SECTION 309 - FOAMED ASPHALT 3-21 FULL DEPTH RECYCLED PAVEMENT (With Foamed Asphalt)
309.01 Description This work shall consist of pulverizing a portion of the existing
roadway structure into a homogenous mass, treating the pulverized material with the foamed asphalt process, and placing and compacting this material to the lines, grades, and dimensions shown on the plans or established by the Resident. MATERIALS 309.020 Pulverized Material Pulverized material shall consist of the existing asphalt pavement and one inch or more as specified of the underlying gravel, pulverized and blended into a homogenous mass. Pulverized material will be processed to 100 percent passing a 2 in square mesh sieve. 309.021 New Aggregate and Additional Recycled Material New aggregate, if required by the contract, shall meet the requirements of Section 703.10 - Aggregate for Untreated Surface Course and Leveling Course, Type A. Aggregate Subbase Course Gravel Type D processed to 100 percent passing a 2 inch square mesh sieve and meeting the requirements of 703.06 – Aggregate for Base and Subbase may be used in areas requiring depths greater than 2 inches. New aggregate required to restore grade and/or cross-slope shall be measured and paid for under the appropriate item. Crusher dust required as part of the job mix shall be considered part of the 309 item and will not be measured for payment. Recycled material, if required, shall consist of salvaged asphalt material from the project or from off-site stockpiles that has been processed, prior to use to 100 percent passing a 2 in square mesh sieve. Recycled material shall be conditionally accepted at the source by the Resident. It shall be free of winter sand, granular fill, construction debris, and other materials not generally considered asphalt pavement. Recycled material generated and salvaged from the project shall be used within the roadway limits to the extent it is available as described in 309.06. No additional payment will be made for material salvaged from the project. Recycled material supplied from off-site stockpiles shall be paid for as described in the contract, or by contract modification. 309.022 Asphalt Binder The asphalt binder used in the foamed asphalt process shall be Performance Grade 64-28 or 58-28 meeting the requirements of AASHTO M320. 309.023 Portland Cement The Portland Cement shall be Type I or II meeting the requirements of AASHTO M85. 309.024 Hydrated Lime Hydrated Lime shall meet the requirements of AASHTO M216. 3-22 309.025 Crusher Dust Crusher dust, if required by the mix design, shall be free from friable or deleterious material, including excessive mica, and shall meet the following gradation requirements: Sieve Size Percent Passing 12.5 mm [½ in] 100 0.075 mm [No. 200] 10 - 20 309.026 Water Water shall be clean and free from deleterious concentrations of acids, alkalis, salts or other organic or chemical substances. EQUIPMENT 309.030 Pulverizer The modified milling or recycling machine shall, as a minimum, have the following features: EHT***
a.A minimum power capability of 600 horsepower.
b.Two microprocessor-controlled systems, complete with 2 indep endent pumping systems and spray bars, to regulate the application of foamed asphalt stabilizing agent, separate from water (for increasing the moisture content of the recycled material), in relation to the forward speed and mass of the material being recycled.
c.Two spray bars shall each be fitted with self-cleaning nozzl es at a maximum spacing of one nozzle for each 6 in width of the chamber.
d.The foamed asphalt shall be produced at the spraybar in indi vidual expansion chambers into which both hot asphalt and water are injected under pressure through individual and separate small orifices that promote atomization. The rate of addition of water into hot asphalt shall be kept at a constant (percentage by mass of asphalt) by the same microprocessor.
e.An inspection (or test) nozzle shall be fitted at one end of the spraybar that produces a representative sample of foamed asphalt.
f.An electrical heating system capable of maintaining the temp erature of all asphalt flow components above 300°F.
g.A single asphalt feed pipe installed between the modified mi lling or recycling machine and the supply tanker. Circulating systems that incorporate a return pipe to the supply tanker shall not be used.
h.The recycler shall be fitted with a front breaker bar system to ensure that the reclaimed material is broken down to the sizing outlined in 309.020. 309.031 Liquid Mixer Unit or Distributor Only tankers with a capacity exceeding 2500 gal shall be used to supply the recycling machine with asphalt. Each tanker shall be fitted with two recessed pin-type tow hitches, one in front and the other behind, thereby allowing the tanker to be pushed from behind by the recycling machine, and to push a water tanker in front. No leaking tanker will be permitted on the job site. In addition, each tanker shall be equipped with the following: 3-23
a.A thermometer to show the temperature of the contents in the bottom third of the tank.
b.A rear feed valve, with a minimum internal diameter of 3 in, capable of draining the contents of the tank when fully opened.
c.Insulation to retain heat.
d.A calibrated dipstick marked at intervals of no more than 25 gal, for measuring the contents of the tank. 309.032 Cement or Lime Spreader Spreading of the Portla nd Cement or Hydrated Lime shall be done with a spreader truck designed to spread dry particulate (such as Portland Cement or Lime) or other approved means to insure a uniform distribution across the roadway and minimize fugitive dust. Pneumatic application, including through a slotted pipe, will not be permitted. Other systems that have been developed include fog systems, vacuum systems, etc. Slurry applications may also be accepted. The Department reserves the right to accept or reject the method of spreading cement. The Contractor shall provide a method for verifying that the correct amount of cement is being applied. 309.033 Placement Equipment Placement of the full depth recycled material to the required slope and grade shall be done with an approved highway grader or by another method approved by the Resident. 309.034 Rollers The full depth recycled material shall be rolled with a vibratory pad foot roller, a vibratory steel drum soil compactor and a pneumatic tire roller. The pad foot roller drum shall have a minimum of 112 tamping feet 3 inches in height, a minimum contact area per foot of 17 in2, and a minimum width of 84 inches. The vibratory steel drum roller shall have a minimum 84 inches width single drum. The pneumatic tire roller shall meet the requirements of Section 401.10 and the minimum allowable tire pressure shall be 85 psi. MIX DESIGN The Department will supply a mix design for the foamed asphalt based on test results from pavement and soil analysis taken to the design depth. The Department will provide the following information prior to construction:
1.Percent of asphalt to be used.
2.Percent of water to be used in the foaming process.
3.Quantity (if any) of crusher dust to be used.
4.Quantity of lime or cement to be added.
5.Optimum moisture content for proper compaction and dispersion of foamed asphalt.
6.Additional aggregate (if required). 3-24 After a test strip has been completed or as the work progresses, it may be necessary for the Resident to make necessary adjustments to the mix design. Changes to compensation will be in accordance with the Mix Design Special Provision. CONSTRUCTION REQUIREMENTS
309.04 Pulverizing The entire depth of existing pavement shall be pulverized
together with approximately 1 inch or more of the underlying gravel into a homogenous mass. All pulverizing shall be done with equipment that will provide a homogenous mass of pulverized material, processed in-place, which will pass a 2 in square mesh sieve.
309.05 Weather Limitations When foamed asphalt is used, full depth recycled work
shall be performed when; a Foaming operations will be allowed between May 15 th and September 15th inclusive in Zone 1 - Areas north of US Route 2 from Gilead to Bangor and north of Route 9 from Bangor to Calais. Foaming operations will be allowed between May 1st and September 30th inclusive in Zone 2 - Areas south of Zone 1 including the US Route 2 and Route 9 boundaries. b The atmospheric temperature, as determined by an approved the rmometer placed in the shade at the recycling location, is 50°F and rising. c When there is no standing water on the surface. d During generally dry conditions, or when weather conditions a re such that proper pulverizing, adding, mixing, and curing can be obtained using proper procedures, and when compaction can be accomplished as determined by the Resident. e When the surface is not frozen and when overnight temperature s are expected to be above 32°F. f Wind conditions as such that the spreading of lime or cement on the roadway ahead of the recycling machine will not adversely affect the operation.
309.06 Full Depth Recycling Procedure New aggregate or recycled material meeting
the requirements of Section 309.021 - New Aggregate, and Recycled Material shall be added as necessary to restore cross-slope and/or grade before initial pulverizing. Locations will be shown on the plans or described in the construction notes; the Resident may add other locations while construction of the project is in progress. The Contractor will use recycled material to the extent it is available, in lieu of new aggregate. The material shall then be pulverized, processed, and blended into a homogeneous mass passing a 2 in square mesh sieve. Material found not pulverized down to a 2 in size will be required to be reprocessed by the recycler with successive passes until approved by the Resident. Should the Contractor be required to add new aggregate or recycled material to restore cross-slope and/or grade after the initial pulverizing process, those areas will require re- processing to blend into a homogenous mass passing a 2 in square mesh sieve. The resultant material from the initial pulverizing processes shall be graded and compacted to the cross-slope and profile shown on the plans or as directed by the Resident. The Contractor will also be responsible for re-establishing the existing profile grade. The 3-25 completed surface of the full depth recycled course shall be shaped and maintained to a tolerance, above or below the required cross sectional shape, of ⅜ inch. The initial pulverizing process density requirements will be the same as Section 309.08 unless otherwise directed by the Resident. Following completion of the initial pulverizing and blending process the dry stabilizing agents (lime or cement) shall be spread uniformly over the full width of roadway to be recycled prior to each pass of the foaming operation, and in a continuous process by means of a mechanical spreader. Dry stabilizing agents shall be spread at the prescribed rate of application provided by the Department. If required by the mix design, a uniform layer of crusher dust or other aggregate specified shall be spread over the full width of the roadway just prior to the foaming procedure. Foamed asphalt shall be incorporated into the material to a depth determined by the pavement design. These additives shall then be uniformly blended into a homogeneous mass until an apparent uniform distribution has occurred. The Resident may adjust the rate of application as necessary. Asphalt binder shall be added to the milling or recycling process by pumping from a mobile bulk tanker that is pushed from behind by the recycling machine. Tankers shall be equipped with a built-in thermometer to ensure that the bituminous stabilizing agent is maintained at 375F + 10F. The system employed to add the foamed asphalt to the recycling process shall conform to the equipment requirements specified in this Section. Sufficient water shall be added through the recycler head during the recycling process to ensure thorough blending to meet the optimum moisture for compaction as specified. Water shall be added only by means of a controlled system on the recycling machine. Care shall be taken to prevent excessive wetting. A second water truck may be required during recycling operations to assist in the compaction and water control efforts. The rate of water supplied shall be kept constant unless changed due to project material changes. The resultant material shall be graded and compacted to the cross-slope and profile shown on the plans or as directed by the Resident. The Contractor will also be responsible for re-establishing the existing profile grade. The completed surface of the full depth recycled course shall be shaped and maintained to a tolerance, above or below the required cross sectional shape, of ⅜ in. Areas not meeting this tolerance will be repaired as described in Section 309.061. After compaction, the roadway surface shall be treated with a light application of water, and rolled with pneumatic-tired rollers to create a close-knit texture. The finished layer shall be free from:
a.Surface laminations.
b.Segregation of fine and coarse aggregate.
c.Corrugations, centerline differential, potholes, or an y other defects that may adversely affect the performance of the layer. 3-26 The Contractor shall protect and maintain the recycled layer until a lift of pavement is applied. Frequent light watering shall be performed to prevent the surface from drying out. Any damage or defects in the layer shall be repaired immediately. An even and uniform surface shall be maintained. The recycled surface shall be swept prior to hot mix asphalt placement. 309.061 Repairs Repairs and maintenance of the recycled layers, during and after the curing period, resulting from damage caused by traffic, weather or environmental conditions, or resulting from damage caused by the Contractor’s operations or equipment, shall be completed at no additional cost to the Department. Low areas will be repaired using a hot mix asphalt shim. Areas up to 1 in high can be repaired by either milling the high area or shimming the low areas adjacent to the high area with hot mix asphalt. Areas greater than 1 in high will be repaired by shimming the low areas adjacent to the high area with hot mix asphalt. All repair work will be done with the Resident’s approval at the Contractor’s expense. TESTING REQUIREMENTS
309.07 Quality Control The Contractor shall operate in accordance with the
approved Quality Control Plan (QCP) to assure a product meeting the contract requirements. The QCP shall meet the requirements of Section 106.4 - Quality Control and this Section. The Contractor shall not begin recycling operations until the Department approves the QCP in writing. Prior to performing any recycling process, the Department and the Contractor shall hold a Pre-recycle conference to discuss the recycling schedule, type and amount of equipment to be used, sequence of operations, and traffic control. A copy of the QC random numbers to be used on the project shall be provided to the Resident. All field and plant supervisors including the responsible onsite recycling process supervisor shall attend this meeting. The QCP shall address any items that affect the quality of the Recycling Process including, but not limited to, the following:
a.Sources for all materials, including New Aggregate and Addit ional Recycled Material.
b.Make and type of rollers including weight, weight per inch o f steel wheels, and average contact pressure for pneumatic tired rollers.
c.Testing Plan.
d.Recycling operations including recycling speed, yield monito ring, procedures for avoiding recycling and curing in inclement weather, methods to ensure that segregation is minimized, procedures for mix design modification, grading and compacting operations, and cement and lime application procedure.
e.Methods for protecting the finished product from damage and procedures for any necessary corrective action.
f.Method of grade checks.
g.Examples of Quality Control forms. 3-27
h.Name, responsibilities, and qualifications of the Responsibl e onsite Recycling Supervisor experienced and knowledgeable with the process.
i.A note that all testing will be done in accordance with AASH TO and MaineDOT/ACM procedures. The Project Superintendent shall be named in the QCP, and the responsibilities for successful implementation of the QCP shall be outlined. The Contractor shall sample, test, and evaluate the full depth reclamation process in accordance with the following minimum frequencies: MINIMUM QUALITY CONTROL FREQUENCIES Test or Action Frequency Test Method Density 1 per 1000 ft / lane AASHTO T 310 Air Temperature 4 per day at even intervals Surface Temperature At the beginning and end of each days operation Yield of all materials (The daily yield, yield since last test, and total project yield.) 1 per 1000 ft / lane The Department may view any QC test and request a QC test at any time. The Contractor shall submit all QC test reports and summaries in writing, signed by the appropriate technician, the Department’s onsite representative by 1:00 P.M. on the next working day, except when otherwise noted in the QCP due to local restrictions. The Contractor shall make all test results, including randomly sampled densities, available to the Department onsite. Penalties for QCP non-compliance will be in accordance with Standard Specification 106.4.6 The Contractor shall cease recycling operations whenever one of the following occurs:
a.The computed yield differs from the mix design by 10 percen t or more.
b.The Contractor fails to follow the approved QCP.
c.The Contractor fails to achieve 98-percent density after corrective action has been taken.
d.The finished product is visually defective, as determined by the Resident. Recycling operations shall not resume until the Department approves the corrective action to be taken.
309.08 Test Strip The contractor shall assemble all items of equipment for the
recycling operation on the first day of the foamed asphalt work. The Contractor shall construct a test strip for the project at a location approved by the Resident. The Responsible onsite Recycling Supervisor will work with Department personnel to determine the 3-28 suitability of the mixed material, bitumen dispersion within the mixed material, moisture control within the mixed material, and compaction and surface finish. Thetest strip section is required to:
A.Demonstrate that the equipment and processes produce recycled layers to meet requirements specified requirements.
B.Determine the effect on the gradation of the recycled material by varying the forward speed of the recycling machine and the rotation rate of the milling drum.
C.Determine the sequence and manner of rolling necessary to obtain the compaction requirements and establish a target density. The Contractor and the Department will calibrate their respective gauges at this time. The test strip shall be at least 300 ft in length of a full lane-width (or a half-road width). Full recycling production will not start until a passing test strip has been accomplished. If a test strip fails to meet the requirements of this specification, the Contractor will be required to repair or replace the test strip to the satisfaction of the Resident. Any repairs, replacement, or duplication of the test strip will be at the Contractor’s expense. After the test strip has been pulverized, and the roadway brought to proper shape, the Contractor shall add water until it is determined that optimum moisture has been obtained. The test strip shall then be rolled using the specified compaction equipment as directed until the density readings show an increase in dry density of less than 1 pcf for the final four roller passes of each roller. The Contractor and Department will each determine a target density using their respective gauges by performing several additional density tests and averaging them. The average of these tests will be used as the target density of the recycled material for QC and Acceptance purposes. Following completion of the test strip, compaction of the material shall continue until a density of not less than 98 percent of the test strip target density has been achieved for the full width and depth of the layer. During the construction and compaction of the Full Depth Recycled base, should three consecutive Acceptance test results for density fail to meet a minimum of 95 percent of the target density, or exceed 102 percent of target density, a new test strip shall be constructed. ACCEPTANCE TEST FREQUENCY Property Frequency Test Method In-place Density 1 per 2000 ft / lane AASHTO T 310
309.09 Miscellaneous No new pavement shall be placed on the full depth recycled
pavement until a curing period of 48 hours has elapsed. If inclement weather occurs, the Department reserves the right to extend the curing period.
309.10 Method of Measurement Full Depth recycled material (with Foamed
Asphalt) will be measured by the yd2. 3-29
309.11 Basis of Payment The accepted quantity of Full Depth Recycled Pavement
with Foamed Asphalt shall be paid for at the contract unit price per yd2, complete in-place to the specified limits, which price shall be full compensation for furnishing all equipment and labor for pulverizing, blending, placing, grading, compacting and for all incidentals necessary to complete the work including asphalt binder, water, Portland Cement, lime, and crusher dust. The addition of materials to restore profile grade and/or cross-slope in areas shown on the plans or described in the construction notes will be paid separately under designated pay items within the contract. No additional payment will be made for materials salvaged from the project. Payments will be made under: P a y I t e m Pay Unit
309.35 Full Depth Recycled Pavement with Foamed Asphalt 5 in depth Square Yard
309.36 Full Depth Recycled Pavement with Foamed Asphalt 6 in depth Square Yard
Referenced in this section
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Source: Standard Specifications — Highways and Bridges, 2020 Edition. Pages 237–246 of 817. View official source ↗