- 314 - SECTION 503 -- ASPHALTIC CONCRETE
503.01 Description
1.This work shall consist of producing and placing asphaltic concrete as shown in the contract.
503.02 Material Requirements
1.Asphaltic concrete shall conform to the requirements in Section 1028.
2.Performance Graded Binder (PG Binder) shall be the type and grade specified in the contract and shall conform to the requirements in Section 1029.
3.The PG Binder used in the Stat e maintenance patching shall be the same type used in the asphaltic concre te mixture that is being produced at the time the patching material is procured.
503.03 Equipment
1.General Requirements:
a.The Contractor shall provid e plant calibration documentation.
b.Tank volume values shall be available at the plant.
2.Asphaltic Concrete Mixing Equipment:
a.General Requirements: (1) The equipment that is us ed for heating, proportioning, and mixing the aggregates and PG Binder shall be able to produce a uniform mixture.
2.The dryers shall be able to dry and heat all aggregates to the required temperatures with positiv e control. Aggregates shall be agitated continuously during the process of he ating. Damage to PG Binder in dryer- drum type mixing plants shall be avoided.
3.Recycled Asphalt Pavement shall not be exposed to open flame.
4.Continuous temperature and time readings of the asphaltic materials shall be electronically recorded whenever the plant is operated. A daily copy of the temperature reco rds shall be given to the Engineer. Temperature and time displays shall be easily accessible. Temperature and time sensors will be provided at the following locations:
i.Inside the asphaltic concrete mixture discharge chute. (ii) Inside the surge bin. (The Contractor may manually take and record the temperature. Readings will be taken every 2 hours when the plant is in operation.) (iii) Inside the PG Binder storage tank. (Readings shall be taken every 2 hours when the plant is in operation.)
5.(i) Equipment used for heating PG Binder shall conform to the requirements of Section 501. (ii) During storage, t he PG Binder temperature shall be maintained in accordance with binder supplier recommendations. All plants shall be equipped with a circulating system which is designed to assure proper and continuous circulation of the PG Binder during the operating Asphaltic Concrete 503.03 - 315 - period. Storage tanks shall have suffici ent capacity to provide for continuous operation. The tanks shall be situated and constructed to allow the volume of the PG Binder to be safely and accurately determined at any time.
6.(i) The plant may have surge bins for the temporary storage of asphaltic concrete. (ii) The asphaltic concrete taken from the surge bin shall not differ from the material taken directly from the plant. (iii) The surge bin shall be completely emptied at the end of each operating day.
7.All plants shall be equipped with a continuously operated dust collector. The collected material may be wasted or returned to the mix.
8.All plants shall be equipped with a system to meter dust returned to the mix.
9.Mineral filler bins shall be protected from moisture.
b.Dryer-Drum Plants: (1) These plants shall include cold aggregate feeders, vibratory screening units for removing oversize material from both virgin and reclaimed material, proportioning devices for controlling the quantity of each ingredient in the mixture, and any other equipment necessary to produce the mixture as specified.
2.Plants shall be equipped with a pump synchronized to the feeding mechanism so that the required percentage of PG Binder will be applied continuously and uniformly.
3.The feeding system shall be synchronized to the rest of the plant.
4.Plants shall be equipped with a system that provides a continuous electronic readout and colle ction of all setting data and made available to the Engineer.
3.Hauling Equipment: a. The truck beds shall be clea n and shall be constructed so that all materials remain in the bed while the truck is in transit.
b.All trucks shall be equipped with a suitabl e waterproof cover.
c.Any truck that causes excessive material segregation or contamination shall not be used.
4.Placement Equipment:
a.Asphaltic Concrete Mixture Laydown Machines (paver):
1.The paver shall place the full-lane width shown in the contract. The paver shall be self-propelled and able to spread and finish the material to the required thickness without material or temperature segregation of the mixtur e. The finish machines shall produce a smooth and uniform surface, a profile t hat meets the required cross section, and layers of uniform density.
2.The paver shall be equipped with a hopper to receive the asphaltic concrete. It shall be equipped with a distributing auger or other
503.03 Asphaltic Concrete
- 316 - acceptable devices that will distribute the asphaltic concrete evenly across the entire screed width.
3.The paver shall produce continuous and uniform consolidation of the asphaltic conc rete. The screed of the paver shall be adjustable to the crown and heated ac ross its entire length. The screed shall be vibratory and adjustable to meet the manufactures recommendations for the mix in use. Controls will be prov ided to prevent overheating the asphaltic material. Screed extensions shall be set to extrude the asphaltic concrete mixture at the same level as the ma in screed such that the compacted roadway or shoulder will have a uniform slope.
4.The paver shall employ an automated screed control to regulate slope and grade adjustments. A variation of 1/8 inch (3 mm) along the reference line and a mi nimum variation of 1/8 in ch (3 mm) in required transverse slope for each 12 feet (3.6 m) of lane width will be detected and compensated for by the equipment.
5.The screed shall be controlled by a self-contained grade reference system with a span length (length between extreme points of contact with the roadway) of at least 30 feet (9 m).
6.When the leading edge of the reference system encounters a localized [less than 3 feet (1 m) long] change in the roadway elevation, the sensing point shall reac t to compensate for 25% of the actual change in elevation.
7.The self-contained grade reference system shall be used at or near the centerline of the roadwa y unless this is not possible; in which case, the recommendations of the m anufacturer of the finishing machine shall be used.
8.The self-contained grade reference system shall be used to place all layers of the asphaltic c oncrete mixture, ex cept that a joint matching shoe may be used when matching the adjacent pass of the final layer and for shoulder surfacing work.
9.When required by the contract or the Engineer, such as when matching project ends, bridges, railroad crossings, and approach ends or filling settlement areas to the correc t grade, the electronic screed shall be controlled by sensors on a string line refe rence erected by the Contractor to the required elevations.
b.Side-Delivery Machines (road widener):
1.Side-delivery machines shall be self-propelled and capable of spreading and finishing the material to the required thickness with a strike-off device without segregating the mixture. The machine shall be designed for placement of asphaltic concre te in the lane adjacent to the lane in which it is operating. Side-delivery machines shall produce a smooth, uniform surface of the required cross section and density.
2.The side-delivery machine shall be equipped with a hopper to receive the asphaltic concrete before distribution to the strike-off.
3.The side-delivery machine shall be able to control the depth of placement by sens ors or other devices us ing the surface of the adjacent lane as a reference. Asphaltic Concrete 503.03 - 317 - (4) When a side-delivery machine is used, a mechanical broom shall follow the delivery machine to sweep any spilled material onto the newly placed and uncompacted surface.
5.Elevating Equipment (pickup machine):
a.Pickup machines shall transfe r, without segregating, asphaltic concrete from the roadway surfac e to the paver's receiving hopper.
b.The pickup machine shall remo ve essentially all the asphaltic concrete from the roadway surface with out inclusion of subgrade material or damage to the existing surface.
6.Material Transfer Vehicles (MTV): a. Before crossing any bridge, these vehicles must be unloaded.
7.Compaction Equipment:
a.All roller wheels shall be smooth and free from defects that would mar the surface of the work. Adju stable spring scrapers shall be fitted to each roller to scrape in both directions.
b.All rollers shall have full width wheel sprinkling devices and drip pans designed to keep contam ination off the roadway surface.
8.Curb Forming Equipment: Curb forming equipment shall extrude and compact the asphaltic concrete mixture to the required cross section.
9.Portable Scales: a. Scales shall be installed in accordance with the manufacturer's recommendations. They shall have sufficient capacity to determine the weight of a fully loaded truck.
b.The Contractor shall calibrate the scales, accurate to 0.5% of a fully loaded truck, in the Engineer's presence, or the scale shall have a current Nebraska Department of Ag riculture inspection certificate. Documentation showing that scales were calibrated by a scale company service crew during the current season is also acceptable.
c.The scale shall be cross-checked at the Engineer’s discretion for accuracy by comparing its results with a load's gross weight on an approved commercial scale.
d.If the scales are not able to weigh all axles at once, the approaches shall be extended so that the entire hauling unit will be level as each axle is measured.
e.Suitable protection shall be provided against wind currents that may affect the accuracy of the scales. The platform of the scale shall be kept clean and free from accumulations of materials.
10.Notched Wedge Equipment a. The notched wedge joint device shall be a manufactured strike-off device attached to the asphalt paver screed and able to produce the required shape and configuration a fter compaction, as detailed in the plan typicals.
503.03 Asphaltic Concrete
- 318 - b. The device shall be self-adjusting, spring-loaded, and able to generate a smooth, unifor m surface and slope without disrupting the smoothness of the paving mat.
c.The device shall be capable of applying vertical loads by pressure or ballasting methods.
d.The device may or may no t have capability of vibration.
503.04 Construction Methods
1.Preparation: a. (1) The Contractor shall prepare the roadbed, subgrade, base, and/or foundation courses as described in Division 300.
2.Before placing the asphaltic concrete, the surface of the trimmed subgrade shall be tight, dust-free, dry and rolled to firmly incorporate any loose or disturbed material and provide a suitable foundation for the subsequent construction.
b.The Contractor shall clean the pavement surface of all dirt, deleterious material, loose surfacing material, or unstable bituminous patches.
1.For all projects (including single lift projects), excessive or loose asphaltic crack filler or joint sealing material shall be removed flush with the surface.
2.For single lift projects only, all asphaltic crack filler or joint sealing material in joints or cracks 1 1/2 inches (38 mm) or more in width shall be removed to a depth of at l east 1 inch (25 mm) below the pavement surface.
c.When grade correction is necessary to meet a surface elevation, it shall be accomplished by milling or removal as shown in the contract.
d.The Contractor shall dispos e of any surfacing material along the project right-of-way left by maintenance forces.
e.(1) The Contractor shall appl y a tack coat in accordance with the requirements of Section 504 a fter the existing surface has been prepared and between each successive layer of asphaltic concrete.
2.Asphaltic concrete shall not be placed over emulsified tack coat until the emulsion has broken and all free moisture has evaporated or drained off the surface.
2.Asphalt Testing and As phalt Mix Control Strip:
a.At the Contractor’s option, the control strip may be waived. The decision to omit the control strip mu st be communicated to the Engineer prior to the start of production. When the control strip is waived:
1.The moving average of four air voids values for the first three asphaltic concrete sub lots is not valid and a pay factor of 1.0 shall be applied.
2.The first three asphaltic concrete sublots shall be subject to the following removal criteria and removal shall be at no cost to the Department. Asphaltic Concrete 503.04 - 319 - Table 503.01 Sublot Removal Criteria 1-1 Va 1-1 less than 1.5 or greater than 7.0 1-2 (Va 1-1 + Va 1-2) ÷ 2 less than 1.67 or greater than 6.67 1-3 (Va 1-1 + Va 1-2 + Va 1-3) ÷ 3 less than 1.83 or greater than 6.33 Where: Va 1-1 = the single test air voids for Sublot 1-1 Va 1-2 = the single test air voids for Sublot 1-2 Va 1-3 = the single test air voids for Sublot 1-3
b.If the control strip is not waiv ed, on the first production day, a 600 ton (544 Mg) control strip shall be placed and approved before full production begins. The Contractor sha ll construct the control strip using the approved asphalt mix design with lay down and compaction procedures that are representative for the project.
1.The Contractor shall take at least 3 control strip mixture samples and record the test results for the mixture properties. The Contractor will also record compaction density values and rolling pattern information. This data will be for in formation only and shared with the Engineer.
2.Random samples shall be taken, and the air voids shall be between the values shown in Table 503.02 Table 503.02 Control Strip Sampling Sample No. Ton (Mg) Air Voids for SPH Air Voids for SPR 1 0 to 200 (0-180) 2.5 to 6.0 1.5 to 5.0 2 201 to 400 (181-363) 2.5 to 6.0 1.5 to 5.0 3 401 to 600 (364-544) 2.5 to 6.0 1.5 to 5.0
3.Marshall or Gyratory ai r voids of each sample shall be calculated using the maximum spec ific gravity of that sample.
4.The test results must fall within the specified tolerances, but if subsequent tests c ontinue a trend toward the target values specified, the Department may tentatively accept the control strip with written assurance from the Contractor that adj ustments will be made in an effort to attain and then maintain target Specifications.
5.The control strip will be a ccepted at 100% pay if all of the following test results are met. If any of the following test results are not met, the control strip will be subject to removal.
i.The Dust to Binder ratio is between 0.70 and 1.70. (ii) CAA is no more than 5% lower than the minimum specified shown on Table 1028.02 using blended cold feed material or ignition oven test results. FAA is no more than 0.5% lower than the minimum specified using blended cold feed material or no more than 1.0% lower than the minimum specified using ignition oven test results shown on Table 1028.03. (iii) Air voids are between 2.5% to 6.0% SPH and between 1.5% to 5.0% for SPR, SLX, and SRM.
503.04 Asphaltic Concrete
- 320 - (6) Department personnel will observe testing procedures.
7.The Contractor shall rep eat the control strip process for each mix type and until an acceptab le control strip is produced.
8.When placed in areas that are to be paved, accepted control strips may remain in place and be measured as a part of the completed pavement.
9.Full production of a specific mix type may begin only after a control strip for that spec ific mix type is accepted.
10.At locations where the contract requires more than one layer (lift) of asphalt and when different mixes are used in each layer, then the control strips for the upper la yers can be placed in the lower layers.
11.Asphaltic Concrete Type SPS is excluded from any control strip requirements.
12.When a control strip is constructed, the Contractor will use the three individual air void tests within the control strip and apply those individual values to the individual air void test result of the fi rst sublot of Lot 1 to calculate the initial moving average of four and resulting pay factor for the initial sublot.
3.Placement Limitations: a. Table 503.03 shall be used w hen there is a need to restrict the routine placement of asphaltic concrete as a result of cold temperatures.
b.The Engineer may restrict t he placement of asphaltic concrete when weather conditions or other project specific conditions exist. Table 503.03 Cold Weather Asphaltic Concrete Placement Lift Thickness *Minimum Surface Temperatures Less than 2 inches (50 mm) 45°F (7C) 2 to 3 inches (50 mm to 75 mm) 37°F (3C) Greater than 3 inches (75 mm) 35°F (2C) * 32oF (0oC) for all lift thicknesses when a warm mix additive is in accordance with the contract.
c.The surface layer shall be laid in one continuous thickness over the length of the project, incl uding core out sections. Thickness adjustment in the transition sections shown in the contract shall take place in the lower layers.
d.The Contractor shall place th e asphaltic concrete mixture on a dry and frost-free surface.
e.(1) After September 15, if the haul distance exceeds 3 miles (5 km), all hauling vehicles shall be equipped with a tarp. Tarping and insulation will be required if it is determined by the Engineer that uniform temperature control of the mixt ure is not being maintained.
2.Each surface of a hauling vehicle's box shall be insulated and have an "R" value of approximately 1.0 ft2-hr-Fo/BTU[RSI 1.0m2(oC/W)]. Asphaltic Concrete 503.04 - 321 - (3) All insulating material sh all be firmly attached to the truck box, whether inside the box or out, and shall have no bulges, tears, gaps, or uneven seams.
4.Unsatisfactory or deteriorated insulating materials shall be replaced.
f.No asphaltic concrete mixture shall be placed after October 31 except as follows.
1.The Contractor may make a written request to continue asphalt placement after October 31. The request shall include the type of asphaltic concrete mixture and estimated tons to be placed. The Engineer will provide a written notice if approved. The approval will be conditional based on daily conditions. The approval may include conditions for safety, quality and traffic control.
2.The Engineer may order the contractor to continue.
4.Delivery and Production Requirements: The delivery of asphaltic concrete shall be scheduled to allow continuous lay down operations.
5.Placement Operations: a. (1) The actual mixing temperature shall be selected by the Contractor, in accordance with binder supplier recommendations, to provide adequate aggregate coating and mixt ure compaction at lay down.
2.The temperature of the asphaltic concrete mixture shall not exceed 350°F (177 C) immediately after discharge from the mixer.
3.Never shall the selection of the mixing temperature be such that drainage of the PG Binder from the aggregate will exceed contract specifications.
b.(1) Asphaltic concrete used in the construction of sections having a uniform width, and the surface layer of intersections and driveways, shall be placed with a paver.
2.The surface lift of asphaltic concrete shoulders shall be placed with a paver. Lower lifts of asphaltic concrete shoulder material may be placed with a side-delivery machine.
3.In deep, irregular, or narrow sections such as flumes, ditch lining, island noses, or where it is im practical to use a paver, the Contractor may use other appropriate methods for spreading the mixture.
4.Dumping bituminous mixtures on pavement which is not to be resurfaced will not be allowed.
c.Each asphaltic concrete layer shall meet the following thickness requirements:
1.When constructed under traffic maintained conditions, the top layer's nominal thickness sha ll not exceed 2 inches (50 mm).
2.The bottom layer's thickness shall be at least 3 inches (75 mm) when placed on a base course or the subgrade.
d.The entire width of a laye r shall be placed before any of the subsequent layer is started.
503.04 Asphaltic Concrete
- 322 - e. Under traffic maintained conditions, the Contractor shall begin each day’s placement in the lane adjac ent to the previous day’s placement when the longitudinal distance between the terminus points for the layers in the adjacent lanes is grea ter than 500 feet (150 m).
1.The Contractor has the option of constructing a notched wedge joint. If the Contractor chooses to construct this joint, it shall be built as shown in the contract. This work shall consist of constructing a notched wedge longitudinal joint between adjacent passes of asphaltic concrete lifts over 1 inch on pavement that will be op en to traffic and contains uneven lanes. The notched wedge joint shall consist of a vertical notch 1/2 the thickness of the asphalt lift, and an 8 inch to 12 inch uniform taper extending into the adjoining lane. (i). The notched wedge joint device shall be heated prior to the beginning of laydown either manu ally or as part of the notched wedge joint device. (ii). The notched wedge joint shall be constructed in one pass of the paver. A constant head of asphaltic concrete shall be supplied in front of the notched wedge to provide pre-compaction of the notched wedge joint. (iii). The taper of the notched wedge joint will be a minimum of 8” and a maximum of 12”. (iv). The notched wedge joint shall be used at any longitudinal joint locations situated between two driving lanes. The Contractor also has the option to ut ilize the notched wedge joint at other longitudinal joint locations. (v). A tack coat shall be applied to the full face of the in- place notched wedge joint, prior to the placement of full lane tack coat application.
f.Any longitudinal joint shall be parallel and coincident to the major traffic lane edges.
g.Asphaltic concrete lugs shall be constructed at all unsurfaced entrances, driveways, or intersections . They shall be 1 foot (300 mm) by 40 feet (12 m) measured along the projec t centerline. For shared entrances, the length may be increased 20 feet (6 m) for each additional entrance.
h.When surfacing extends beyond the intersection or driveway surfacing areas, the elev ation transition shall extend a minimum of 3 feet (900 mm) for each inch of elevation.
i.When the project includes surfaced intersections or driveways for which resurfacing is not shown in the contract, the roadway or shoulder resurfacing shall be feathered onto the existing intersections or driveways a minimum of 3 feet (900 mm) for each inch of elevation difference.
j.The asphaltic concrete mixt ure shall be dumped in the center of the finishing machine's hopper without overloading. Care shall be exercised to avoid spilling the mixture on the existing surfacing. The finishing machine shall be operated to produce a lane of uniform temperature, thickness and density. Asphaltic Concrete 503.04 - 323 - k. Immediately after screeding a nd before compaction is started, the surface shall be checked. Accumulations of poorly mixed asphaltic concrete which drop onto the surface shall be removed and replaced. All irregularities in alignment and grade shall be corrected.
l.The roller shall not pass ov er the unprotec ted end of the freshly placed mixture. When placemen t is discontinued, the end shall be protected by a wedge of asphaltic c oncrete, feathered 3 feet (900 mm) in length for each inch (25 mm) of layer th ickness, shall be pl aced at the end of the lane.
6.Construction of Transverse and Longitudinal Joints: a. All joints shall be well bonded. b. The Contractor shall clean and apply a tack coat to the surfaces.
c.(1) The Contractor shall cut the surface to expose material the full thickness of the layer when constructing a transverse joint at the end of the existing layer.
2.The hot mixture shall be placed in contact with the exposed surface and raked to t he proper depth and grade.
d.When constructing longitudinal joints, all voids shall be filled and the joint shall be properly "set up" to receive the maximum compression under rolling.
7.Compaction: a. The Contractor shall roll and compact the asphaltic concrete mixture while it is in a workable condition.
b.(1) Finish rolling shall be accomplished with a steel drum roller.
2.When paving adjacent to a previously placed lane or when placing the top layer of surfacing adjac ent to an existing pavement or curb, the last pass of the roller in which the fu ll roller width is entirely on the freshly placed material shall be kept appr oximately 6 inches (150 mm) from the existing facility. The final pass of the roller shall then be made over the remaining uncompacted 6 inch (150 mm) strips, tucking the material into the joint.
3.Rolling on superelevated curves shall progress from the low side in each lane, maintaining the 6 inch (150 mm) from the edge requirement of the preceding paragraph.
c.Rolling shall be continued until all roller marks are eliminated and the specified density is achieved.
d.The frequency and amplitude of vibratory rollers shall be adjusted to the manufacturer's recommendations for the thickness of layer being placed and the speed at which the roller is being operated. The Manufacturer’s recommendations shall be made available to the Engineer two weeks prior to placement.
e.The speed of the roller shall be adjusted to avoid displacement of the hot mixture. Any displacement t hat occurs shall be corrected. Rolling shall proceed continuously until all roller marks are eliminated.
503.04 Asphaltic Concrete
- 324 - f. Areas where rollers cannot be properly operated shall be compacted with appropriate equipment.
8.Preparation of Expansion Relief Joints: a. When an asphaltic concrete pavement is constructed on a Portland cement concrete pavement, the Contractor shall construct expansion relief joints as shown in the contract.
b.The Contractor shall remo ve a continuous full depth transverse section of the concrete pavement approximately 4 inches (100 mm) wide and backfill the void with asphaltic conc rete. The Contractor may use asphalt millings with the Engineer's approval.
9.No traffic shall be allowed on newly constructed pavement having a temperature of 165°F (75°C) or greater.
10.Any core hole made in the pavement by the Contractor or the Department shall be filled with asphaltic concrete and compacted to the same density as the surrounding material.
11.The Engineer may evaluate any surface irregularities caused by workmanship, such as segregation, de leterious material, tears, delamination or any other irregularities. These irregul arities shall be corrected as directed by the Engineer at no cost to the Department.
503.05 Method of Measurement
1.a. The "Asphaltic Concrete" shall be measured for payment in tons (Megagrams) on approved scales.
b.The "Asphaltic Concrete" shall be measured with automatic batching plant scales.
c.The scale tickets shall be prepared in duplicate. The Contractor shall carry the original copy of the scale ticket to the delivery point and give it to the Engineer.
d.(1) The measured quantity shall be the total weight of asphaltic concrete shown on the scale ticket without deduction for the PG Binder weight in the mixture.
2.The Engineer shall deduct the weight of all material lost, wasted, damaged, rejected, or applied contrary to these Specifications.
2.Placement of driveways and in tersections is measured in square yards (square meters). The materials used in driveways and intersections shall be included in the roadway material bid items.
3.a. PG Binder will be meas ured in tons (megagrams).
b.In the event the Contractor cannot provide evidence to verify the PG Binder quantity from the scale ti cket, the Contractor's laboratory test shall be used to determine the PG Binder percentage, unless the verification test results require the Depart ment’s test results be used.
4.Expansion relief joint preparat ion is measured by the linear foot (meter). The materials used in the expansion relief joint will be paid for in the roadway material bid items.
5.The construction of a notched wedge joint will not be measured and paid for but will be subsidiary to the associated asphaltic concrete. Asphaltic Concrete 503.06 - 325 - 6. Warm Mix Asphalt (WMA) additives are measured by the unit of each for the item “Hydrated Lime/Warm Mix Asphalt” for each ton of hot mix asphalt produced.
503.06 Basis of Payment
1.P a y I t e m P a y U n i t Asphaltic Concrete, Type ____ Ton (Tn) [Megagram (Mg)] Performance Graded Binder ____ Ton (Tn)[Megagram (Mg)] Placement of Asphaltic Concrete Square Yard (SY) for Intersections and Driveways [Square Meter (m 2)] Prepare Expansion Relief Joint Linear Foot (LF) [Meter (m)] Hydrated Lime/Warm Mix Asphalt Each (ea) 2. For each sublot of Asphaltic Concrete Type SPS, SPR, SPH, SLX, and SRM, the asphaltic concrete shal l be paid for each ton of “Asphaltic Concrete Type _____” placed and accepted. The incentive/disincentive shall be calculated on a lump sum basis based on the unit price, tonnage and quality pay factors. This will be a product of all applicable pay factors, including density and smoothness. This factor will be calculated on Department software and will provide for a weighted pay factor for each type of Asphaltic Concrete on the project, and then summed up and paid for as a single incentive/disincentive as a lump su m. The tonnage that is applicable toward this incentive/disincentive shall only be tonnage that is paid for by ‘mainline roadway and shoulder tonnage items’ and for the full thickness and tonnage paid for and accepted. No incentive will be paid for project patching or tonnage used for maintenance patchin g. When a control strip is not constructed, the pay factor for the runn ing average of four air voids shall be fixed at 1.0 for the first thr ee asphaltic concrete sublots.
3.The final pay factor for total project tonnage for any one type of superpave asphaltic concrete, expr essed as a percentage, shall be computed as follows: P1(T1) + P2(T2) + P3(T3)… T1 + T2 + T3… Where P1, P2, P3 = percent pay factor for each sublot T1, T2, T3 = tons (Mg) at respective pay factor
4.a. If the temperat ure exceeds 350°F (177 C) but does not exceed 400°F (204 C) immediately after discharge from the mixer, the pay factor shall be 0.90.
b.If the temperature of the mixture exceeds 400°F (204 C), the material will be rejected or, if used on the project, the pay factor for the material will be 0.40.
5.PG Binder and Rejected Material a. Pay Factor for PG Binder is determined by the specifications in Section 1029.
b.When asphaltic concrete in any lot or portion of a lot is rejected and removed from the road, payment will not be made for the asphaltic concrete or for the PG Binder contained in the rejected material. The determination of the quantit y of PG Binder for which payment will not be
503.06 Asphaltic Concrete
- 326 - made will be based on the percent of virgin PG Binder used in the rejected material.
1.The order of precedence to determine the PG Binder quantity is:
i.Actual lot tests. (ii) The average of the day’s run. (iii) The job-mix formula. c. The test data from the ac tual “rejected” lot of asphaltic concrete will be used to determine the quantity of virgin PG Binder that is rejected.
6.Pay factors for asphaltic concre te mixtures do not alter the price paid for PG Binder.
7.Tack coat will be paid for in accordance with Section 504. 8. Disposal of the surfacing material discarded by maintenance forces will be measured in accordance with the requirements of Subsection 919.04 and paid for in accordance with Subsection 919.05.
9.a. Any asphaltic concrete found contaminated by petroleum distillates, hydraulic fluid, or other asphalt solvents may be rejected. If already incorporated in the work, it shall be removed and replaced at no additional cost to the Department or, at the Engineer's option, may be left in place and paid for at 40% of the bitu minous mixture's contract unit price.
b.The quantity of asphaltic concrete to be removed or paid for at the reduced price will be based on full lane widths extending beyond the limits of the contaminated area 25 feet (7.6 m) in both directions.
10.If more than one type of asphaltic concrete is required, the pay item will be subdivided so the quantities of each type are documented.
11.The coring, filling, and testing of density cores are subsidiary to “Asphaltic Concrete, Type ____”.
12.Payment is full compensation for all work described in this Section. - 327 - SECTION 504 -- TACK COAT
504.01 Description
1.Tack coat is the application of asphaltic materials to bases or surfacing. The tack coat shall be appl ied to surfaces on which bituminous materials will be placed. When spec ified, tack coat will be applied on other surfaces.
504.02 Material Requirements
1.The type and grade of emulsified asphalt shall be specified in the contract and shall conform to the requ irements in Sections 1031 or 1032. Fast-Set type emulsified asphalt shal l meet the requirements of Table 504.01. Table 504.01 CFS-1, FS-1 Emulsified Asphalt Requirements Tests on emulsion: Specification Viscosity, Saybolt Furol, T 59, 25oC (77oF), sec. 20 – 100 Sieve Test, Percent Retained, maximum (note 1) 0.10 Residue by Distillation, Percent, minimum 57.0 Storage Stability, Percen t, maximum (note 1) 1.0 Tests on distillation residue: Penetration, dmm. 40 - 175 Ductility, 25oC (77oF), cm., minimum 40 Solubility in Trichloroethylene, Percent, minimum 97.5 Note 1: See note “b” of AASHTO M 208 - 2015 Shall be formulated as either a cationic or anionic, fast-setting emulsion that is suitable for tack coat diluti on, and to have an accelerated breaking time in cooler temperature applications.
504.03 Construction Methods
1.Before the application of tack coat, the surface shall be cleaned as described in Section 501.
2.The Contractor shall furnish and apply the tack coat.
3.a. A pressure distributor shal l be used for the application of the tack coat. Uniform application is required. Hand sprayers may be used in applying tack coat to small or irregular sections.
b.Emulsified asphalt shall be diluted with potable water at a rate of one part water to one part emulsified asphalt by either the Supplier or the Contractor.
c.The rate of application shall be adequate to bond the new bituminous layer to the existing surface. This shall be from 0.10 to 0.20 Gal/SY (0.45 to 0.90 L/m2) when applied to existing or milled surfaces and from 0.05 to 0.10 Gal/SY (0.23 to 0.45 L/m2) when applied to the freshly laid asphaltic concrete.
4.The Contractor shall furnish and apply a tack coat as directed by the Engineer to seal surfaces and pr event infiltration of moisture when construction will be interrupted by weathe r or the project is shut down for the winter.
Source: Nebraska Standard Specifications for Highway Construction, 2017 Edition. Pages 348–360 of 1,048.