4-80 Section 415 – Cold Central Plant Recycling
415.01 DESCRIPTION . This work shall consist of cold central plant recycling (CCPR) of the existing pavement surface, including generating RAP material from the project or other sources, adding additional asphalt emulsion or foamed asphalt binder, Portland cement, virgin aggregate, and mixing and repaving of the material to the depths, lines, an d grades shown on the Plans. Excess recycled material not used in the CCPR process will become the property and responsibility of the Contractor. 415.02 MATERIALS . Materials shall meet the requirements of the following subsections: Portland Cement ................................ ................................ ................................ ......... 701.02 Performance -Graded Asphalt Binder ................................ ................................ ......... 702.01 Anionic Emulsified Asphalt ................................ ................................ ....................... 702.02(a) Cationic Emulsified Asphalt ................................ ................................ ...................... 702.02(b) Aggregate for Bituminous Concrete Mixtures ................................ ........................... 704.10 Recycled Asphalt Pavement ................................ ................................ ...................... 704.22(a) Water ................................ ................................ ................................ .......................... 745.01 Emulsified asphalt for CCPR, when used, shall be type HFMS -2, HFMS -2h, HFMS -2s, CSS -1, CSS -1h, MS-2h, or as recommended by the Contractor as a result of the design criteria of this specification and approved by the Engineer. Foamed asphalt binder for CCPR, when used, shall be unmodified and grade 58S -28, unless otherwise specified in the Contract. The CCPR shall meet the gradation requirements of Table 415.0 2A for extracted aggregate ( AASHTO T 30, dry) taken from the pulverized material. TABLE 415.02A – EXTRACTED AGGREGATE GRADATION Sieve Designation Percentage by Mass (Weight) Passing Square Mesh Sieves 1-1/2 inch (37.5 mm) 100 1 inch (25.0 mm) 90 – 100 No. 4 (4.75 mm) 30 – 70 No. 200 ( 0.075 mm) 0 – 12
4-81 The CCPR shall be free of any materials not generally considered to be asphalt pavement. If the processed
material does not meet the gradation requirements as specified, additional virgin aggregates shall be added at a rate such that the blended mixture co nforms to the gradation requirements specified in Table 415.02A . Additional virgin aggregate shall meet the requirements of Subsection 704.10(a) and Subsection 704.10(b) , except that sand equivalent is not required. 415.03 EQUIPMENT .
a.General Requirements . The Contractor shall furnish equipment which is capable of mixing, crushing, or screening the processed bituminous material and any virgin material, foamed asphalt or emulsion, and Portland cement into a homogeneous mixture. The mixing equipment shall be equipped with belt scales to accurately proportion the additives, adjusted by the moisture content of the processed RAP and aggregate. The belt scale shall be verified for accuracy at each new location prior to mix production and shall be verified during production at the request of the Enginee r. The method of depositing the mixed material shall be such that segregation does not occur. Any additional equipment used by the Contractor beyond th at specified below shall be approved by the Engineer based on its suitability to produce results meeting the specification requirements. Hauling equipment used for hauling the mixture shall meet the requirements of Subsection 406.05(a) . Pavers shall meet the requirements of Subsection 406.05(b) .
b.Compaction Equipment . The number, mass, and type of rolle rs shall be sufficient to obtain the required uniform density, full depth, while the mixture is in a workable condition. A pneumatic - tired roller shall perform the initial rolling after the emulsion initially breaks (indicated by color change from brown to black). At a minimum, the following rollers shall be used:
1.At least one double drum vibratory roller with a minimum weight of 10 tons.
2.At least one pneumatic -tired roller with a minimum weight of 22 tons. Rollers shall have a width of not less t han 65 inches. Tires on pneumatic rollers shall be evenly inflated and matched in size and profile so as to maximize compactive effort.
4-82 415.04 Construction Requirements .
a.General Requirements . For quantity calculation and construction purposes, a Portland cement content of 1.0% was used to estimate the required Portland cement tonnage for this work. Agency personnel and equipment shall be allowed free and full access to the project site at n o additional compensation due the Contractor to allow for any and all sampling required to assess compliance with the provisions of this specification. The Contractor will afford the Agency all traffic control operations and provide means to extract sample s as requested to achieve this effort. The residual asphalt and cement content used in production may vary throughout the project and be adjusted by the Contractor based on the results of QC testing or other variables as identified by the Agency or the C ontractor to maintain an optimized finished product. Emulsion or foamed asphalt binder, water, processed bituminous pavement, virgin aggregate, and Portland cement shall be added in the proportions necessary to meet mix design requirements and verified b y tank checks performed in accordance with the minimum quality control frequencies. Portland c ement may be introduced in dry form or as a cement slurry.
b.Design Criteria . The CCPR shall meet the design criteria requirements of Table 415.04A , Table 415.0 4B, or Table 415.04C , as applicable for the type of asphalt being used. TABLE 415.04A – EMULSIFIED ASPHALT USING THE MARSHALL STABILITY TEST Criteria Test Method Requirement Ratio of residual asphalt to cement -- 3 to 1, min. Stability value, dry subset AASHTO T 245 1,500 lbf , min. Retained stability, wet/dry subsets AASHTO T 245 0.70, min. TABLE 415.04B – EMULSIFIED ASPHALT USING THE INDIRECT TENSILE STRENGTH TEST Criteria Test Method Requirement Ratio of residual asphalt to cement -- 3 to 1, min. Indirect tensile strength, dry subset AASHTO T 283 45 psi , min. Tensile strength ratio AASHTO T 283 0.70, min.
4-83 Table 415.04c – Foamed Asphalt
Criteria Test Method Requirement Ratio of residual asphalt to cement -- 3 to 1, min. Foamed asphalt expansion ratio -- 8 times , min. Foamed asphalt half -life -- 6.0 sec. , min. Indirect tensile strength, dry subset AASHTO T 283 45 psi , min. Tensile strength ratio AASHTO T 283 0.70, min.
c.Mix Design . The Contractor shall develop a CCPR mix design consisting of RAP, emulsified asphalt or foamed asphalt, Portland cement, and blended aggregate if appropriate. To obtain material to conduct mix designing, the Contractor shall sample exi sting pavement to represe nt the recycled aggregates that would be expected to result from the milling process. A minimum of four samples representative of the quarter points of the entire length of the project shall be taken . If stockpiled RAP is to be used, the stockpile will be sampled from 4 locations and combined to generate a representative sample. The Contractor shall develop and submit a material sampling plan for review and approval by the Agency a minimum of 5 working days prior to obtaining CCPR mix design samples. At a minimum, the sampling plan shall include the number of samples, location of samples, and the method of sampling and backfilling. The mix design shall also consider shoulder areas to be widened beyond existing edge of pavement such that the recycled bitumin ous pavement is full width to the lines and grades shown in the Plans. When emulsified asphalt is used, AASHTO PP 86 shall be the method used to develop a mix design in accordance with AASHTO MP 31 , except only meeting the specified design requirements in Table 415.04A or Table 415.04B , as applicable. The job mix formula (JMF) shall contain the percent passing each sieve, emulsified asphalt type and content as a percent of total CCPR material, and cement content as a percent of total CCPR material. When foamed asphalt is used, AASHTO PP 94 shall be the method used to develop a mix design in accordance with AASHTO MP 38 , except only meeting the specified mix design requirements in Table 415.04C . The job mix formula shall contain the percent passing each si eve, foamed asphalt content as a percent of total CCPR material, and cement content as a percent of total CCPR material.
4-84 A minimum of 10 working days shall be allowed for evaluation of the submitted mix design. A
copy of all test data used in develop ing the mix design, including graphs, shall be submitted with the mix design. The established job -mix formula is valid until a change is made in aggregate source, cement content, or emulsion source. No change in the job -mix formula may be made without the written approval of the Engineer. The Engineer may approve changes in the design’s job -mix formula or discontinue use of the design if placement, finishing, or compaction characteristics are determined to be unsatisfactory.
d.Placing . The mix shall be paved full width, including shoulders where paved shoulders existed or where the shoulders are widened, to the specified grade and slope. The bituminous mixture shall be placed and finished with the specified equipment, shall be struck o ff in a uniform layer to the full width required and of such depth that each course, when compacted, shall have the required thickness, and shall conform to the grade and elevation specified. The finished surface shall be of uniform texture and evenness an d shall not show tearing, shoving, or pulling of the mixture. In areas where irregularities or unavoidable obstacles make the use of mechanical placing and finishing equipment impracticable, the mixture shall be spread, raked, luted, and compacted by hand methods.
e.Compaction . Compaction shall be performed while the emulsion or foamed asphalt is in a workable state. The CCPR material shall be finished within a grade tolerance of ± 1/2 inch, provided that this deviation is not maintained for a distance l onger than 50 feet, and provided that the required crown or superelevation is maintained. Deviations in the finished surface shall not exceed ± 3/8 inch in any direction using a 10 foot minimum straight edge. Any repairs required to correct surface devia tions are at the Contract or’s expense using Agency approved material and methods. The CCPR shall be compacted to 98% to 102% of the target maximum density (TMD). If two out of three consecutive density test results are outside of the allowable range, the Contractor will be required to construct a new test section to establish an updated TMD. If the Engineer determines that the TMD is apparently incorrect, as evidenced be being achieved with little or minim al compactive effort, then the Engineer will req uire a new test section to establish a new TMD.
4-85 (f) Curing and Stability . The CCPR may be opened to traffic after achieving the target density and
after the material is determined to be stable by the Engineer. Hot mixed bituminous concrete pavements shall not be placed until the CCPR material has been allowed to cure and the free moisture content is reduced to a maximum of 1.5% every 1,000 feet per lane or as directed by the Engineer. The Engineer may waive the 1.5% free moisture content in such cases that the CCPR has been open to a cure period of 14 days or more. The required density shall be achieved and maintained until a wearing course pavement has been placed. Any additional compaction effort or repair of imperfections in the CCPR mat erial shall be performed as directed by the Engineer at no additional cost to the Agency. As an alternative for the purpose of protecting the CCPR from damage due to traffic, the Engineer may approve the use of an emulsified asphalt fog seal after the plac ement of the CCPR and prior to the placement of any hot mix bituminous pavement.
g.Weather and Seasonal Limitations . CCPR shall not be performed when the ambient air temperature is below 50°F, when the overnight temperatures are expected to be below 50°F , when the temperature of the existing roadway surface is below 50°F, when the weather is foggy or rainy, or when weather conditions or predicted weather conditions are such that proper mixing, spreading, and compacting of the recycled material cannot be a ccomplished. The placement of CCPR shall not be performed prior to May 1st or after September 15th. When it is in the public interest for servicing traffic, the Engineer may adjust the ambient air or existing roadway surface temperature requirements or e xtend the dates of the recycling season. 415.05 QUALITY CONTROL .
a.General Requirements . The Contractor shall be responsible for performing all process control and quality control sampling and testing and operate in accordance with an approved QC plan. Prior to performing any CCPR production, the Engineer or the Contractor may request a pre -recycle conference to discuss the recycling schedule. The Contractor shall sample, test, and evaluate the CCPR process in accordance with the procedures and minimum frequencies specified in Table 415.05A .
4-86 Table 415.05a – Minimum Quality Control Frequencies
Test or Action Frequency Test Method Density 1 per 1,000 feet per lane AASHTO T 355 or ASTM D2950 Air temperature 4 per day at even intervals Verified thermometer Surface temperature At beginning and end of each day’s operation Verified thermometer Yield for cement and emulsion 2 per day at even intervals Tank check RAP moisture 1 per day AASHTO T 217 or AASHTO T 255 Aggregate moisture 1 per day AASHTO T 217 or AASHTO T 255 In-place moisture content 3 per day AASHTO T 217 , AASHTO T 255 , AASHTO T 310 , or ASTM D7830 Gradation and asphalt content of final product 1 per day AASHTO T 30 (dry), AASHTO T 164 , or AASHTO T 308 Density testing shall be the average of three points across the lane (transverse) for each testing location. Gradation failures shall require the Contract or to take action to adjust the process to achieve compliant material. Additional virgin aggregate added to correct gradation shall meet the requirements of Subsection 704.10(a) and Subsection 704.10(b) , except that sand equivalent is not required. Qualit y control records shall include all sampling events, testing events, and process changes with accurate time and location data. The Contractor shall submit QC records and summaries to the Engineer by 1:00 p.m. on the next working day. The Contractor shall m ake all test results, including randomly sampled densities, available to the Engineer onsite and on request.
4-87 The Contractor shall cease recycling operations whenever one of the following occurs:
1.The computed yield of each additive differs from the approved JMF by 10% or more.
2.The Contractor fails to follow the approved QC plan.
3.The finished product is visually segregated, unstable, or otherwise defective, as determined by the Engineer. Recycling operations shall not resume until the Contactor and the Agency agree on the corrective action to be taken.
b.Quality Control Plan . The Contractor shall submit a quality control plan (QC plan) to the Engineer a minimum of 14 calendar days prior to initiating CCPR operations and shall not commence CCPR operations until the QC plan is accepted by the Engineer. The QC plan shall address any items that affect the quality of the recycling proces s including, but not limited to, the following:
1.QC Plan Administrator . The QC plan administrator shall be identified in the QC plan and shall list their past experience on CCPR projects. They shall:
a.Be a full -time employee of the Contractor or an in dependent consultant not involved with the acceptance activities of the project .
b.Have a minimum of four years of experience in quality control activities in construction operations .
c.Have full authority to institute actions necessary for successful im plementation of the QC plan.
2.Quality Control Technician . The quality control technicians (QCT) shall be responsible for conducting quality control and inspection activities to implement the QC plan. There may be more than one QCT on a project. They sha ll:
4-88 a. Be a full -time employee of the Contractor or an independent consultant with a
minimum of two years of experience in quality control activities in field construction operations .
b.Have completed the requirements for the applicable testing by the Northeast Transportation Training and Certification Program (NETTCP) for Soils and Aggregate Inspector, or an equivalent regional program .
c.Have full authority to institute actions necessary for successful implementation of the QC plan.
3.Recycling Supervisor . The recycling supervisor shall be responsible for conducting controlling the recycling process, quality control and inspection activities at the mixing plant to implement the QC plan. They shall:
a.Be a full -time employee of the Co ntractor or an independent consultant with a minimum of two years of experience in quality control activities in field construction operations .
b.Have full authority to institute actions necessary for successful implementation of the QC plan.
4.Minimum Quality Control Parameters . Minimum quality control parameters are:
a.Methods to adhere to the JMF.
b.Mixing details, pugmill type, production rates, and material processing.
c.Make and type of pavers.
d.Make, type, of rollers, and their respective loc ation within the paving train.
e.Process control testing and quality control testing. Daily QC testing results shall be submitted to the Engineer as requested and copies of all project QC testing shall be submitted on such dates that a biweekly estimate f rom the Agency is intended to be processed.
4-89 f. Transportation, including the process for ensuring that truck bodies are clean and
free of debris or contamination that could adversely affect the finished product, and the type of release agent used (if required).
g.Laydown operations, including procedures for mix design modification, avoiding recycling and curing in inclement weather, avoiding damage from haul trucks, material yield monitoring, methods to ensure that segregation is minimized, longitudin al joint construction, procedures to determine the maximum rolling and placing speeds based on field quality control, and achieving the best possible smoothness.
h.Methods for protecting the finished product from damage and procedures for any necessary c orrective action.
i.Methods of grade checks.
j.Examples of QC plan and logbook forms.
k.Methods for calibration or verification of density gauge.
l.Stockpile management procedures.
c.Control Section . Control sections shall be con structed to establish the TMD at the beginning of the CCPR, and through the project as needed. The Contractor shall construct a control section to assure the Engineer that the Contractor’s equipment and procedures are suitable for the work specified and esta blish the target maximum density and moisture content. The rolling pattern shall be determined from buildup, when the density readings show an increase in dry density of less than 1 pcf for the final four roller passes of each roller. The average of a min imum of 10 tests taken throughout the control section after the buildup is complete shall be used to determine the TMD. If agency personnel are available, their values shall be included in the average, or used to establish the density gauge offsets, as di rected by the Engineer. The control section shall be full lane width and a minimum of 500 feet long, or as approved by the Engineer. No further recycling shall be performed until all aspects of the control section and the TMD are approved by the Engineer . The Contractor shall use the same equipment for building both the accepted test sections and performing the CCPR work on the project unless equipment substitution is approved by the Engineer.
4-90 The Engineer may require an additional test section and addi tional process control sampling to
investigate the suitability of substituted or changed equipment. If the control section does not meet the requirements of this specification, or the target density is not determined from buildup testing, then the Contract or shall modify the procedure and either construct another test section or reconstruct the original test section until suitable results are obtained. 415.06 METHOD OF MEASUREMENT . The quantity of Cold Central Plant Recycling of the depth specified to be m easured for payment will be the number of square yards of existing pavement which has been recycled in an acceptable manner as determined by actual surface measurements of the lengths and widths of the recycled area as shown on the Plans or as directed by the Engineer. No additional compensation will be made for overlapping areas. The quantity of Aggregate for CCPR to be measured for payment will be the number of tons used in the complete and accepted work. The quantity of Portland Cement for CCPR to be mea sured for payment will be the number of tons of material in place in the complete and accepted work, as determined from the load tickets or other method as approved by the Engineer. The quantity of Emulsified Asphalt for CCPR and Foamed Asphalt for CCPR to be measured for payment will be the number of hundredweight used in the completed and accepted work. 415.07 BASIS OF PAYMENT . The accepted quantity of Cold Central Plant Recycling of the depth specified will be paid for at the Contract unit price per square yard. Payment will be full compensation for performing the work specified and for furnishing all labor, materials, tools, equipment, and incidentals necessary to complete the work. Any additional RAP material, not generated from the project, required to meet the project volume of Cold Central Plant Recycling will not be paid for separately but will be considered incidental to Cold Central Plant Recycling. The accepted quantity of Aggregate for CCPR will be paid for at the Contract unit price per ton. Payment will be full compensation for furnishing and placing the material specified and for furnishing all labor, tools, equipm ent, and incidentals necessary to complete the work. Payment for the furnishing of emulsified asphalt fog seal will be made under the appropriate Section 404 pay item in the Contract.
4-91 The accepted quantity of Portland Cement for CCPR will be paid for at the Contract unit price per ton.
Payment will be full compensation for furnishing and placing the material specified and for furnishing all labor, tools, equipment, and incidentals necessary to complete the work. The accepted quantity of Emulsified Asph alt for CCPR and Foamed Asphalt for CCPR will be paid for at the Contract unit price per hundredweight for the specified material applied. Payment will be full compensation for furnishing, transporting, and placing the material and for furnishing all labor , tools, equipment, and incidentals necessary to complete the work. Payment will be made under: Pay Item Pay Unit 415.0200 Cold Central Plant Recycling, 2 Inch Depth ................................ ............. Square Yard 415.0250 Cold Central Plant Recycling, 2.5 Inch Depth ................................ .......... Square Yard 415.0300 Cold Central Plant Recycling, 3 Inch Depth ................................ ............. Square Yard 415.0350 Cold Central Plant Recycling, 3.5 Inch Depth ................................ .......... Square Yard 415.0400 Cold Central Plant Recycling, 4 Inch Depth ................................ ............. Square Yard 415.0450 Cold Central Plant Recycling, 4.5 Inch Depth ................................ .......... Square Yard 415.0500 Cold Central Plant Recycling, 5 Inch Depth ................................ ............. Square Yard 415.5100 Aggregate for CCPR ................................ ................................ ................. Ton 415.5200 Portland Cement for CCPR ................................ ................................ .......Ton 415.5300 Emulsified Asphalt for CCPR ................................ ................................ ...Hundredweight 415.5400 Foamed Asphalt for CCPR ................................ ................................ .......Hundredweight
4-92 Sectio N 417 – Bituminou S Crac K Sealing
417.0 1 DESCRIPTION . This work shall consist of furnishing and placing crack -sealing material in the cracks of existing bituminous concrete pavement. 417.0 2 MATERIALS . Materials shall meet the requirements of the following subsection s: Joint Sealer, Hot Poured ................................ ................................ ............................ 707.0 2(a) The Contractor shall provide the Engineer with a copy of the material manufacturer’s recommendations pertaining to heating, application, and reheating prior to the beginning of operations or the changing of material s. 417.0 3 EQUIPMENT . Equipment shall mee t the approval of the Engineer and shall always be maintained in working condition.
a.Air Compressor . Air compressors shall be portable and capable of furnishing at least 100 cubic feet of air per minute with a minimum pressure of 90 psi at the nozzle . The compressor shall be equipped with traps that will keep the compressed air free of any oil or water.
b.Hand Tools . Hand tools shall consist of brooms, shovels, metal bars with chisel -shaped ends, squeegees, and any other tools which may be req uired to accomplish the work .
c.Melting Kettle . The melting kettle shall be a double boiler, indirect -fired portable type. The space between the inner and outer shells shall be filled with a suitable heat transfer oil or substitute having a flash point of not less than 531°F . The kettle shall be equipped with a satisfactory means of agitating the joint sealer . This may be accomplished by continuous stirring with mechanically operated paddles or by a continuous circulating gear pump attached to the heatin g unit. The melting kettle shall be equipped with a thermostatic control calibrated between 200°F and 550°F . The kettle shall be mounted on rubber tires and be equipped with a metal shield beneath the firebox to protect the pavement.
d.Application Wand . The application wand shall apply a controlled flow of material via an insulated or heated hose . The nozzle shall distribute the material as called for on the Plans or this specification . The Contractor shall backflush the hose and applicator wand any time the application of sealant has been delayed for a period greater than 15 minutes. A pressure regulator shall be provided to regulate pressure at the nozzle . A bypass line into the holding tank is required for use when the nozzle is shut off.
Source: Vermont Standard Specifications for Construction, 2024 Edition. Pages 398–409 of 1,380.