Section_32_01_24_Hot_In-Place_Recycling.docx
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SECTION 32 12 15 HOT IN-PLACE RECYCLING
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SECTION 32 12 15
SECTION 32 12 15
HOT IN-PLACE RECYCLING
PART 1 GENERAL
1.1 SECTION INCLUDES
A. Products and procedures for hot in-place recycling of existing bituminous pavement using either single or multiple pass methods.
1.2 REFERENCES
The publications listed below form a part of this specification to the extent referenced. The publications are referred to within the text by the basic designation only.
A. ASTM C 117: Standard Test Method for Materials Finer than 75~um (No. 200) Sieve in Mineral Aggregates by Washing
| B. | ASTM C 136: Standard Test Method for Sieve Analysis of Fine and Coarse Aggregates |
| C. | ASTM D 75: Standard Practice for Sampling Aggregates |
| D. | ASTM D 140: Standard Practice for Sampling Bituminous Materials |
| E. | ASTM D 946: Penetration-Graded Asphalt Cement for Use in Pavement Construction |
F. ASTM D 1856: Recovery of Asphalt from Solution by Abson Method
| G. | ASTM D 2041: Theoretical Maximum Specific Gravity and Density of Bituminous Paving Mixtures |
| H. | ASTM D 2170: Kinematic Viscosity of Asphalts (Bitumen) |
| G. | ASTM D 2171: Viscosity of Asphalts by Vacuum Capillary Viscometer |
H. ASTM D 2172: Quantitive Extraction of Bitumen from Bituminous Paving Mixtures I. ASTM D 2726: Bulk Specific Gravity and Density of Non-Absorptive Compacted Bituminous Mixtures J. ASTM D 3381: Viscosity-Graded Asphalt Cement for Use in Pavement Construction K. ASTM D 3665: Random Sampling of Construction Materials L. ASTM D 4552: Classifying Hot-Mix Recycling Agents
| M. | COE CRD-C 649: Standard Test Method for Determining Percentage of Crushed Particles in Aggregate |
| 1.3 | SYSTEM DESCRIPTION |
| A. | Equipment, Tools, and Machines: |
| 1. | Maintain equipment, tools, and machines used in the performance of the work in a satisfactory working condition at all times, and in conformance with applicable governing regulations for local air pollution controls. |
| 2. | Provide equipment capable of performing recycling operations at a minimum rate of 720 square yards per hour to the depth required. |
| B. | Heating: Provide heating units that use radiant heat with no flame directly on the pavement. The combustion chamber shall be insulated and totally enclosed. Shield the heating units with an enclosed hood to hold in the heat and to protect workers and surrounding areas. |
| C. | Scariftying/Milling: |
| 1. | Provide scarifying or hot milling equipment that is able to penetrate the pavement surface so as to cut to the specified depth without tensile fracturing the aggregate in the pavement. When used for this purpose, the scarifiers or hot milling heads shall be able to thoroughly mix the recycled mixture with any material that is added as part of the recycling process. |
| 2. | Provide equipment with height adjustments to clear obstacles in the pavement. |
| D. | Distribution and Mixing: |
| 1. | Provide at least one unit of the recycling equipment capable of uniformly distributing and mixing the recycling agent and/or new asphalt concrete with the recycled material. |
| 2. | Distribution of the added material shall have a positive feed and shut-off linked to the movement of the unit. |
| 3. | The range of application shall be within that required for the project and should be controllable to plus or minus 0.05 gallons/square yard. |
| 4. | Heat the recycling agent, at the time of application, to within plus or minus 25 degrees F of the temperature of the recycled mixture. |
| E. | Placement: Provide a unit capable of spreading and leveling the recycled mixture uniformly across the processed width and with a vibratory or tamping screed to finish the recycled mixture surface. |
| F. | Straightedge: |
| 1. | Furnish and maintain at the site, in good condition, one 12 foot straightedge for each finishing unit (paver) for testing the finished surface. Make straightedges available for Government use. |
| 2. | Straightedges shall be constructed of aluminum or other lightweight metal, with blades of box or box-girder cross section with flat bottom, reinforced to insure rigidity and accuracy and with handles to facilitate movement on the pavement. |
1.4 SUBMITTALS
| A. | Samples: Samples. |
| B. | Test Reports: Field Testing and Sampling |
1.5 QUALITY ASSURANCE
| A. | Initial Sampling and Testing: |
| 1. | Perform sampling and testing using a commercial testing laboratory or Contractor's facilities, upon approval by the Contracting Officer. |
| 2. | Cost incurred for any subsequent inspection required because of failure of the facilities to pass the first inspection, will be at no additional cost to the Government. |
| B. | Samples: |
| 1. | Take recyclable asphalt pavement for laboratory tests in accordance with ASTM D 75. Submit a 400 lb sample of existing asphalt concrete. |
| a. | Where a single-pass remix process is used, a 200 lb sample of each new aggregate stockpile to make blended samples for the mix design, a 5 gal sample of asphalt cement, and a 5 gal sample of recycling agent. |
| 2. | Samples of recycling agents shall be taken in accordance with ASTM D 140. |
| 3. | Prior to the start of the work, obtain samples from the existing pavement from at least two locations to provide materials representative of the pavement. Use these samples to determine the amount of recycling agent required to achieve the mixture properties as provided in paragraph JOB-MIX FORMULA. Furnish the JMF to the Contracting Officer a minimum of 30 days prior to the start of recycling operations. |
| 1.6 | ENVIRONMENTAL REQUIREMENTS |
| A. | Perform hot in-place recycling procedures only when the existing pavement is dry and the pavement surface temperature is above 60 degrees F. |
| 1.7 | ACCEPTANCE |
| A. | Field Testing and Sampling |
| 1. | Perform field tests in sufficient numbers to ensure that the specifications are being met. |
| 2. | Submit copies of test results within 24 hours of material sampling. Submit copies of test reports on material properties of existing asphalt pavement, not less than 30 days before the material is required in the work. Include with the test reports information establishing compliance with the specifications detailed herein and in referenced publications. |
| 3. | Submit certified copies of the recycling agent manufacturer's test reports indicating compliance with applicable specified requirements, not less than 30 days before the material is required in the work. |
| 4. | Testing is the Contractor's responsibility to be performed by an approved commercial laboratory. Perform tests at the appropriate time; they will be the minimum acceptable for each type of operation. |
| B. | Mixture Properties |
| 1. | Single-Pass: |
| a. | Obtain a sample of the recycled mixture for every 2 hours of mix production. |
| b. | Extract the asphalt cement from the mix according to ASTM D 2172. The asphalt content of the recycled material shall be within the tolerance given in paragraph JOB-MIX FORMULA. |
| c. | Determine the gradation of the extracted aggregate according to ASTM C 117 and ASTM C 136. The extracted gradation shall meet the JMF and the corresponding tolerances. |
| 2. | Multiple-Pass: Record the amount of recycling agent used per day along with the square yard area recycled. Use these values to verify that the correct amount of recycling agent is being added to the recycled mixture. |
Table 1: Asphalt Binder Content Pay Factors
| Pay Factor |
| Mean Absolute Deviation from Job Mix Formula |
| 1.00 |
| 0.35 or less |
| 0.98 |
| 0.36 to 0.50 |
| 0.95 |
| 0.51 to 0.75 |
| 0.90 |
| 0.76 to 1.00 |
| Reject |
| Above 1.00 |
Table 2: Aggregate Gradation Pay Factors
| Sieve Size |
| Pay Factor |
| Mean Absolute Deviation |
| 1/2 inch and larger |
| 1.00 |
| 0.0 to 5.6 |
| 0.98 |
| 5.7 to 6.3 |
| 0.95 |
| 6.4 to 7.0 |
| 0.90 |
| 7.7 to 7.7 |
| 0.85 |
| 7.8 to 8.4 |
| Reject |
| Over 8.4 |
| 3/8 inch |
| 1.00 |
| 0.0 to 5.4 |
| 0.98 |
| 5.5 to 6.4 |
| 0.95 |
| 6.5 to 6.8 |
| 0.90 |
| 6.9 to 7.5 |
| 0.85 |
| 7.6 to 8.4 |
| Reject |
| Over 8.4 |
| No. 4 |
| 1.00 |
| 0.0 to 5.2 |
| 0.98 |
| 5.3 to 5.8 |
| 0.95 |
| 5.9 to 6.4 |
| 0.90 |
| 6.5 to 7.0 |
| 0.85 |
| 7.1 to 7.6 |
| Reject |
| Over 7.6 |
| No. 8 |
| 1.00 |
| 0.0 to 4.3 |
| 0.98 |
| 4.4 to 4.8 |
| 0.95 |
| 4.9 to 5.3 |
| 0.90 |
| 5.4 to 5.8 |
| 0.85 |
| 5.9 to 6.4 |
| Reject |
| Over 6.4 |
| No. 50 |
| 1.00 |
| 0.0 to 3.4 |
| 0.98 |
| 3.5 to 3.8 |
| 0.95 |
| 3.9 to 4.1 |
| 0.90 |
| 4.2 to 4.4 |
| 0.85 |
| 4.5 to 4.9 |
| Reject |
| Over 4.9 |
| No. 200 |
| 1.00 |
| 0.0 to 1.8 |
| 0.98 |
| 1.9 to 2.0 |
| 0.95 |
| 2.1 to 2.2 |
| 0.90 |
| 2.3 to 2.4 |
| 0.85 |
| 2.5 to 2.6 |
| Reject |
| Over 2.6 |
| C. | Density Testing |
| 1. | Depth of recycling less than 1.5 inch: Obtain one 6 inches core sample for each 1,000 square yards of hot in-place recycled mixture. |
| 2. | Depth of recycling exceeds 1.5 inch: Obtain one 4 inches core sample for each 1,000 square yards of hot in-place recycled mixture. |
| 3. | Determine the location of the core samples according to ASTM D 3665. |
| 4. | The density of the cores shall be determined according to either COE CRD-C 650 or ASTM D 2726. The cores shall have a density equal to 91 to 94 percent of the theoretical maximum specific gravity determined according to ASTM D 2041. |
Table 3: Density Pay Factors
| Pay Factor |
| Density, in Percent (ASTM D 2041) |
Average Density
| Reject |
| More than 96 |
| 0.80 |
| 94.1 to 96 |
| 1.00 |
| 91 to 94 |
| 0.90 |
| 90 to 90.9 |
| Reject |
| Less than 90 |
| D. | Grade Conformance |
| 1. | Test the finished surface of the recycled pavement, for conformance with the plan-grade requirements and acceptance in the presence of the Contracting Officer, by running lines of levels at intervals of 25feet longitudinally and transversely for airfield pavements and at intervals of 100 linear feet per lane or part thereof for roadways and parking lots to determine the elevation of the completed pavement. The finished surface shall not vary more than 0.05 foot from the established plan grade line and elevation. |
| 2. | Finished surfaces at junctures with other pavements shall coincide with finished surfaces of abutting pavements. |
Table 4: Grade Pay Factors
| Pay Factor |
| Percent of Measurements Out of Grade Tolerance |
| 1.00 |
| Less Than 5.0 |
| 0.95 |
| 5.0 |
| 0.90 |
| 5.1 to 10.0 |
| 0.80 |
| 10.1 to 20.0 |
| 0.70 |
| 20.1 to 30.0 |
| 0.60 |
| 30.1 to 49.9 |
| Reject |
| 50 or More |
| E. | Surface Smoothness |
| 1. | After completion of the recycling operation, the finished surface will be tested by using the straightedge. Location and deviation from straightedge of all measurements will be recorded. Other approved devices may be used provided that, when satisfactorily and properly operated, such devices reveal all surface irregularities exceeding the tolerances specified. |
| 2. | Correct surface irregularities that depart from the testing edge by more than 1/4 inch as directed. |
| PART 2 | PRODUCTS |
2.1 RECYCLING AGENTS
| A. | The asphalt-rejuvenating agent shall be composed of petroleum resin oil base capable of increasing the ductility, penetration and durability of the asphalt binder in the recycled asphalt. |
| B. | A letter of compliance from the manufacturer that certifies the material conforms to the manufacturer specifications shall accompany each shipment delivered to the project. |
| 2.2 | JOB-MIX FORMULA (JMF) |
| A. | Furnish, for acceptance, a JMF to the Contracting Officer meeting the requirements of |
| 1. | Roads and Parking Lots: Section 32 12 16 HOT-MIX ASPHALT FOR ROADS. |
| 2. | Airfields: Section 32 12 15 HOT-MIX ASPHALT (HMA) FOR AIRFIELDS. |
| 3. | The Contracting Officer will verify this JMF through test results of samples of materials submitted by the Contractor. |
| B. | No payment will be made for hot in-place recycled mixtures produced prior to the Government review of the JMF. The JMF will indicate the gradation of the aggregate and a definite percentage of asphalt and recycling agent to be added to the mixture. |
| C. | Develop the JMF by combining various percentages of the selected recycling agent with the existing pavement material. Increase the amount of recycling agent in the recycled mixture until the void content of specimens made according to COE CRD-C 649 decreases below 3.5 percent. This will provide the maximum amount of recycling agent that can be added to the mixture. At this maximum amount, and at least one lower percentage of recycling agent, extract the asphalt cement from the samples made and recovered according to ASTM D 2172 and ASTM D 1856, respectively. |
| D. | Obtain the viscosity of the recovered asphalt cements in accordance with either ASTM D 2170 or ASTM D 2171. The amount of recycling agent used in the recycled mixture shall be the amount that results in an asphalt viscosity equivalent to ASTM D3381, Grade AC-20 or that which results in a minimum void content of 3.5 percent. |
| E. | The JMF will allow an asphalt content tolerance of plus or minus 10 percent of the amount specified in the JMF. |
| 2.3 | EQUIPMENT |
| A. | Recycling Equipment: |
| 1. | The recycling equipment unit used for collecting the existing asphalt concrete together, adding the new rejuvenating agent, mixing and paving the recycling mix in a continuous process shall be self-contained, self-propelled unit designed for this purpose. |
| 2. | For the purpose of this contract, the self-containment requirement for the recycling unit shall mean once the existing asphalt pavement is sheared, it remains contained in the recycling unit, and shall be immediately mixed with the rejuvenating agent. The recycled asphalt pavement shall not be exposed to atmospheric conditions except when placed for compaction. |
| 3. | The heating units shall be of sufficient capacity to heat the pavement material as necessary for efficient processing, but be designed as to minimize the damage to the asphalt binder. The heating system shall also have provisions for cooling the asphalt surface to 350 degrees F). |
| 4. | The recycling unit shall be capable of loosening the heated asphalt pavement to the specified depth in a uniform pattern, loading existing asphalt and adding heated rejuvenator into a heated mixing plant for a minimum of 30 seconds. The recycling unit shall then be capable of placing and leveling the recycling asphalt pavement in a condition for immediate re-compaction. |
| a. | The rate of application of the rejuvenating agent shall be adjustable to maintain the appropriate application rate in the relation to the operating speed of the machine. Metering devices shall be incorporated into the distribution systems for recording the quantities of asphalt rejuvenating agent. The mixing shall take place in a heated rotating drum mix plant for at least 30 seconds in such a manner as to ensure complete blending. |
| b. | The recycling unit shall also have an adjustable, heated, vibratory screed capable of placing the mixture to the required cross-section, profile and alignment. Compaction equipment shall meet these applicable requirements. |
| B. | Compaction Equipment: Compaction shall be accomplished with an 8 to 10-ton steel wheel roller in vibratory and/or static mode as needed. |
| 1. | The roller shall be equipped with an adequate scraping or cleaning device on each wheel to prevent the accumulation of material on the wheels. |
| 2. | The roller shall be equipped with a water system that will keep all wheels uniformly wet to prevent material pickup when required. |
| PART 3 | EXECUTION |
| 3.1 | SURFACE PREPARATION |
| A. | Prior to recycling, clean the pavement surface of all loose and foreign or objectionable material with brooms or other suitable methods. Localized patching, structural corrections, and adjustments to existing structures (i.e., manhole covers) should be completed prior to the recycling process. |
| 3.2 | HEATING |
| A. | Provide heating units of sufficient number and size to heat the pavement surface as required for successful scarifying and/or hot milling to the required depth. |
| B. | Do not allow these units to overheat the existing pavement. Generate sufficient heat to result in a minimum recycled mixture temperature of 240 degrees F as the mixture is being placed. |
| C. | The maximum temperature of the recycled mixture should not exceed 290 degrees F at any time during the recycling process. |
| 3.3 | RECYCLING PROCEDURE |
| A. | Contractor shall use either the Single-Pass or the Multiple-Pass Method as indicated within the Scope of Work. |
| B. | Single-Pass: |
| 1. | Perform the single-pass method consisting of self-contained, self-propelled, automated units capable of heating, scarifying and/or hot rotary mixing and redistributing the recycled mixture. |
| 2. | The mixture shall consist of the existing pavement, recycling agent, and new asphalt concrete to the specified depth and design (Remixing). |
| a. | Automatically feed the reclaimed material into a mixing unit. Add a recycling agent and, when required, new asphalt concrete to the reclaimed material at the mixer. |
| b. | Specify the type and quantity of the new asphalt concrete and the proportion of new material and reclaimed material in the JMF. |
| c. | Thoroughly mix all materials for at least a minimum of 30 seconds while maintaining the minimum temperature of 300 degrees F. |
| d. | After mixing, the combined bituminous material shall be gathered by a leveling device equipped with augers for mixing and placement to a uniform depth over the width being processed (Repaving)]. |
| 3. | Place a layer of new hot bituminous pavement material conforming to the JMF over the recycled mix while it still has a residual minimum temperature of 225 degrees F. This layer shall be automatically fed into a finishing unit (paver) which has automatic screed control for longitudinal leveling of the homogeneous recycled mixture to the required thickness in conformance with the specified cross-section. |
| C. | Multiple-Pass: |
| 1. | Perform the multiple-pass method consisting of self-contained, self-propelled or towed, automated units capable of heating, scarifying and/or hot rotary mixing, redistributing, and screeding. |
| 2. | The equipment used in the method shall also provide for controlled leveling at the crown and across the screed to insure a cross-section that conforms to the pavement profile specified. |
| 3. | Control the heating to provide a minimum recycled mixture temperature of 240 degrees F behind the screed. |
| 4. | The unit shall be able to uniformly distribute the specified amount of recycling agent throughout the recycled mixture. |
| 5. | Apply a wearing course meeting the requirements of Section 32 12 16 HOT-MIX ASPHALT FOR ROADS or Section 32 12 15 HOT-MIX ASPHALT (HMA) FOR AIRFIELDS following completion of the recycling process. |
| 3.4 | JOINTS |
| A. | Heat the existing pavement a minimum of 4 inches beyond the width of the recycling. |
| B. | When recycling adjacent to an existing hot-mix recycled pavement mat, the heating shall extend 6 inches into the existing mat and at least 4 inches of this mat shall be recycled with the new mat. |
| 3.5 | COMPACTION |
| A. | The density achieved during compaction shall be 91 to 94 percent of the theoretical maximum specific gravity as determined according to ASTM D 2041. |
| 3.6 | TEST SECTION |
| A. | Prior to the start of the recycling, recycle a length of pavement at least 50 feet long to the depth required in the project. At the direction of the Contracting Officer, place this test section in two adjacent paving lanes to demonstrate joint construction. |
| B. | Recycled mixture shall be placed or spread and rolled with the equipment to be used in the project and in accordance with requirements specified above. |
| C. | This test section will be tested and evaluated as a full days production and shall conform to all specification requirements. The test section may be located in one of the less critical areas of the project pavement construction, as directed by the Contracting Officer. |
| D. | Begin full production if tests results are satisfactory, and as approved by the Contracting Officer. |
| E. | If the test section was constructed within the project boundaries, keep it in place as part of the completed pavement. |
| D. | If tests indicate that the pavement does not conform to specification requirements, make necessary adjustments to operations and procedures immediately, and construct another test section, all at no additional cost to the Government. |
| F. | Construct additional test sections, as necessary and as directed by the Contracting Officer, to be sampled and tested for conformance with specification requirements. Do not start full production without test section approval by the Contracting Officer. |
| 3.7 | TRAFFIC |
| A. | Traffic shall not be allowed on the compacted pavement until it has cooled sufficiently to prevent dislodging of the aggregate. Any areas damaged by traffic shall be repaired as directed by the Contracting Officer at no additional cost to the Government. |
END OF SECTION
HOT IN-PLACE RECYCLING Page 7
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