SECTION 412 — RUBBERIZED ASPHALT CHIP SEALING 400-39 — RUBBERIZED ASPHALT CHIP SEALING
412.01 Description.
This specification covers all materials, equipment, construction, application, and post-placement procedures for the rubberized asphalt chip sealing of existing paved surfaces at the required locations. The work consist s of an application of rubberized asphalt binder followed by an application of pre-coated cover aggregate.
412.02 Materials.
Asphalt Cement. Use n eat asphalt cement that meets AASHTO M320 for PG 58- 28. Ensure that t he high temperature grade does not exceed PG 58. Granulated Rubber. Use granulated rubber that is vulcanized rubber from the ambient temperature processing of scrap pneumatic tires. Use granulated rubber that meets the following gradations; no substitutions will be accepted: Sieve Size Percent Passing #10 100 #16 90 – 100 #30 25 – 100 #80 0 – 20 The use of rubber of multiple types from multiple sources is acceptable if the overall blend of rubber meets the gradation requirements. Ensure that the length of the individual rubber does not exceed ⅛ in. Ensure that t he specific gravity of reclaimed vulcanized ground rubber is between 1.10 and 1.20. The rubber supplier shall supply the c ertification. Use rubber in the rubberized asphalt binder that is free of loose fabric, wire, and other contaminants. Up to 4 percent (by weight of rubber) calcium carbonate or talc may be added to prevent caking or sticking of the particles together. Ensure that the ground rubber is sufficiently dry to be free flowing and not produce foaming when blended with the hot PG binder. Cover Aggregate. Use cover aggregate that is virgin crushed quarry rock from a RIDOT approved source. Do not use processed gravel. For the material retained on the #4 sieve, ensure that not more than 10 percent of the particles have a flatness or elongation ratio greater than 3:1 (ASTM D4791). Ensure that t he aggregate wear, from resistance to abrasion, is a maximum of 30 percent as determined by the Los Angeles Abrasion test (AASHTO T96). Pre-heat t he aggregate to a temperature between 280°F and 320°F, and uniformly and completely precoat with a PG 64 -28 or PG 58-28 before application. Determine the asphalt content for the precoating by laboratory and field testing that is approved by the Engineer. Ensure that the gradation meets the following limits.
Part 400 — Asphalt Pavements August 2025
400-40 SECTION 412 — RUBBERIZED ASPHALT CHIP SEALING Sieve Size Percent Passing ½ in. 100 ⅜ in. 85 – 100 #4 0 – 8 #8 0 – 4 #200 0 – 2 Note: Determine a suitable location for stockpiling the required aggregate and ensuring that stockpiles do not become contaminated. Clean up at the stockpile sites and at all roads between the stockpile and the Project location. A minimum of 30 days before construction, provide a representative sample of the proposed aggregate to the asphalt rubber supplier for testing. Perform gradation testing to determine the design application rates for the asphalt rubber binder and the cover aggregate. Perform a coating and stripping test (AASHTO T 182) to ensure compatibility of the asphalt rubber binder with the processed aggregate. Provide a copy of the test results to the Engineer before the start of work. Rubberized Asphalt. Add granulated rubber to the PG58-28 asphalt cement at a rate of 18 percent ±3 percent by total weight (i.e., asphalt cement plus granulated rubber). Ensure that the physical requirements of the rubberized asphalt meet ASTM D 6114 Type II. The supplier of the rubberized asphalt shall certify the percent of granulated rubber in the blend. Ensure that the temperature of the asphalt cement is between 325°F and 400°F at the time the granulated rubber is added. Combine and mix together the asphalt cement and granulated rubber in a blender unit and react for a minimum of one hour. Ensure that there are no agglomerations of rubber particles in excess of 2 in. in the least dimension in the mixing chamber. Maintain the temperature of the asphalt-rubber binder immediately after mixing between 325°F and 375°F for a minimum of 45 minutes before use. When a job delay occurs after full reaction, the rubberized asphalt may be allowed to cool. Reheat the rubberized asphalt slowly just before application but not to a temperature exceeding 375ºF. An additional quantity of granulated rubber or additive not exceeding 3 percent by volume of the rubberized asphalt may be added after reheating. Testing and Certification. Sample the rubberized asphalt once per lot at the point of manufacture, tested and certified by an AASHTO resource (formally AMRL) accredited laboratory approved for asphalt rubber binder testing. The laboratory shall certify that the rubberized asphalt meets the requirements of ASTM D 6114 Type II specifications. A lot is defined as each batch produced but not to exceed the volume of the manufacturer’s dedicated asphalt rubber reaction/storage tank. In addition to the ASTM D 6114 Type II specification, to ensure adequate blending residence time and binder quality, test every lot as follows:
Part 400 — Asphalt Pavements August 2025
SECTION 412 — RUBBERIZED ASPHALT CHIP SEALING 400-41 Test (on the produced asphalt rubber binder) Result AASHTO T315 Original Binder 2mm DSR @ 82 G*/sin (d) >1.00 kPA Report all data to the Engineer. Reporting. Before starting work, submit a Quality Control Plan from the a sphalt rubber supplier that meets the format requirements of AASHTO R 26. Submit a weekly manufacturer’s report for each lot of asphalt rubber produced that includes the following as a minimum: • Total quantity of asphalt binder in tons • Tons and percentage of ground rubber based on total asphalt rubber binder • ASTM D6114 certified test results • AASHTO T 315 Original Binder 2mm DSR @ 82 Engineering. Determine the asphalt content and mixing time of the pre- coated aggregate to obtain a uniform and complete pre-coating. Forward samples to the Engineer for approval. Design the rubberized asphalt chip seal surface treatment. No later than two weeks before work commences, submit for the approval of the Engineer the surface treatment design with supporting test data, specifying the additives for the rubberized asphalt, application rate of the rubberized asphalt, and the source, composition, and application rate of the cover aggregate. Include samples of each material with the submittal. Once the materials and design are approved, no substitution will be permitted unless approved by the Engineer.
412.03 Construction Methods.
Equipment.
a.Mechanical Blender. Ensure that t he method and equipment for combining the ground rubber and PG asphalt binder is designed to be accessible so that the Engineer can readily determine the percentage of each material being incorporated into the mixture. Use equipment in the production and proportioning of asphalt-rubber binder that includes the following as a minimum: ● An asphalt heating tank or heat exchanger with hot oil heat transfer to heat the PG asphalt binder to the necessary temperature before blending with the ground rubber. Equip the unit with a thermostatic heat control device. ● A mechanical blender for proper proportioning and thorough mixing of the PG asphalt binder and ground rubber. Ensure that the unit has a Coriolis type mass flow meter capable of measuring and recording the total quantity of asphalt binder in tons. Determine the quantity of ground rubber by weight using either a hopper equipped with load cells or a feeder equipped with a belt scale. Record the total weight in tons and
Part 400 — Asphalt Pavements August 2025
400-42 SECTION 412 — RUBBERIZED ASPHALT CHIP SEALING percentage of ground rubber based on total asphalt rubber binder. Report all data to the awarding authority as outlined in Subsection 412.02.6. ● A dedicated asphalt rubber reaction/storage tank equipped with a heating system to maintain the proper temperature of the binder and an internal mixing unit capable of maintaining a homogeneous mixture of asphalt and ground rubber.
b.Distributor Truck. On Projects exceeding 35 tons of rubberized asphalt, ensure that at least two pressure-type asphalt distributor trucks in good condition are available. Equip the distributor with an internal heating device capable of heating the material evenly up to 425ºF, an internal agitation unit capable of maintaining a proper mix of asphalt cement and granulated rubber, an adequate pump capacity to maintain a high rate of circulation in the tank and to spray the rubberized asphalt at a viscosity of 1500 to 5000 centipoise, and adequate pressure devices and suitable manifolds to provide constant positive cut-off to prevent dripping from the nozzles. Equip the distributor with an electronically controlled computerized compensation unit for controlling application rates at various width and speed changes. Ensure that t he application unit has electronic controls and a digital read-out installed and is operated from the inside of the cab of the distributor. Ensure that the distributor bar is fully circulating. Repair or remove any distributor that produces a streaked or irregular distribution of the material. Use distributor equipment that includes a tachometer, pressure gauges, volume measuring devices, and thermometer for reading the temperature of the tank contents. Locate the c ontrols for the width and rate of spray from the spray bar in the cab of the truck, and ensure that the controls enable a uniform application at the specified rate per square yard within a tolerance of 0.05 gal/sq yd. Equip the distributor with a continuous mechanical means to ensure that all nozzles are clean at all times. If a continuous mechanical means is not present, use a bootman to accompany the distributor who rides in a position so that all spray bar nozzles are in full view and readily accessible for unplugging.
c.Hauling Equipment. Equip tank trucks used for the transportation of asphalt rubber with a heating system to maintain the proper temperature of the binder and an internal mixing/agitation unit capable of maintaining a homogeneous mixture of asphalt and ground tire rubber while in transit. Use trucks for hauling cover aggregate that are rear discharge conveyor-fed or live bottom trucks that are equipped with a device to lock onto the hitch at the rear of the aggregate spreader to prevent spillage. Ensure that sufficient hauling vehicles are available to ensure continuous operation of the distributor and aggregate spreader.
d.Aggregate Spreader. Use an aggregate spreader that is hydrostatically driven and self- propelled. Use a spreader that is equipped with a hydraulically controlled variable adjustable head that can spread cover aggregate in widths from 4.5 ft to 18 ft. Mount the spreader on pneumatic tires, and apply the cover aggregate on the road surface and
Part 400 — Asphalt Pavements August 2025
SECTION 412 — RUBBERIZED ASPHALT CHIP SEALING 400-43 ensure that the tires do not contact the road surface until after the cover aggregate has been applied. Equip the unit with an electronic radar type sensor to measure ground speed and that will automatically adjust the cover aggregate application rate depending on the width of application and the speed of the spreader. Ensure that the sensor can apply cover aggregate at a uniform coverage on any grade from 0 to 6 percent. Equip the spreader with an integral hopper with a minimum capacity of 5 tons of cover aggregate that can be filled by trucks to ensure that the truck tires never contact the rubberized asphalt treated road surfaces until the cover aggregate has been properly applied. To maintain constant cover aggregate application, use a self-locking truck hitch that permits towing of aggregate trucks without stopping the spreader and that can maintain positive engagement over irregular terrain.
e.Pneumatic Tire Rollers. Use a minimum of three self-propelled, multiple wheel pneumatic tire rollers. Ensure that each weighs a minimum of 10 tons, has a total compacting width of at least 56 in., and has a minimum tire pressure of 100 psi.
f.S elf -Propelled Rotary Sweepers . Use a minimum of two self -propelled rotary pick -up sweepers that are designed, maintained, equipped, and operated so that the pavement surface can be swept clean. Equip the rotary sweepers with adjustable down pressure on the sweeper heads and that can temporarily store the picked up material from the surface of the pavement for disposal offsite.
g.P ilot Ca r. Provide a car that can guide traffic during chip seal work operations. Ensure that the vehicle meets the requirements of the latest edition of the MUTCD. Weather Limitations. Do not apply the rubberized asphalt when weather conditions are unfavorable to obtaining a uniform spread. Only proceed with construction when the pavement surface temperature is at least 50°F and rising. Ensure that no water or moisture is present on the road surface. Road Surface Preparation. Sweep and clean the area to be sealed of vegetation, debris, loose aggregate, and soil, particularly soil that is bound to the surface. Complete the work to remove pavement markings and seal cracks before the application of asphalt rubber binder and cover aggregate. Raise to grade all localized depressions, trench cuts, utility settlements, and joint settlements with Class
4.75 HMA shim course produced according to SECTION 401. Apply a tack coat to the surface
before the shim course is placed. Mill high spots, localized bumps, and joints to raise the surface to grade or by using other treatments as approved by the Engineer. At the limits of the work, ensure that there is a smooth transition of the profile between the existing pavement and the rubberized asphalt chip seal. Remove and properly dispose of all pavement markings, with the exception of temporary markings (waterborne paint) . Use fast drying waterborne pavement markings to replace the removed existing pavement markings. Protect manholes, valve boxes, and other service entrances from the applied material. Cover and seal bridge joints, appurtenances, drainage openings, etc. , to prevent clogging and prevent the entry of loose aggregate. Do not begin application of the rubberized asphalt chip seal until the surface preparation has been approved by the Engineer.
Part 400 — Asphalt Pavements August 2025
400-44 SECTION 412 — RUBBERIZED ASPHALT CHIP SEALING Construction Procedures.
a.Rubberized Asphalt Application. Apply t he rubberized asphalt uniformly at double coverage at a temperature of between 340°F to 400°F at the approved design application rate between 0.55 to 0.65 gal/sq yd. The actual rate of application within these ranges requires that the cover aggregate be embedded at 50 percent of the stone particle size into the asphalt rubber binder with minimal stone loss following compaction. Ensure that longitudinal joints are reasonably true to line and parallel to centerline. Where any construction joint occurs, broom and blend the edges back so that there are no gaps, the elevations are the same, and the joints are free from ridges and depressions. Overlap longitudinal joints from 4 in. to 6 in. During application, prevent the adjacent pavements, curbing, structures, vehicles, foliage, and personal property from any marring or discoloration. Limit each spray application to 3000 ft in length. Place, roll, and sweep cover stone. Then, drop back and square off the 3000-ft chip seal placement before proceeding.
b.Cover Aggregate Application. Ensure that the application of cover aggregate follow s as close as possible behind the application of the rubberized asphalt. Ensure that the asphalt is not applied any further in advance of the aggregate spreader than can be immediately covered. Do not allow construction equipment or other vehicles to drive on the uncovered rubberized asphalt. Spread the hot-precoated cover aggregate uniformly and completely across the hot rubberized asphalt by a self -propelled spreader at the approved design application rate within a tolerance of +5 lb/sq yd . Ensure that the application rate is not less than 30 lb/sq yd. Cover any deficient areas with additional cover material to provide total coverage.
c.Ro lling . Initiate rolling with pneumatic tire rollers immediately following the spread of pre- coated aggregate. Ensure that there are at least three passes of a roller to embed the cover aggregate particles firmly into the rubberized asphalt. To attain c overage, use as many passes as necessary to cover the entire width being spread. A pass is defined as one movement of a roller in either direction. Ensure that the roller speed does not exceed 6 mph. Do not allow any steel wheel rollers.
d.I nitial Sweeping. When the maximum amount of aggregate has been embedded into the asphalt rubber binder and the pavement has cooled, sweep or otherwise remove all loose material. Perform the removal to avoid the displacement of any embedded aggregate or any damage to the new surface. Remove all loose cover material from the paved surface by sweeping when the chip sealed surface has cooled to below 120°F after application; however, if the Engineer determines that conditions are not conducive to obtaining the best results due to weather, temperature, or other reasons, discontinue sweeping until the Engineer has determined the best time for removal. Collect the sweeping accumulations and dispose of properly off site.
e.S ite Clean Up . Uncover and unseal all drainage openings and clean any covers or grates that the cover aggregate and rubberized asphalt may have adhered to and remove any excess material in areas such as driveways, gutters, and intersections as specified by the
Part 400 — Asphalt Pavements August 2025
SECTION 412 — RUBBERIZED ASPHALT CHIP SEALING 400-45 Engineer. On a daily basis, remove any debris associated with the performance of the work.
f.Protection of Surface. Do not allow traffic on the chip sealed road surface until all rolling has been completed and the asphalt rubber binder has cooled and set as satisfactory to the Engineer. Ensure that traffic does not exceed 25 mph by the use of a pilot car. Use the pilot car to control traffic flow at all points during chip seal work operations. Post “Loose Stone” signs at the beginning limit of the chip seal operation and at every one-mile interval. Ensure that the speed limit and other required signing meets all Department and Contract requirements. Ensure that the signs remain in place for a minimum of 24 hours after the chip seal has been placed. Do not remove signing until the loose aggregate is removed from the roadway and all other Contract requirements are fulfilled ( e.g., line striping) so that the original posted speed limit can be reinstated. The Contractor shall be responsible for any damage done to vehicles as a result of the operation.
g.P ost Placement Sweepings . Conduct post placement sweepings at the following times: ● Five to seven days after the rubberized asphalt chip sealing operation, and ● Between October 15 and November 15 after the rubberized chip sealing operation For each sweeping, remove all loose cover aggregate from the pavement surface, including the shoulders. Collect and properly dispose of the accumulations of sweepings off site.
412.04 Method of Measurement.
Rubberized Asphalt Chip Sealing will be measured by the number of square yards of rubberized asphalt chip seal placed. Removal of pavement markings will be measured by the LF.
412.05 Basis of Payment.
The Department will pay for the completed and accepted quantities at the Contract unit price as follows. Pay Item Pay Unit Rubberized Asphalt Chip Sealing SY The price constitutes full compensation for traffic control and pilot car; mobile cell phones; surface preparation; furnishing, transporting, handling, placing, and rolling the material specified; all sweeping and removal of excess aggregate; site cleanup; and furnishing all labor, tools, equipment, and incidentals required to finish the work, complete and accepted. The shim course will be paid for under separate items in the C ontract. The cost of tack coat for shim course is incidental and not paid separately. Removal of pavement markings is paid under Subsection T20.05.
Part 400 — Asphalt Pavements August 2025
400-46 SECTION 412 — RUBBERIZED ASPHALT CHIP SEALING Include the cost for the temporary waterborne pavement markings to replace the removed pavement markings in the unit bid price for “Remove Existing Pavement Marking Lines.”
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Source: Standard Specifications for Road and Bridge Construction (Blue Book), 2022 (Aug 2025 compilation) Edition. Pages 258–265 of 951. View official source ↗