by more than 6 mm (1/4 in.) from the lower edge of the straightedge.
404.03.09 Conditions of Acceptance and Corrective Actions for Cold Recycle Mixture. Acceptance for
payment of the cold recycle will be by visual inspection of the mixture on the roadway following initial rolling and recompaction requirements. Correct any mixture not uniformly mixed or that ravels as follows:
a.Reproce ss or replace any area showing an excess or a deficiency of emulsified asphalt. COLD RECYCLED BITUMINOUS SURFACE 404 171 (b) If raveling occurs, immediately provide traffic control and additional rolling. Repair the recycled surface before proceeding with any other work. Reprocess or repair by approved methods, at own expense. Repair any damage before overlaying. When tests show the recycled surface is not within the specified tolerance, take immediate action to correct equipment or procedures in the paving operation to eliminate the unacceptable pavement roughness. Remove all cold patches larger than 2 m2 (20 ft2) and replace with hot mix prior to dense -graded overlay.
404.03.10 Premixed Bituminous Paving Material. Clear the stockpile area of all brush, rubbish and
deleterious matte r. The premixed bituminous paving material is to be stockpiled at an exact location and in a manner as directed before the start of any cold recycling, roadbed modification, crack and seating or any other operation that may require the use of the premixed bituminous paving material to repair the surface. Place the premixed bituminous paving material, when directed, for making necessary repairs to the roadway surface. METHOD OF MEASUREMENT
404.04.01 Measurement. Recycled Bituminous Surface (depth) will b e measured by the square meter
(square yard). No measurement will be made for overlap at longitudinal joints. Lime (Cold Recycle) will be measured by the metric ton (dry ton). Bituminous material will be measured by the metric ton (ton). Emulsified asph alt (diluted) will be measured by the metric ton (ton) of diluted mixture. Sand blotter will be measured and paid for according to Section 407. Premixed bituminous paving material will be measured by the metric ton (ton) or cubic meter (cubic yard) of completed mixture of aggregate, mineral filler, and bituminous material in stockpile. Haul and place premixed bituminous paving material will be measured by the metric ton (ton), square meter (square yard) or cubic meter (cubic yard), of the completed mixtu re acceptably placed and compacted on the roadbed. When haul and place premixed bituminous paving material is to be measured by the force account basis, measurement will be made according to Subsection 109.03. BASIS OF PAYMENT
404.05.01 Payment. The accepted quantities, measured as provided above, will be paid for at the contract
price per unit of measurement for the pay items listed below that are shown in the proposal. Payment will be full compensation for the work prescribed in this Section. Payme nt will be made under: Pay Item Pay Unit Recycled Bituminous Surface (depth) ................................ ................................ ................................ .......... Square Meter (Square Yard) Lime (Cold Recycle) ................................ ................................ ................................ ................................ ........................ Metric Ton (Ton) Emulsified Asphalt (type) ................................ ................................ ................................ ................................ ................. Metric Ton (Ton) Cutback Asphalt (grade) ................................ ................................ ................................ ................................ .................. Metric Ton (Ton) Premixed Bituminous Paving Material ................................ ................................ ................... Metric Ton (Ton), Cubic Meter (Cubic Yard) Haul and Place Premixed Bituminous Paving Material ................................ ..................... Metric Ton (Ton), Square Meter (Square Yard), Cubic Meter (Cubic Yard), Force Account 173 SECTION 405 TACK COAT DESCRIPTION
405.01.01 General. This work consists of applying a bituminous material tack coat.
MATERIALS
405.02.01 Bituminous Material. The bituminous material shall conform to the applicable requirements of
Section 703. Emulsified asphalt for the tack coat shall be Emulsified Asphalt, Type SS -1h (Diluted); however, Emulsified Asphalt, Type SS -1 (Diluted), Emulsified Asphalt, Type CSS -1 (Diluted), Emulsified Asphalt, Type CSS -1h (Diluted) or Emulsified Asphalt, Type CQS -1nv (Diluted) may be substituted. Emulsified asphalt (diluted) shall be a mixture of 70% emulsified asphalt and 30% added water by mass. To accomplish this mixing, fill th e distributor partly with water, and then add the emulsified asphalt. Spray the remaining required water into the tank under pressure and then thoroughly circulate within the distributor. CONSTRUCTION
405.03.01 Equipment. Equipment for heating and applying the emulsified asphalt shall meet the following
requirements:
a.Capable of heating asphalt evenly.
b.Power unit for the pump, and full circulation spray bar adjustable to 4.3 m (14 ft) wide.
c.Positive controls including tachometer, press ure gages, volume measuring device, and calibrated tank, to uniformly apply asphalt within 0.10 L/m2 (0.02 gal/yd2) of the required rate.
d.Thermometer for measuring temperatures in the tank.
e.Use the correct size nozzles and application pressure fo r the type and grade of asphalt and speed of distributor. Nozzles shall be free from damage, unclogged, and freely spraying. Nozzles shall be uniformly angled from spray bar such that the spray fans do not interfere with other spray fans. Special end -nozzl es or shields installed on the end of the spray bar shall be adjusted to provide clean, uniform application and edges without streaks. Adjust and maintain the spray bar height to provide uniform double or triple lap coverage of bituminous material spread w hile preventing wind or other distortion.
405.03.02 Weather Limitations. Do not apply emulsified asphalt when the surface to be treated is damp, wet,
when weather conditions are unsuitable, or when the atmospheric or surface temperature is below 4 °C (40 °F).
405.03.03 Preparation of Surface. Patch and clean the surface and remove any irregularities from the surface.
Clean the edges of existing pavements which are to be adjacent to new pavement. See Subsection 105.1 5.
405.03.04 Application of Bituminous Materials. Apply emulsified asphalt tack coat on surfaces to receive
paving and between all paving courses unless otherwise directed. The temperature of the emulsified asphalt shall conform to Subsection 406.03.04. Uniformly apply the emulsified asphalt to the surface, including any adjacent vertical edges. Apply the emulsified asphalt in such manner as to offer the least inconvenience to traffic and to permit one -way traffic without pickup or tracking of the bituminous material. Place the covering course over tack that is clean, free of tracking and adequately set. Do not apply more tack than can be covered in the same shift.
Source: Nevada Standard Specifications for Road and Bridge Construction, 2014 Edition. Pages 173–178 of 610.