320 Page 156PART C ASPHALT CONSTRUCTION
320.1DESCRIPTION
These requirements are applicable to all types of hot mixed asphalt pavements irrespective of class, type, asphalt material, or pavement use. Exceptions to the general requirements are in the specified requirements for each class. The work consists of one or more courses of asphalt concrete mixture constructed on a prepared foundation.
320.2MATERIALS
A.Composition of Mixtures: The asphalt concrete will be composed of a mixture of aggregate, asphalt binder, additives, and approved modifiers. Unless otherwise specified in the plans, no RAP is allowed in the asphalt concrete. Aggregate fractions will be combined in proportions resulting in a mixture meeting the specified requirements. The operation of the plant will not commence until the Department’s Bituminous Engineer has established or verified a job mix formula, in writing, meeting the aggregate and mix design specification requirements for the class and type of asphalt concrete specified. The job mix formula established or verified by the Department’s Bituminous Engineer will fix a single percentage of aggregate passing each required sieve size, a single percentage of asphalt binder to be added to the aggregate, a single asphalt binder application temperature at the mixer, a single temperature at which the mixture is to be discharged from the mixer, and a single temperature at which the mixture is to be delivered to the road. The following table sets forth the tolerances for the job mix formula: Gradation, percent passing, sieve sizes 3/8 inch & larger ........................................................................................... ±7 #4 thru #40................................................................................................... ±5 #200 .......................................................................................................... ±2.0 Percent asphalt binder content ....................................................................... ±0.3 Percent hydrated lime content ...................................................................... ±0.10 Temperature of mixture when emptied from mixer ....................................... ±20°F Temperature of mixture on delivery to the road .............................. -20°F & +30°F Asphalt binder application temperature ........................................................ ±20°F Percent RAP content (if used) ............................................................................ ±5 Job mix formula tolerances for Class Q asphalt concrete will conform to Section 322. The mixture will conform within the range of tolerances established by the job mix formula for that class of asphalt concrete. Should a change in sources of materials be proposed or when unsatisfactory results are obtained, a new job mix formula will be established. Blade laid asphalt concrete mixture will consist of the fine aggregate components of the asphalt concrete class specified on the project. The job mix formula established or verified by the Department’s Bituminous Engineer will set the fines components at approximately the 320 Page 157same proportions as the asphalt concrete class specified on the project and will fix a single percentage of asphalt binder to be added to the aggregate, a single asphalt binder application temperature at the mixer, a single temperature at which the mixture is to be discharged from the mixer, and a single temperature at which the mixture is to be delivered to the road. The blade laid asphalt concrete mixture may contain a small amount of coarse aggregate (+#4 sieve). The Department will not perform quality testing on any of the coarse aggregate (+#4 sieve) in the blade laid asphalt concrete mix. B.Aggregates: Aggregates will conform to Section 880. C.Asphalt Binder: Asphalt binder will conform to Section 890. D.Shoulder Joint Sealant: Joint sealant will conform to Section 870. E.Additives: An additive is any material added to a bituminous mixture or material including, but not limited to; mineral filler, warm mix asphalt additives, asphalt additives, and similar products without a specific pay item. Additives will not be incorporated into the mixture without approval of the Department’s Bituminous Engineer. F.Hydrated Lime: Hydrated lime will conform to Section 760.
320.3CONSTRUCTION REQUIREMENTS
A.Weather and Seasonal Limitations: Asphalt concrete will not be placed when the underlying surface is wet or frozen. Asphalt concrete will not be placed when weather conditions prevent proper handling, compaction, or finishing. The temperature and seasonal limitations are as follows: MINIMUM AIR TEMPERATURES & SEASONAL LIMITATIONS Surface CourseSubsurface Course & Shoulder Course Compacted Thickness Minimum Temperature*1Seasonal Limits Minimum Temperature*1Seasonal Limits 1 inch or less 45°FMay 1 to Oct. 15 (inclusive)45°F none over 1 inch 40°FMay 1 to Oct. 15 (inclusive)40°F none *1Minimum air and surface temperature in the shade. B.Equipment: 1.Requirements for All Plants: The central plant for mixing the aggregate and asphalt binder may be a batch or drum mix type mixing plant. Stockpiles of aggregate will be kept separate and adequate measures to prevent contamination must be used at stockpile sites. Contaminated piles will be rejected. Segregated piles will be rejected until corrected. 320 Page 158When mineral filler, hydrated lime, or other additives are required, a separate feed system will be provided to store and accurately and uniformly proportion the required quantity into the mixture. All cold feed bins will be equipped with dividers to prevent overflow of aggregate to adjacent bins. The plant will be equipped with emission control equipment including a dust collector capable of eliminating or conserving the dust necessary to meet gradation limits and environmental standards. Burner fuel used for production of asphalt concrete will be propane, butane, natural gas, Grade 1 fuel oil, Grade 2 fuel oil, Grade 4 fuel oil, Grade 4 (light) fuel oil, Grade 5 (light or heavy) fuel oil, or Grade 6 fuel oil. Fuel heavier than Grade 2 will meet the requirements of ASTM D396. Recycled fuel oils, RFO4, RFO5L, and RFO5H may also be used provided they meet the requirements of ASTM D6448. The burner fuel supplier will certify each load of burner fuel meets the applicable ASTM specification. Recycled fuel oils and fuel oils heavier than Grade 2 will be properly preheated and efficiently burned. Production of mix will be stopped if flameouts or signs of incomplete combustion occur. A pyrometer or other thermometric instrument will be installed in the supply line between the asphalt binder storage tank and the asphalt binder discharge point in the plant to accurately measure the temperature of the asphalt binder. An in-line sampling valve will be installed in the supply line between the asphalt binder storage tank and the asphalt binder discharge point in the plant. The plant will be equipped with accurate weighing or volumetric measurement devices. Asphalt binder storage tanks will be kept level. Accurate calibration charts which show the quantity of material contained in a tank at each 1/4 inch increments of depth and a suitable device to measure the depth of the material will be provided. Storage tanks will uniformly heat the material, under effective and positive control, to the required temperature. Heating will be accomplished by steam coils, electricity, or burners, provided the flame does not come in direct contact with the heating tank. The asphalt circulating system will be of adequate size to ensure proper and continuous circulation during the entire operating period. An accurate thermometer must be installed in the tank so the temperature can be monitored. When hydrated lime is used, the Contractor’s hydrated lime system will be equipped with scales to accurately determine the amount of hydrated lime used at any time. The Contractor’s hydrated lime system will control fugitive lime dust from being released into the air. Hydrated lime, when added, will be added at the pugmill to moistened aggregate containing a minimum moisture content of 1.0% above the saturated surface dry condition of the aggregate, as noted on the approved job mix formula. The mixing of the aggregate, hydrated lime and water will be accomplished by using an enclosed twin-shaft pugmill with a minimum effective length of 4.5 feet. A water spray system must be installed at the 320 Page 159discharge end of the pug mill. This water system must be used when directed by the Engineer to prevent fugitive lime dust from being released into the air. 2.Batch Type Mixing Plants: Batch type plants will have at least two storage bins with sufficient capacity to furnish the quantity of mineral aggregate materials necessary to operate at the calibrated capacity of the plant. Each compartment will have partitions to prevent diversion of material into other compartments. Vibrators will be provided to prevent bridging or arching of the bin contents. Batch plants will be fully automatic, to the extent the only manual operation required would be for the proportioning of one batch utilizing a single actuation switch or starter. The automatic unit will include a timer to automatically control the measuring, mixing, and dumping processes through a central control. The automatic unit will include a time lock device, capable of controlling the operations of a complete mixing cycle. When RAP is used, batch plants will be modified to permit the RAP to feed directly into the weigh hopper of the plant. When RAP is used, the heated virgin aggregate will be deposited in the weigh hopper first followed by the RAP. These two materials will be “dry” mixed for a minimum of 10 seconds before introduction of asphalt binder into the pugmill. Wet mixing time will be a minimum of 25 seconds. Mixing times may be adjusted by the Engineer, as necessary, to achieve uniform mixing and coating. Discharge of the heated virgin aggregate will be from one bin only and will be discharged into the center of the weigh hopper. The amount of aggregate stored in the bin will not exceed one batch in weight and will be fed into the bin in a manner that will prevent segregation. A recording pyrometer will be mounted in the discharge chute of the dryer. Daily charts of continuous aggregate temperature readings will be submitted to the Engineer. In lieu of a recording pyrometer, a computer printout showing the aggregate temperature readings at the discharge chute of the dryer may be substituted as approved by the Engineer. 3.Drum Mix Plants: The dryer drum will uniformly heat, coat, and mix the materials without overheating the materials and adversely affecting the mixture. a.Materials and additives, except RAP, will be fed simultaneously into the dryer. b.The aggregate and RAP feed system will be easily and accurately calibrated and will provide positive control of the aggregate feed. The rate of feed will be continuously monitored by belt scale or other device interlocked with the asphalt metering mechanism. c.RAP, when used, will be introduced into the drum and combined with the aggregate so the RAP does not come into direct contact with the burner flame. Asphalt binder will be added to the mixture in the drum after the aggregates and RAP have been combined. 320 Page 160d.The asphalt metering device will positively control the rate asphalt is introduced into the mixture and will respond instantaneously to variation in the aggregate feed rate. e.Production will be limited to the rate required to obtain uniform aggregate coating and a uniform mixture meeting job mix temperature requirements. The rate must be within manufacturers rated plant capacity. f.A recording pyrometer will be mounted in the discharge end of the mixer for determining the temperature of the mix. Daily charts of continuous mix temperature readings will be submitted to the Engineer. In lieu of a recording pyrometer, a computer printout showing the mix temperature readings at the discharge end of the mixer may be substituted as approved by the Engineer. 4.Blade Laid Asphalt Concrete Equipment: The Contractor will use either a motor grader blade or a paver to perform the blade laid asphalt concrete work. The equipment will force the mixture into the joints and cracks to adequately level and fill the joints and cracks while not exceeding the required application rate. If the Contractor uses a motor grader blade, the blade will be equipped with gates, wings, or other devices approved by the Engineer to prevent the material from windrowing at the edges of the blade. If the Contractor uses a paver, the paver will be equipped with a solid screed bar plate measuring a minimum of 12 inches wide by 1.5 inch thick. Self-propelled pneumatic tired rollers will cover an overall surface width of at least 60 inches and will furnish a minimum rolling weight (mass) of 250 pounds per inch of roller width. 5.Pavers: Self-propelled pavers will be equipped with a hopper having a bottom conveyor, a full width vibrating screed with heaters and augers, and will be capable of spreading and finishing the mix to the specified widths, typical section, and thickness. Hydraulic extendable screeds may be used for variable width pavements. Auger extensions will be used as recommended by the paver manufacturer and will extend to within 12 to 18 inches of the edge of the paver screed. The paver will provide an accurate, smooth, and uniform textured spread and will provide preliminary compaction. An attachment will be provided on the paver that will place a beveled edge on the mat as specified. Pavers will be equipped so that the height and transverse slope of the screed is automatically controlled using a fixed or traveling stringline on either or both sides of the paver. The traveling stringline will utilize either mechanical skis or non-contacting grade averaging sensors. The traveling stringline will have a minimum effective length of 25 feet. The system will be capable of manually controlling the transverse slope and screed height. 6.Rollers: Rollers for compacting the asphalt concrete will be of the self-propelled type, capable of producing a smooth surface finish. The number and weight of rollers furnished 320 Page 161will be sufficient to compact the mix to the required density. The rollers will be capable of being reversed smoothly, without shoving or tearing the asphalt concrete. Rollers will be equipped to prevent "pickup" on the tires or drums. Moistening the drums or tires with water, a water detergent solution, or enclosing the roller to prevent heat loss from the tires may be required. The use of fuel oil or other petroleum solvents to prevent "pickup" will not be permitted. Measures will be taken to prevent oil, grease, or fuels from being dropped on the mat by rollers or any other type of equipment. C.Preparation of the Mineral Aggregate: 1.Stockpiling Aggregate: Stockpiles of mineral aggregate for asphalt concrete will be built in layers, completing each layer over the full area of the pile before the next layer is started. The height of each layer will be controlled to minimize segregation. The maximum drop of the materials from the conveyor will not exceed 10 feet. Coning will not exceed 10 feet. The stockpile will be leveled with rubber tired equipment between layers to maintain a level platform for the next layer. Dumping, casting, or pushing over the sides of the previous layers will not be permitted. Segregated piles will be rejected until corrected. The equipment operating on the pile will be free of dirt, grease, oil, and other contaminants. The size of the equipment will be limited to that which can be operated on the stockpile without degradation of the material. The leveling requirement will be waived for the fines stockpile when split on a 1/4 inch or smaller screen unless there is indication of segregation. Aggregate stockpiles will be kept separate and adequate measures to prevent contamination must be used at stockpile sites. 2.Stockpile Tests: The Contractor will run process control tests on the mineral aggregate when producing material. A gradation, PI, fractured faces, and lightweight particles test will be run for every 1500 tons produced per pile. The Contractor will also test the quality (abrasion and soundness) of the mineral aggregate. The quality will be tested once per source. All sampling and testing will be accomplished in accordance with the Department’s Materials Manual. The Engineer may reduce the frequency of the stockpile tests on ledge rock sources depending on the quality and uniformity of the materials. Test results will be recorded on forms furnished by the Department and will be immediately submitted to the Engineer. 3.Mix Design Submittal: The asphalt concrete mix designs will be performed by the Department's Bituminous Mix Design Lab. Prior to submitting samples to the Department’s Bituminous Mix Design Lab, 50% of the plan quantity or 15,000 tons whichever is less, of the mineral aggregate will be produced. When RAP is required, the Contractor will sample the RAP from the roadway by an approved method. The sampling method will ensure a representative sample of material is obtained from approximately the same depth as the plans shown milling depth. The RAP sample will be obtained from a minimum of three locations throughout the project length. The Contractor will daylight all edges of the sampling area leaving no vertical faces or will fill the sample area with an approved product leaving no vertical faces. The equipment used will generate a representative sample of RAP similar to what will be produced from the cold milling operation. The Contractor will notify the Area office a minimum of 5 calendar days prior to sampling the RAP from the roadway. A representative from the Area office will witness all sampling of RAP to be submitted for 320 Page 162mix design. This material will be used to perform the mix design. A portion of this sample will be submitted to the Department’s Bituminous Mix Design Lab. The Contractor will notify the Area office a minimum of 5 calendar days prior to sampling and submitting the mix design aggregates. A representative from the Area office will witness all sampling of aggregates to be submitted for mix design. A representative from the Area office will complete the Form DOT-1 for the composite aggregate sample and RAP sample required for submittal to the Department’s Bituminous Mix Design Lab in Pierre, SD. The Area office representative will take possession of the aggregate and RAP samples for mix design and aggregate quality testing. Samples will be obtained a minimum of 21 calendar days prior to hot mix production. The Department will deliver the samples to the Department’s Bituminous Mix Design Lab. The Department may allow the Contractor to transport and deliver the RAP and aggregate samples for mix design and aggregate quality testing only when the Area office representative has sealed the samples with a tamper evident tag, with the DOT-1 attached. Mix designs will only be performed on samples when accompanied by the following information: a.A completed data sheet (DOT 1), including the legal description of all mineral aggregate sources. b.The mineral aggregate and RAP samples submitted will be representative of the materials produced for the project. c.The average stockpile test results of each mineral aggregate stockpile produced along with the recommended bin splits of each material produced. d.A 1-gallon sample of asphalt binder intended for use will be obtained from the designated supplier for the project. e.A temperature viscosity curve (chart) or required mixing temperature for the asphalt binder intended for use and the specific gravity of the asphalt binder. The asphalt binder supplier will provide the recommended lab mixing and compacting temperatures and the recommended field mixing and compaction temperatures for modified asphalt binders. Two mix designs per type will be made by the Department without charge. Should the Contractor desire an additional mix design, or if additional mix designs are required due to the materials not meeting specifications, the costs involved will be at the Contractor’s expense. 4.Proportioning of Aggregates: If blending of aggregates is required, separate bins and stockpiles will be provided. Materials will be kept separated until they are delivered in their proper proportions onto the feeder leading to the dryer. Spreading or dumping filler, sand, or crushed rock over the top of gravel pits, stockpiles, or in hoppers at the crushing plants 320 Page 163will not be permitted. Charging bins directly from pits, crusher, or screening plants will not be permitted. The mineral aggregate exclusive of other additives will be separated into at least two fractions dividing on the #4 sieve or other size agreed upon and placed into separate compartments ready for proportioning and mixing. D.Preparation of the Mixture: The mineral aggregate will be satisfactorily mixed with the proper quantity of asphalt binder at the central mixing plant. The mixing plant will be operated using automatic controls. Manual operation will be permitted for the remainder of the day when automatic controls fail, provided specified results are obtained. The Contractor will restore automatic operation prior to the next day's production. The asphalt binder will be added to the mix in the proportionate quantity and at the temperature established by the job mix formula. In batch plants, the mineral aggregate will be mixed dry for a minimum of 5 seconds. After introducing the required aggregate and asphalt binder into the mixer, the materials will be continuously mixed until the aggregate is completely and uniformly coated and a thorough distribution of the asphalt throughout the aggregate is obtained. Mixtures containing incompletely coated particles at the time of discharge from the plant or thereafter will be rejected. The Contractor will make appropriate adjustments in the production of mixtures to ensure the mixture is completely coated at the time of discharge from the plant. When hot mix storage bins are used, storage of the mix will be limited to a maximum of 15 hours. The point of temperature measurement will be the discharge end of the mixer. E.Transportation and Delivery of the Mixture: The mixture will be transported from the plant to the point of use in pneumatic tired vehicles. The vehicle boxes will be tight, clean, and smooth. Boxes will be cleaned only with lime water, soap, a detergent solution, or an approved commercial product specifically intended for this use. Oil, diesel fuel, or other petroleum solvents will not be used. No material will be used which could adversely affect the asphalt concrete. Excess solution in the box will be disposed of before the vehicle is loaded. The Contractor will cover the loads with a tarp during inclement weather conditions and when ordered by the Engineer. Tarps will be of sufficient condition to protect the load from infiltration by rain, snow, dust, and other foreign matter and to slow the loss of heat. The Engineer, in the Engineer’s discretion, will determine the acceptability of the condition of the tarp. F.Blade Laid Asphalt Concrete: Prior to placing the blade laid asphalt concrete mix, the Contractor will thoroughly sweep the surface to remove all loose existing joint material and loose asphalt concrete from cracks, joints, and spall areas. In curb and gutter sections or in rural sections where a finished and maintained lawn extends to the edge of the shoulder, the Contractor will use a pickup broom with an integral self-contained storage. The pickup broom must be a minimum of 6 feet wide. While sweeping in curb and gutter sections, the sweeping 320 Page 164operation must remove all loose material, including loose material from the gutter. A rotary power broom may be used in all other locations. The blade laid asphalt concrete mix will be compacted by at least two complete coverages with self- propelled pneumatic tired rollers. G.Tacking, Spreading, and Compacting: The surface, including all vertical contact faces, on which the asphalt concrete is to be placed, will be tacked in accordance with Section 330. The tack coat will be allowed to break (turn from brown to black) and will be allowed a cure period, as determined by the Engineer, prior to asphalt concrete placement. Surfaces which have been primed with cutback asphalt will be allowed to cure for a minimum of 72 hours prior to being overlaid with asphalt concrete. Asphalt concrete will be placed by self-propelled pavers. Handwork is permissible in inaccessible or odd shaped areas. In lieu of a self-propelled paver, asphalt concrete may be placed by a shouldering machine on shoulders less than 6 feet in width. Spot leveling and repair of the existing surface with asphalt concrete will be required prior to the paver laid courses at locations designated. Potholes and areas of localized disintegration will be cleaned of loose material, squared, tacked, leveled with asphalt concrete, and satisfactorily compacted. Spot leveling may be blade laid in lifts not exceeding 3 inches of uncompacted depth. Compaction will be by the specified roller coverage method. The Contractor may use a steel face roller provided the roller does not damage the mineral aggregate during compaction. Paver laid mix will be spread using automatic transverse and longitudinal grade controls. If the automatic controls fail or malfunction, the Engineer may permit manual operation for the remainder of the day, provided the finished product meets the specifications. Frequent breakdowns will constitute cause for suspension of the work until repair or replacement is made. Following placement of the first pass using the traveling stringline for control, adjacent passes and succeeding lifts will be placed using the traveling stringline riding on the previously laid material. A shoe attachment may be used to match the longitudinal joint(s) on the final paver pass(es) of the top lift unless otherwise directed by the Engineer. A shoe attachment on the paver will be used to automatically match the elevation of asphalt concrete shoulders with concrete pavements. Automatic slope controls will be required on paving equipment for placing asphalt concrete on shoulders, 8 feet or more in finished width. Asphalt concrete will be placed directly on the roadbed in a uniform windrow and then fed into the paver by a paver feeder. The use of a paver feeder is not required on shoulders, turning lanes less than 500 feet roadway paving less than 500 feet and transitions into bridge decks less than 500 feet. The paver feeder will pick up substantially all of the mix and feed it into the paver without segregation. The size of the windrow will be regulated so the paver is fed a continuous and adequate supply of mix. The screed will not be raised solely to accommodate excess material in the windrow or paver hopper. A Material Transfer Vehicle 320 Page 165(MTV) which takes material directly from the trucks, stores and mixes it, and then dumps into the paver hopper may be used if approved by the Engineer. The "temperature of mixture on delivery to the road" will be defined as the temperature of the mix just prior to placement or just prior to spreading by blade. On the final surfacing lift, laydown operations may progress continuously toward or away from the plant. If the Engineer, in the Engineer’s discretion, determines damage to the top mat is occurring, the Engineer may require laydown operations to commence from the farthest point and progress continuously toward the plant. On rural projects, a partial width pass may be extended beyond the adjacent pass by as much as one day's run. The paver will be moved back the following working day to place the adjoining pass. Where a difference in elevation exists between two lanes carrying traffic in the same direction on rural multilane asphalt concrete construction, one of the affected lanes will remain closed to traffic. The plant production and availability of hauling vehicles will be sufficient to provide a uniform and consistent quantity of asphalt concrete to the paver, so laydown operations are continuous. Stops and starts will be restricted to a minimum and excessive stopping of the paver will result in suspension of paving activities until corrective measures are taken. Stopping normal laydown operations to surface an approach, thereby creating an unnecessary joint, will not be permitted. Laydown operations will proceed from the center to the shoulders of the roadbed surface. When turning lanes are present, the Contractor may alter the laydown operation. In curb and gutter sections, laydown may proceed from the gutter line to the centerline. The Contractor will submit the proposed laydown operation to the Engineer for approval prior to beginning laydown operations. The longitudinal joints of succeeding lifts will be offset approximately 6 inches. The center longitudinal joint of the top lift will be located on centerline except where a center turning lane is present. Longitudinal joints will be located within 12 inches of the lane line. At the end of the day’s paving, the Contractor will place a temporary ramp from the top of the lift of asphalt concrete to the existing surface. The temporary ramp will extend a minimum of 3 feet per 1 inch of asphalt concrete placed. Transverse joints of the final lift will be formed by sawing back the previous run to expose the full depth of the course. The finished transverse joint of all lifts will have a uniform texture and comply with the straightedge requirement. Waste material resulting from forming joints and temporary ramps will be removed and disposed of. Segregation or excessive pulling of the mix will warrant suspension of operations. Immediately after the mix has been placed and surface irregularities adjusted, the mix will be thoroughly and uniformly compacted by rolling. Multiple lift laydown operations will not be allowed on the same location on the same day unless approved by the Engineer. The use of ice or other materials to accelerate the cooling of the lift will not be allowed. 320 Page 166Vibratory rollers will have an automatic shutoff to deactivate the vibrators when the roller speed is less than 0.5 mph Rollers will be operated according to the manufacturer’s recommendations for speed, impacts per foot, and amplitude of vibration for the thickness of mix being compacted. Rolling will be longitudinal, commencing at the outer edges of the mat and progressing toward the center in straight, parallel strips, overlapping at least 6 inches. On superelevated curves, rolling will progress from the lower to the upper edge of the mat. The Contractor will vary the points of reversal to prevent a transverse crease. The rollers will not stand idle on any part of the mat that has not been completed and cooled sufficiently to resist deformation. Class Q asphalt concrete placed on the shoulder will be compacted using the same roller pattern used on the adjacent mainline asphalt concrete or as directed by the Engineer. The beveled edge will be satisfactorily compacted and will retain the specified dimensions after compaction. Longitudinal joints will be compacted in accordance with the following: For confined edges, on the first pass adjacent to the confined edge, the compaction equipment will be entirely on the hot mat 6 to 12 inches from the longitudinal joint. For unconfined edges, on the first pass adjacent to the unconfined edge, the compaction equipment will extend 4 to 6 inches beyond the edge of the mat. The surface of each lift will be free of waves and other irregularities. The final lift surface will be checked with a 10-foot straightedge. The variation of the surface from the straightedge between any two contact points will not exceed 1/4 inch. The crown, on all lifts, as indicated by checking with a 10-foot straightedge, will be within 0.04-feet of specified crown in any 10-foot length. Irregularities will be corrected before the temperature of the asphalt mix drops below 175°F. The longitudinal profile can only be improved by using a grinder with diamond blades mounted on a horizontal shaft and when approved by the Engineer. Areas that have been ground will not be left smooth or polished but will have a uniform texture similar in roughness to the surrounding unground asphalt concrete. Grinding will be day lighted to the outside edge of the pavement. Ground surfaces will be flush sealed. Under no circumstances will operations continue when it becomes evident final rolling is not producing a smooth, uniform, compacted surface free from roller marks and other irregularities. The mix will be compacted on the road by one of the following methods. Unless otherwise specified, the Specified Density Method will be used. 1.Specified Density Method: The mix will be compacted to the density specified for the class of asphalt concrete designated. The lot average percent of density will be based on the maximum specific gravity of the test specimens prepared in the field in accordance with SD 312. The lot will contain no more than 2 tests below the specification, no more than 1 test 2% below the specification, and no test 3% or more below the specification. The compacted density of asphalt concrete will be determined according to SD 311. 320 Page 167Compaction rolling will be completed before the temperature of the mix drops below 175°F. Vibratory rollers may be used in the static mode for finish rolling. Compaction of mix placed on entrances to farms, residences, or businesses and intersecting road approaches will be compacted by the specified roller coverage method. 2.Specified Roller Coverage Method: The mix will be compacted by at least four complete coverages with pneumatic tired rollers and at least one complete coverage with steel faced rollers, or as approved by the Engineer. Self-propelled pneumatic tired rollers will cover an overall surface width of at least 60 inches and furnish a minimum rolling weight (mass) of 250 pounds per inch of roller width. Self-propelled tandem smooth steel rollers (two steel drums operating in the same track) will furnish a minimum rolling weight (mass) of 325 pounds per inch of roller width. Breakdown rolling may be accomplished by steel-faced rollers, only when approved by the Engineer. Rolling will proceed on the mat as soon as lay down is completed. Completion of rolling on any segment will not lag behind the laydown more than 1000 feet. During periods of cool weather this maximum distance between laydown and final rolling will be reduced as ordered by the Engineer. Compaction to a specified density will not be required. However, additional roller coverage may be required in order to obtain a smooth surface finish. H.Maintenance: The Contractor will maintain the work during construction and until the Acceptance of Field Work is issued by the Area Office. Maintenance will include protection and repair of the prepared base course, tack coat, wearing surface mat, shoulders, and seal course. Rich or bleeding areas, breaks, raveled spots, or other nonconforming areas in the wearing surface or base will be corrected. I.Traffic Control: Hauling or allowing traffic on the roadway will not be permitted until the surface has been compacted and cooled sufficiently to resist marking or distortion. Where traffic is to be maintained by means of part width construction, the Contractor will control all traffic by identified pilot cars and flaggers. The Contractor will schedule work so traffic will not be greatly inconvenienced with long one-way lanes. J.Compaction Sample: When ordered by the Engineer and at locations designated by the Engineer, the Contractor will saw and remove a compaction sample in accordance with SD 311. After removal, the Contractor will repair the sample location to the satisfaction of the Engineer. The Engineer will take immediate possession of all samples for further testing. K.Shoulder Joints : When specified, a continuous groove will be constructed by forming, sawing, or routing the joint between the Portland cement concrete pavement and the asphalt concrete shoulder. Sawing may be done with either diamond or water-cooled abrasive blades. 320 Page 168If a router is used the router must be mechanical, power driven, and capable of cutting a groove to the required dimensions. Equipment designed to plow the groove to dimension will not be permitted. The walls of the finished groove will be vertical, and the groove bottom will be flat. The groove will be thoroughly cleaned immediately after forming, sawing, or routing. Dry sawed joints will be cleaned with high-pressure air. Wet sawed joints will be cleaned with high-pressure water followed by high-pressure air. The air compressor will produce a minimum of 125 CFM output and will be equipped with a maximum 3/4 inch nozzle. The groove (including the sides) will be free of dirt, dust, water, oil, grease, and loose material immediately prior to sealing. The Portland cement concrete surface will be free of asphalt and any curing compound that would prevent bonding. The groove will be completely dry and filled level with joint sealer by a sealing device, which will not entrap air in the sealed joint. Joint sealer application will not be permitted when the air temperature near the joint is less than 40°F or is 40°F and falling.
320.4METHOD OF MEASUREMENT
A.Asphalt Binder: Asphalt binder will be measured to the nearest 0.1 ton. Quantities of asphalt binder in excess of the asphalt content listed on the job mix formula plus the 0.3% tolerance will not be accepted for payment. B.Asphalt Concrete: Asphalt concrete will be measured to the nearest 0.1 ton for the class specified. The mixture of mineral aggregate, asphalt binder, and hydrated lime, when required, will be weighed after mixing. No deduction will be made for the weight of the asphalt binder or hydrated lime, when required, included in the mixture. Deduction will not be made for material removed from temporary approaches authorized by the Engineer. C.Compaction Sample: Compaction samples will be measured by actual count of compaction samples ordered and accepted by the Engineer. D.Sawing and Sealing Shoulder Joints: Field measurement for this work will not be required. Plan quantity will be the basis of payment. If changes are ordered by the Engineer, the length will be measured to the nearest foot and the quantity adjusted. E.Hydrated Lime: Hydrated lime, when provided as an additive to the asphalt concrete mixture to meet the moisture sensitivity requirements, will be measured to the nearest 0.1 ton. Quantities of hydrated lime in excess of the lime content listed on the job mix formula plus the 0.10% tolerance will not be accepted for payment. F.Stockpile Tests: Stockpile tests will not be measured for payment.
320.5BASIS OF PAYMENT
A.Asphalt Binder: The accepted quantities of asphalt binder will be paid for at the contract unit price per ton. 320 Page 169B.Asphalt Concrete: The accepted quantities of asphalt concrete will be paid for at the contract unit price per ton complete in place. C.Compaction Sample: Compaction samples will be paid for at the contract unit price per each. Payment will be full compensation for all labor, equipment, materials, and all other items incidental to sampling and repair of the sample locations to the satisfaction of the Engineer. D.Sawing and Sealing Shoulder Joints: Sawing and sealing shoulder joints will be paid for at the contract unit price per foot. E.Hydrated Lime: Hydrated lime will be paid for at the contract unit price per ton complete in place. Payment for hydrated lime will only be made when hydrated lime is actually used. F.Stockpile Tests: There will be no direct payment for the stockpile testing and related requirements. All costs related to the testing for labor, test equipment, laboratory, tools and all incidentals required to satisfactorily perform the required work will be incidental to the asphalt concrete pavement items. 321 Page 170321 ASPHALT CONCRETE – CLASS D, E, G
321.1DESCRIPTION
This work consists of constructing one or more courses of asphalt concrete on a prepared surface.
321.2MATERIALS
The materials and their use will conform to Section 320.2 .
321.3CONSTRUCTION REQUIREMENTS
The construction requirements will be as prescribed in Section 320.3 with the following modifications: A.Mix Design Specifications: Unless otherwise specified in the plans, the mix design criteria will conform to the following requirements for the class and type of asphalt concrete specified. MIX DESIGN SPECIFICATIONS MIX DESIGN PARAMETERS Class D Class E Class G % Air Voids 4.0 Min. 4.0 Min. 4.0 Min. % VMA*1 3/4 inch nominal maximum size 13.5 Min. 13.5 Min. 13.5 Min. 1/2 inch nominal maximum size 14.5 Min. 14.5 Min. 14.5 Min. Gyratory Gyrations 40 50 60 Dust/Binder Ratio (based on effective binder) 0.6-1.4 0.6-1.4 0.6-1.4 Moisture Sensitivity*2NA NA 70 Min. *1Evaluated for compliance during the mix design. If the percent passing the 1/2 inch sieve is greater than or equal to 90% the mix will be considered 1/2 inch nominal maximum size. If the percent passing the 1/2 inch sieve is less than 90% the mix will be considered 3/4 inch nominal maximum size. Mixes containing 80% or more limestone ledge rock will meet the VMA requirements of 13.0% Min. for a 3/4 inch nominal maximum size and 14.0% Min. for 1/2 inch nominal maximum size. *2Moisture sensitivity will be tested according to SD 309. Hydrated lime will be used to meet the moisture sensitivity requirement of the mix. Hydrated lime will not be required if the moisture sensitivity requirements are met without the addition of hydrated lime. Hydrated lime will be included in the dust (-#200)/binder ratio. B.Thickness: The compacted thickness of each lift will not exceed 3 inches. C.Density: The lot average minimum density requirement will be 92% of the maximum specific gravity of the test specimens prepared in the field in accordance with SD 312. The lot will contain no more than 2 tests below the specification, no more than 1 test 2% below the specification, and no test 3% or more below the specification. The compacted density of asphalt concrete will be determined according to SD 311.
321.4METHOD OF MEASUREMENT
Measurement as prescribed in Section 320.4 .
321.5BASIS OF PAYMENT
Payment as prescribed in Section 320.5 .