for Highway Construction Page 290 of 71 5 SECTION 430 – COLD IN -PLACE RECYCLED (CIR) PAVEMENT
430.01 Description.
Cold mill the existing bituminous pavement to the width and depth as specified, mix emulsified asphalt recycling agent (EARA), recycling additive (dry portland cement or hydrated lime slurry) and water with the millings, re -lay and compact the mixture in place. Produce a hydrated lime slurry onsite. Direct application of dry quicklime to the roadway is not allowed.
430.02 Materials.
The Department defines EARA as an emulsion used for CIR designed to allow acceptance of rolling traffic at 75°F and 50 percent humidity within an optimal time of 2 hours.
1.Emulsion. Ensure EARA meets the property requirements specified in 702. Ensure additives added to the emulsion mix to provide the quick set properties are approved by the man ufacturer.
2.For cold- milled bituminous material, meet the following gradation requirement: Sieve Size Percent Passing 1¼ inch 100
3.Lime. Use granular quicklime (CaO) or hydrated/slaked lime (Ca(OH)2) to produce the lime slurry. Provide quicklime as specified in 720.06.A. The Engineer will require certification that the chemical composition and physical property have been met.
4.Cement. Use Type II portland cement as specified in 701.
5.Water. Provide water without harmful soluble salts and a quality that the asphalt will not separate from the emulsion before the CIR pavement is in place.
6.Materials Acceptance. Asphalt emulsion and aggregate is accepted based on the following:
a.EARA. A manufacturer’s certification is required, including the viscosity and residue percent obtained at the plant. Sample the EARA twice a day from a random truck or trailer onsite in accordance with AASHTO T 40 and ship to the Central Materials Laboratory within 3 calendar days for viscosity and evaporation residue verification testing. When the EARA does not meet s pecifications, a price adjustment will be made as specified in the Department Laboratory Operations Manual Section
350.02 03.
Perform field testing for the purpose of ensuring the asphalt emulsion has not broken excessively during transportation to the project site. Before introduction to the pug mill mixer , check each load of emulsion for “shod” by sieving as described in AASHTO T 59 (sodium oleate solution is not required). Submit the results.
b.Cold milling. Before starting compaction , submit the gradation test at the minimum required frequency of 1 test per lane mile. for Highway Construction Page 291 of 715 c. CIR Pavement . Perform density testing for control strips and test sections in accordance with AASHTO T 355 or AASHTO T 343.
430.03 Construction Requirements.
A.General. Place the initial lift of HMA within 48 hours after curing and supplemental compaction is complete, unless reprocessing is required. The temperature limitations for plant mix paving will apply. Plan to remove and replace the recycled material in a continuous process, one lane of the roadway at a time, which will allow the material t o be compacted and finished in the same day. Before opening to traffic, roll loose material on the newly recycled surface into the mat. Apply a fog coat full width at a rate of 0.12 gallon per square yard. After the fog coat, apply blotter as specified in 703.07 to the fog- coated a rea. Obtain the Engineer’s approval before the recycled roadway is opened to traffic. Control dust at all times. Minimize aggregate fracture during recycling. Recycle the existing pavement with a recycling train. Use hydrated lime slurry or dry spread portland cement . Lime for Recycled Treated Pavement . Meet the following:
1.Lime Slurry Plant. Use mixi ng equipment specifically designed for production of hydrated lime slurries. Equip plants with scales and meters to accurately proportion lime and water within 0.5 percent by weight. Provide transports to convey the slurry to the roadway with sufficient agitation to prevent settlement and maintain a uniform homogeneous mixture.
2.Lime Metering. Introduce the hydrated lime slurry by a spray bar located at the mill head as required by the Engineer by weight of CIR material. Calculate the weight of the CIR material by pounds per cubic yard for volume of cut. Use metering device to accurately measure the quantity of hydrated lime slurry required to within 10 percent.
3.Lime Feed Tank. Use agitators or similar equipment to keep hydrated lime slurry in suspension and maintain a uniform homogeneous mixture when held in the lime slurry feed t ransport tank. Provide hydrated lime slurry in a uniform pumpable consistency and uniformly incorporate into the CIR material at the specified percentage. Ensure the rate of application is approximately 1½ percent of dry quicklime added by weight to the existing bituminous pavement to be recycled. Spread dry cement in front of the recycle train no more than 100 feet in front of the cold planer so it is incorporated into the CIR material at the specified percentage.
B.Equipment.
1.Recycling Train. Provide a recycling train with t he following major components: planing machine crusher, pug mill mixer , and EARA storage .
a.Planing Machine. Provide a self -propelled planing machine having at least a 12- foot-wide rotary cutter capable of evenly removing t he existing pavement to a depth of 4 inches in a single pass. for Highway Construction Page 292 of 715 Ensure the unit is capable of accurately establishing profile grades within a tolerance of 0.25 inch by reference from the existing pavement or from independent grade control, and have a positive means for controlling cross slope elevations and an effective means for removing material from the surface. The Engi neer will not allow a heating device to soften the pavement. Equip the unit to discharge water into the mixing chamber or at the milling head, with a fully variable control and meter capable of accurately measuring the rate of feed.
b.Crush er. Provide a portable type crusher capable of reducing the oversized recycled materials to the specified size. The Engineer may require additional screening and crushing.
c.Pug Mill Mixer . Mix the cold recycled bituminous mixture in a pug mill type plant capable of providing a mix of RAP , recycling additive EARA, and water. Equip the pug mill with positive control for linking the RAP , EARA, and water feeds in a manner that will maintain a constant ratio of each part. Equip the plant with facilities that the Contractor can verify and calibrate the RAP, EARA, and water quantities by an acceptable method. Measure the RAP by weight and proportion the EARA and water by weight or by volu me. Ensure the equipment is capable of feeding and maintaining a constant rate of RAP within a tolerance of plus or minus 5 percent (by total weight) of the designated amount and a constant rate of EARA and water feeds within plus or minus 0.2 percent (by total weight) of the designated quantities . Equip the mixing plant with positive displacement pumps and a computerized metering system that can accurately meter the amount of EARA and w ater. Interlock the pumps to the belt - weighing system that measures the quantity of RAP entering the mixing plant. Design the interlock so the EARA and water cannot be added until the RAP enters the mixer . Equip overrides of the interlock system with short duration timers to prevent their continuous use. The Engineer will allow the use of overrides only during startup periods. Provide reado uts on the belt -weighing device and computerized met ering system that show the quantity in tons of RAP , water, and EARA being fed into the mixer at any given time. Provide totalizer readouts to allow determination of accumulative quantities of each part.
d.EARA Storage Tanks. Make available accurate volume measuring devices or manufacturer's calibration charts and a thermometer for measuring the volume and temperature of the tank's contents. The Engineer wil l not allow solid or semisolid particles in the EARA in the final mix. Equip every line delivering EARA to the mix with an on/off valve and a changeable filter element. Change filters at the rate recommended by the manufacturer. Prevent detrimental effects to the recycled material due to interruption of the operation to change filters. The Engineer will reject loads of EARA that break prematurely in the storage tanks or haul vehicles or cause frequent plugging of the filters.
2.Cold milling . Cold mill the existing bituminous pavement to the depth specified. Do not damage the material below the plan depth of removal with the cold- milling operation. for Highway Construction Page 293 of 71 5 3. Mixing . The quantity of EARA added will be as necessary to fully coat all aggregate without filling voids with excess asphalt. Mix EARA at a rate between 1.5 to 3.0 percent by dry weight of cold - milled material as specified in the mix design. Add water to the cold- milled material to facilitate uniform mixing with the emulsified asphalt . Add water before or concurrently with adding the EARA. Continue mixing until the EARA and water have been distributed throughout the RAP to form a uniformly coated mixture. Ensure the temperature of the EARA before entry into the mixture is at least 90 ºF and less than 120 ºF.
4.Placing. Place the recycled material using a self -propelled bituminous paver . Except for unavoidable delay or breakdown, proceed with recycling and placing material by the paving machine at a rate sufficient to provide continuous operation of the paving machine. Cold mill and recycle no more of the roadway than what can be repaved in one day’s paving production. If recycling operations result in excessive stopping of the paving machine, suspend recycling and paving operations until the rate of recycle is synchronized with the capacity of the paving machine. Restrict placing operations to the pavement temperature of 50 ºF and rising. In addition, do not perform placing operations when it is anticipated that the atmospheric temperature will drop below 40º F within 48 hours of mixing, or when rain is expected. Ensure the final surface, including the shoulders, is within 3/8 inch from the bottom of a 10- foot straightedge laid in any direction on the surface on either side of the roadway crown. When tes ts show that the pavement is not within the specified tolerance, take immediate action to correct equipment or procedures in the paving operation to eliminate the unacceptable pavement irregularities. Correct surface deviations within 24 hours by reprocessing the surface, abrasive grinding or micro milling. Perform corrective work, including traffic control, at no additional cost to the Department. When a pick -up machine is used to feed the windrow into the paver hopper, pick up the entire windrow to the underlying material.
5.Compaction . Use compaction equipment and/or rolling methods to produce the required compaction without damaging the work, and the following:
a.Includ e in the compaction train at least one 10- ton minimum weight vibratory and one 25- ton minimum weight rubber -tired roller.
b.Provide compaction as specified in 405.03.O . The Department has divided the CIR layer into control strips and test sections. Each control strip is defined as an area of at least 400 square yards and of the same depth to be used in the test sections. Each test section is defined as an area 6,600 square yards or less. After 2 days of production, the test section size may be increased to a maximum of 13,000 square yards, if specified densities are being obtained. If any test section fails the density requirements , the 6,600 square yards maximum will again be used.
a.Construction of Control Strips. Construct control strips using the same procedures and on the same cold- milled material to be used in the construction of the rest of the work. Use the same type, mass, and sequence of rollers on the control strips as the tes t sections. for Highway Construction Page 294 of 71 5 Construct one control strip at the beginning of work of each roadway course . Construct an additional control strip when a change is made in the type or source of material or whenever a significant change occurs in the compaction of the material. The Engineer may require a new control strip after 10 test sections have been constructed without a new control strip. Compact the control strip. The required compaction is achieved and final process rolling is defined as when the final roller pass adds no more than 1 pound per cubic foot to the previous in-place density. Make sufficient additional roller passes to determine that a “false break” or leveling -off point is not used for com paction density. Upon completion of the rolling, The Engineer will determine the mean density of the control strip by taking 10 tests at randomly selected locations within the control strip area utilizing Test Method FOP for AASHTO T 355. The Engineer will govern compaction of successive test sections by the mean density obtained in the control strip. Leave approved control strips in pl ace to become a section of the completed roadway. The Engineer will subject control strips to the same surface tolerance requirements as the rest of the work.
b.Compaction Requirements of Test Sections. The Engineer will evaluate the density of each test section based on the results of 5 tests, performed at randomly selected locations within the test section as described in Test Method FOP for AASHTO T 355. The specified mean density obtained for the 5 tests is at least 98 percent of the mean density obtained in the approved control strip and each individual test value obtained is at least 95 percent of the mean density obtained in the approved control strip. If the mean density of a test section does not meet the 98.0 percent requirement continue the compactive effort on the entire test section until the required mean density is obtained. If an individual test value does not meet the 95.0 percent requirement, continue the compactive effort on the area represented by that test until the required density is obtained. Report density test results to the near est 0.1 percent.
c.Compaction Requirements for Small Sized Areas. In cases where the test section size cannot be as specified, the Engineer will accept compaction on the basis of a single test for every 1,000 square yards of area or less. The Engineer may adjust the specified individual test density to at least 95.0 percent of the mean density of the approved control strip.
6.Finishing. If segregation occurs in the windrow or behind the paver, the Contractor may be required to make changes in the equipment or operations. These changes may include the following:
a.Increasing the crushing effort.
b.Adjusting the amount of water in the mixture.
c.Adjusting or modifying the paver . The Engineer will accept cold recycled pavement visually after compaction. Correct mixture not acceptably mixed or that ravels. Reprocess areas showing an excess or deficiency of EARA or not acceptably mixed. If raveling occurs, provide additional rolling. If the Engineer determines the unacceptable material is due to the Contractor's operations, perform the corrective work at no additional cost to the Department. Before placing the initial lift of HMA, perform supplemental compaction when the moisture content of the recycled pavement is less than 2.0 percent by weight. Supplemental compaction is for Highway Construction Page 295 of 71 5 conducted using control strip and breakover compaction methods described above when the pavement surface temperature is at least 80°F.
430.04 Method of Measurement.
The Engineer will measure acceptably completed work as follows:
1.CIR pavement will be by the square yard. No separate payment will be made f or dust control or changes in equipment or operation due to segregation.
2.EARA will be by the ton.
3.Emulsified asphalt for fog coat will be as specified in 408.04.
4.Blotter will be as specified in 408.04.
5.Lime will be by the ton. The Engineer will use the dry weight to the nearest 0.01 ton incorporated in the work at the rate and in the quantity specified or directed. The quantity of lime will not include lost, displaced, used in reworking, used in restoration work, or used contrary to specifications or the Engineer’s direction. Water is incidental and included in the CIR pavement unit contract price.
430.05 Basis of Payment .
The Department will pay for accepted quantities as follows: Pay Item Pay Unit Blotter ..................................................................................................... Ton or CY Cold In -Place Recycled Pavement ......................................................... SY Diluted Emulsified Asphalt for Fog Coat ................................................. GAL Emulsified Asphalt Recycling Agent ...................................................... Ton Lime or Cement for Treated Recycled Pavement ................................... Ton for Highway Construction Page 296 of 71 5 SECTION 431 – COLD MILLING
431.01 Description.
Remove existing seal coat and plant mix pavement by cold milling to the widths and depths as specified or as directed. Transverse wedge milling will consist of cold milling a transverse wedge for the purpose of matching the profile grade of the wearing course to the lip of the gutter elevations.
431.02 Materials.
Not specified.
431.03 Construction Requirements.
Cold mill the pavement surface to the specified depths using sensing devices to control the depth and smoothness. Do not damage the bridge deck or approach slab and do not leave excess pavement in place. Taper cut ends to construct a ramp of 100H:1V slope. The ramp will consist of in -place, un- milled pavement . Square up the tapered area and mill to the specified depth and width before placing the new plant mix pavement. When milling operations create a situation where water cannot drain transversely off the roadway, create relief cuts or other approved methods to provide drainage. Sweep all loose material with pickup brooms. Prevent cold- mill tailings from being spilled or swept onto any lane used by traffic. Some handwork may be required at certain locations (e.g., manholes, inlets, valve boxes, meter boxes, street monuments ). Mill a consistent straight line to the Engineer’s satisfaction. Provide a power -operated, self -propelled milling machine that is capable of automatically and accurately establishing profile grades along each edge of the machine within 0.01 foot (vertical) by reference from the existing pavement by means of a 20- foot minimum ski or from an independent grade control. The equipment will be controlled by an automatic system for controlling depth and cross -section at a given cross slope rate. A 10 -foot ski for cold- milling profile grade control may be used, if approved. A 10- foot ski for cold- milling profile grade control is not allowed on bridge deck areas. Use a mill with a tooth spacing of 5/8 inch or less. The surface texture depth will not be greater than 0.6 inch. The Contractor will use a fine head mill with tooth spacing of 1/4 inch or less for all milling on bridge deck s or areas where traffic will be driving over the surface for more than 3 days. Provide a machine capable of controlling dust and other particulate matter created by the mill cutting act ion. Do not use a heating device to soften the pavement . The texture produced by cold milling will be a grid pattern with uniform striations or other patterns that will provide optimum conditions for placement of plant mix pavement . Construct a 100- foot long test section showing the machine is capable of meeting these requirements.
Source: Idaho Standard Specifications for Highway Construction, 2023 Edition. Pages 326–331 of 768.