164device shall be built into the tank or the recirculating or discharge line so that a sample can be drawn during circulation or discharge.
2.All shipping documents shall contain sufficient information such that at any point, the material may be traceable back to the original test results. If the material is mixed with other approved material for storage, the record system will be such as to assure the traceability of all the material which is being mixed.
3.All shipping documents shall be accompanied by a statement similar to “We certify that all material being shipped on this invoice/bill of lading has been tested and approved under the Virginia Asphalt Acceptance Program and that the material has been loaded under the supervi - sion of our representative into carriers that are suitable for shipment of this material.”
4.All shipping documents shall be kept by the recipient of the material and are available for verification by VDOT personnel.
5.Only material tested and certified in accordance with the V AAP and on VDOT approved product lists shall be mixed and shipped to VDOT projects.
b.Storing: Asphalt material shall be placed in storage tanks that are free from contamination. Emul- sified asphalts stored longer than 30 days from the shipping date on the Bill of Lading shall be retested in accordance with Section 210.04 to verify the material still meets product specifications.
210.06 Payment Adjustment System
If the asphalt material represented by any one sample does not conform to the requirements herein and the material is a pay item, the Engineer will reduce the Contract unit price for the item by 4 percent for each property that does not conform to the Specifications for the quantity represented by the sample that was used on the project. The Engineer will reject any unused material represented by the failing sample. The Engineer will consider any failed sampled asphalt material that is not a pay item unacceptable and subject to the provisions of Section 105.18 and Section 106.10. SECTION 211—ASPHALT CONCRETE
211.01 Description
Asphalt concrete shall consist of a combination of mineral aggregate and asphalt material mixed mechan - ically in a plant specifically designed for such purpose. An equivalent single-axle load (ESAL) will be established by the Engineer, and SUPERPA VE mix types may be specified as one of the types listed as follows:210.05 165 Mix Type Equivalent Single-Axle Minimum Asphalt Aggregate Load (ESAL) Range Performance Grade Nominal (millions) (PG)1 Maximum Size2 SM-9.0A 0 to 3 64S-16 3/8 in SM-9.0D 3 to 10 64H-16 3/8 in SM-9.0E Above 10 64E-22 3/8 in SM-9.5A 0 to 3 64S-16 3/8 in SM-9.5D 3 to 10 64H-16 3/8 in SM-9.5E Above 10 64E-22 3/8 in SM-12.5A 0 to 3 64S-16 1/2 in SM-12.5D 3 to 10 64H-16 1/2 in SM-12.5E Above 10 64E-22 1/2 in IM-19.0A Less than 10 64S-16 3/4 in IM-19.0D 10 to 20 64H-16 3/4 in IM-19.0E 20 and above 64E-22 3/4 in BM-25.0A All ranges 64S-16 1 in BM-25.0D Above 10 64H-16 1 in 1Minimum Asphalt Performance Grade (PG) is defined as the minimum binder performance grade for the job mixes as determined by AASHTO T170 or AASHTO M332. 2Aggregate Nominal Maximum Size is defined as one sieve size larger than the first sieve to retain more than 10 percent aggregate. Note: SM = Surface Mixture; IM = Intermediate Mixture; BM = Base Mixture Asphalt concrete shall conform to the requirements for the mix type designated on the plans or elsewhere in the Contract for use. At the Contractor’ s option, an approved Warm Mix Asphalt (WMA) additive or process may be used to produce the asphalt concrete (AC) mix type designated.
211.02 Materials
a.Asphalt materials shall conform to the requirements of Section 210 except asphalt cement materials shall be performance graded (PG) in accordance with AASHTO M332. In addition, asphalt mixtures with the E designation shall meet the asphalt cement requirements in Section 211.04(e)1.
b.Coarse aggregate shall be Grade A or B conforming to the requirements, except for grading, of Section 203 for quality. In addition, the coarse aggregate sizes retained on and above the No. 4 sieve shall comply with the coarse aggregate requirements in Table II-12A. Flat and elongated (F&E) particles shall be tested in accordance with ASTM D 4791, and coarse aggregate angular - ity (CAA) shall only be tested on crushed gravel in accordance with ASTM D 5821.
c.Fine aggregate shall conform to the requirements, except for grading, of Section 202 for quality and the fine aggregate requirements in Table II-12A. Fine aggregate angularity (FAA) shall be tested in accordance with AASHTO T 304 (Method A) and the sand equivalent (SE) shall be tested in accordance with AASHTO T 176.
d.After a gradation test is performed:211.02 166 1. If 10 percent or more of the material is retained on the No. 4 sieve, that portion shall be tested in accordance with the requirements for coarse aggregate.
2.If 10 percent or more of the material passes the No. 4 sieve, that portion shall be tested for SE.
3.If 10 percent or more of the material passes the No. 8 sieve, that portion shall be tested for FAA.
e.Fine or coarse aggregates that tend to polish under traffic will not be permitted in any final surface exposed to traffic except in areas where the two-way average daily traffic is less than 750 vehicles per day and as permitted elsewhere in these Specifications.
f.Mineral filler shall conform to the requirements of Section 201.
g.Aggregate for asphalt concrete shall be provided in sufficient sizes and amounts to produce a uniform mixture. The Contractor shall indicate on the proposed job-mix formula the separate approximate sizes of aggregate to be used. Where segregation or nonuniformity is evident in the finished pavement, the Engineer reserves the right to require the Contractor to discontinue the use of crusher run or aggregate blends and to furnish separate sizes of open-graded aggregate material. TABLE II-12A Standard Deviation Coarse Aggregate Properties CAA ASTM D4791 Fine Aggregate 1 fractured 2 fractured F & E “(5:1) Properties Mix Type face faces % by weight SE FAA SM-9.0 A 85% min. 80% min. 10% max.1 40% min. 40% min. SM-9.0 D 85% min. 80% min. 10% max.1 45% min. 45% min. SM-9.0 E 95% min. 90% min. 10% max.1 45% min. 45% min. SM-9.5 A 85% min. 80% min. 10% max.1 45% min. 45% min. SM-9.5 D 85% min. 80% min. 10% max.1 45% min. 45% min. SM-9.5 E 95% min. 90% min. 10% max.1 45% min. 45% min. SM-12.5 A 85% min. 80% min. 10% max.1 45% min. 45% min. SM-12.5 D 85% min. 80% min. 10% max.1 45% min. 45% min. SM-12.5 E 95% min. 90% min. 10% max.1 45% min. 45% min. IM-19.0 A 85% min. 80% min. 10% max.1 45% min. 45% min. IM-19.0 D 95% min. 90% min. 10% max.1 45% min. 45% min. IM-19.0 E 95% min. 90% min. 10% max.1 45% min. 45% min. BM-25.0 A 80% min. 75% min. 10% max.1 45% min. 45% min. BM-25.0 D 80% min. 75% min. 10% max.1 45% min. 45% min. 110 percent measured at 5:1 on maximum to minimum dimensions
h.An antistripping additive shall be used in all asphalt mixes. It may be hydrated lime or a chemical additive from the Materials Division Approved Products List No. 7 or a combination of both. The approved chemical additive shall be added at a rate of not less than 0.30 percent by weight of the total asphalt content of the mixture.211.02 167The mixture shall produce a tensile strength ratio (TSR) of not less than 0.80 for the design and production tests. The TSR shall be determined in accordance with AASHTO T283, including a freeze-thaw cycle (4-inch specimens compacted with a Marshall Hammer or 3.5 by 6-inch speci - mens when compacted with a gyratory compactor); except that the 16-hour curing time requirement and the 72 to 96-hour storage period will not be enforced.by the Department. Design tests shall use the same materials that are to be used in the production mix and shall be conducted in a laboratory approved by the Department. When a chemical additive is used, it shall be added to the asphalt cement prior to the introduction of the cement into the mix. Any chemical additive or particular concentration of chemical additive found to be harmful to the asphalt material or that changes the original asphalt binder performance grade (PG) shall not be used.
i.Hydrated lime shall conform to the requirements of ASTM C977. Hydrated lime shall be added at a rate of not less than 1 percent by weight of the total dry aggregate. A separate bin or tank and feeder system shall be provided to store and accurately proportion the dry or slurried lime into the aggregate. The lime and aggregate shall be mixed by pugmill or other Department approved means to achieve a uniform lime coating of the aggregate prior to entering the drier. If lime is added in dry form, the aggregate shall contain at least 3 percent free moisture. The Department will not permit the stockpiling of lime treated aggregate. The feeder system shall be controlled by a proportioning device, which shall be accurate to within ±10 percent of the specified amount. The proportioning device shall have a convenient and accurate means of calibration. A flow indicator or sensor shall be provided with the proportioning device and interlocked with the plant controls, aggregate feed or weigh system, such that production of the mixture shall be consistently maintained and, if there is a stoppage of the lime feed, interrupted. The method of introducing and mixing the lime and aggregate shall be subject to approval by the Engineer prior to beginning production.
j.Reclaimed Asphalt Pavement (RAP) material may be used as a component material of asphalt mixtures in conformance with the following:
1.Asphalt surface, intermediate and base mixtures containing RAP (but without RAS) should use the performance grade (PG) of asphalt cement as indicated in Table II-I4A, however, the choice of PG to use in the mix shall be the responsibility of the Contractor in order to meet the require - ments of Section 211.01
2.The final asphalt mixture shall conform to the requirements for the type specified.
3.During the production process, RAP material shall not be allowed to contact open flame.
4.RAP material shall be handled, hauled, and stored in a manner that will minimize contamination. Further, the material shall be stockpiled and used in such manner that variable asphalt contents and asphalt penetration values will not adversely affect the consistency of the mixture.
5.RAP shall be processed in such a manner as to ensure that the maximum top size particle of material introduced into the mix shall be 2 inches. The Engineer may require smaller sized particles to be introduced into the mix if the reclaimed particles are not broken down or uniformly distributed throughout the mixture during heating and mixing.211.02 168(k) Reclaimed Asphalt Shingles (RAS) – Tear-off RAS Material s in Asphalt Concrete
1.Asphalt surface, intermediate, and base mixtures containing Tear-off RAS Materials shall meet the requirements of Section 211.01 and 211.03.
2.Tear-off RAS Materials shall be discarded shingle scrap from the re-roofing of domestic build- ings. These tear-offs shall have been produced by the manufacturing process for roofing shingles. Tear-off RAS materials shall contain less than 3.0 percent foreign materials such as paper, roofing nails, wood, or metal flashing. Materials shall be shredded prior to being incorporated in the AC mixture so that at least 99 percent of the shredded pieces pass the 1/2 inch (12.5 mm) sieve and at least 80 percent pass the #4 (4.75 mm) sieve. Tear-off RAS materials shall not have asbestos containing material (ACM) as defined by the National Emission Standards for Hazardous Air Pollutants (NESHAP), which is less than 1 percent asbestos. The Contractor shall furnish a certification obtained from the recycler that Polarized Light Microscopy (PLM) tests were performed on random samples of RAS at the rate of 1 test per 100 tons or if operating under a Virginia DEQ permit the rate will be the 1 test per 750 tons. The test results shall reveal no detectable level of ACM. Copies of the test results from the recycler shall be available upon request.
3.Asphalt Binder of the asphalt concrete mixture shall be Performance Grade (PG) of asphalt conforming to the requirements specified in Section 211.
4.RAS tear-offs in asphalt concrete shall be mixed mechanically in a plant specifically designed for asphalt concrete production.
5.Contractors shall store tear-off RAS materials by stockpiling either whole or as partial shingles which have not been shredded or shredded shingles that meet the maximum size requirements. Stockpiled RAS shall not be contaminated by dirt or other objectionable foreign materials. Blending of the shingles with fine aggregate may be necessary to prevent conglomeration of shingle particles. When fine aggregate is used for this purpose, this material shall be accounted for in the mix design.
l.Reclaimed Asphalt Shingles (RAS) – Tabs RAS Materials in Asphalt Concrete
1.Asphalt surface, intermediate, and base mixtures containing Tabs RAS Materials shall meet the requirements of Section 211.01 and 211.03.
2.Tabs RAS Materials shall be produced by the manufacturing process for domestic roofing shingles. Blending or mixing of Tabs and Tear-offs shall not be permitted. Tabs RAS Materials shall be shredded prior to being incorporated into the asphalt concrete mixture so that one hundred percent of the shredded pieces are less than 1/2 inches (12.5mm) in any dimension. Tabs RAS Materials shall not contain asbestos fibers. The Contractor shall furnish the Depart - ment a certification from the manufacturer of the shingles stating that the shingles are free of asbestos. If a certification cannot be obtained then the Contractor shall furnish test results of RAS sample analysis for Polarized Light Microscopy (PLM) on the shingles which certify the 211.02 169material to be used is free of asbestos. Testing is required at the specified rate of 1 per manu - facturer per type of RAS prior to processing and results shall be submitted prior to or during the stockpile approval process.
3.Asphalt Binder of the asphalt concrete mixture shall be Performance Grade (PG) of asphalt conforming to the requirements specified in Section 211.
4.Tabs RAS Materials in asphalt concrete shall be mixed mechanically in a plant specifically designed for asphalt concrete production.
5.Contractors shall store Tabs RAS materials by stockpiling either whole or as partial shingles which have not been shredded or shredded shingles that meet the maximum size requirements. Stockpiled RAS shall not be contaminated by dirt or other objectionable foreign materials. Blending of the shingles with fine aggregate may be necessary to prevent conglomeration of shingle particles. When fine aggregate is used for this purpose, this material shall be accounted for in the mix design.
m.Warm Mix Asphalt (WMA) additives or processes shall be approved by the Department prior to use and shall be obtained from the Department’ s approved list which is included in the Materials Division’ s Manual of Instructions.
211.03 Job-Mix Formula
The Contractor shall submit a job-mix formula for each mixture planned for use on the project for the Department’ s evaluation and approval through the “Producer Lab Analysis and Information Details” (PLAID) website. Paper copies of the job mix formula along with supporting documentation shall also be submitted to the Department. The job-mix formula shall be within the design range specified. The job-mix formula shall establish a single percentage of aggregate passing each required sieve, a single percentage of asphalt material to be added to the aggregate, a temperature at which the mixture is to be produced, and a temperature at which the mixture is to be compacted for SUPERPA VE testing in accor - dance with AASHTO R35. Each approved job-mix formula shall remain in effect provided the results of tests performed on material currently being produced consistently comply with the requirements of the job-mix formula for grading, asphalt content, temperature, and SUPERPA VE compaction results and the requirements of Section 315.
a.SUPERPA VE mixes shall be designed and controlled in accordance with AASHTO R35 and as specified herein. The Contractor shall have available all of the equipment outlined in AASHTO T312 (Section 4-6) and a Department-certified Asphalt Mix Design Technician. The SUPERPA VE mixture shall be compacted in a gyratory compactor with an internal angle of 1.16 + 0.02 degrees. The internal angle shall be measured and calibrated using a cold (non-mix) device . The SUPERPA VE Gyratory Compactor (SGC) shall be one from the Department’ s approved list of devices found in the Materials Division’ s Manual of Instructions. The SUPERPA VE mixes shall conform to the requirements of Table II-13 and Table II-14. Section 7.1.2 of AASHTO R30 shall be modified such that the compaction temperature is as specified in (d) 6 herein.
b.In conjunction with the submittal of a job-mix formula, the Contractor shall submit complete SUPERPA VE design test data, ignition furnace calibration data in accordance with VTM-102 prepared by an approved testing laboratory, and viscosity data or supplier temperature recommen - dations for the asphalt cement if different from (d) 6 herein.211.03 170(c) Three trial blends for gradation shall be run at one asphalt content.
d.The SUPERPAVE design test data shall include, but not be limited to, the following information:
1.Grading data for each aggregate component of three trial blends shall be submitted to the Department. The data for the mixture shall show percent passing for the following sieves: 2 inch, 1 1/2 inch, 1 inch, 3/4 inch, 1/2 inch, 3/8 inch, No. 4, No. 8, No. 16, No. 30, No. 50, No. 100, and No. 200. The grading shall be reported to the nearest 1.0 percent except the No. 200 sieve shall be reported to the nearest 0.1 percent.
2.The test data shall include, but not be limited to, the percentage of each aggregate component as compared to the total aggregate in the asphalt mixture. The specific gravity and aggregate properties for coarse and fine aggregates defined in Section 211.02 (b) and (c), including flat and elongated properties, for each aggregate component or for the total aggregates used in the mixture shall be reported. Aggregate properties, except sand equivalent, shall be reported for RAP portions of a mixture. The aggregate specific gravity of RAP shall be the effective aggregate specific gravity calculated from the results of tests conducted in accordance with AASHTO T 209 and VTM-102. TABLE II-13 Asphalt Concrete Mixtures: Design Range Percentage by Weight Passing Square Mesh Sieves Mix Type 2 1 1/2 1 3/4 1/2 3/8 No. No. No. No. No. in. in. in. in. in. in. 4 8 30 50 200 SM-9.0 1001 90-100 90 max. 47-67 2-10 A,D,E SM-9.5 1001 90-100 58-80 38-67 23 max 2-10 A,D,E SM-12.5 100 95-100 90 max. 58-80 34-50 23 max 2-10 A,D,E IM-19.0 100 90-100 90 max. -- -- 28-49 2-8 A,D,E BM-25.0 100 90-100 90 max. -- -- -- 19-38 1-7 A,D C 100 92-100 70-75 50-60 28-36 15-20 7-9 (Curb Mix) 1A production tolerance of 1% will be applied to this sieve regardless of the number of tests in the lot.211.03 171TABLE II-14 Mix Design Criteria VFA VFA VFA Min. Fines/Asphalt No. of Mix Type (%) (%) (%) VMA Ratio Gyrations Production Design Production % N Design SM-9.0A 1,2 2.0-5.0 75-80 70-85 17 0.6-1.3 50 SM-9.0D 1,2 2.0-5.0 75-80 70-85 17 0.6-1.3 50 SM-9.0E 1,2 2.0-5.0 75-80 70-85 17 0.6-1.3 50 SM-9.5A 1,2 2.0-5.0 75-80 70-85 16 0.7-1.3 50 SM-9.5D 1,2 2.0-5.0 75-80 70-85 16 0.7-1.3 50 SM-9.5E 1,2 2.0-5.0 75-80 70-85 16 0.7-1.3 50 SM-12.5A 1,2 2.0-5.0 73-79 68-84 15 0.7-1.3 50 SM-12.5D 1,2 2.0-5.0 73-79 68-84 15 0.7-1.3 50 SM-12.5E 1,2 2.0-5.0 73-79 68-84 15 0.7-1.3 50 IM-19.0A 1,2 2.0-5.0 69-76 64-83 14 0.6-1.3 50 IM-19.0D 1,2 2.0-5.0 69-76 64-83 14 0.6-1.3 50 IM-19.0E 1,2 2.0-5.0 69-76 64-83 14 0.6-1.3 50 BM-25.0A 2,3 1.0-4.0 67-87 67-92 13 0.6-1.3 50 BM-25.0D 2,3 1.0-4.0 67-87 67-92 13 0.6-1.3 50 1Asphalt content should be selected at 4.0% air voids for A & D mixes, 3.5% air voids for E mix. 2Fines-asphalt ratio is based on effective asphalt content. 3Base mix shall be designed at 2.5% air voids. BM-25A shall have a minimum asphalt content of 4.4% unless otherwise approved by the Engineer. BM-25D shall have a minimum asphalt content of 4.6% unless otherwise approved by the Engineer.
3.The aggregate grading in the asphalt mixture shall be determined by igniting or extracting the asphalt from a laboratory-prepared sample. The laboratory sample shall be batched on the basis of component percentages as indicated in (d) 2. herein and at the proposed job-mix asphalt content. The aggregate shall be obtained in accordance with VTM-102 or VTM-36, when approved. Sieves specified in (d) 1. herein shall be reported, beginning with the top size for the mix.
4.The following volumetric properties of the compacted mixture, calculated on the basis of the mixture’ s maximum specific gravity determined in accordance with AASHTO T -209, shall be reported to the Engineer. The mixture shall be aged in accordance with AASHTO R30 and the bulk specific gravity of the specimens determined in accordance with AASHTO T -166, Method A, for each asphalt content tested. Properties shall be determined and reported in accordance with AASHTO R35
a.V oids in total mix (VTM)
b.V oids in mineral aggregate (VMA)
c.V oids filled with Asphalt (VFA)
d.Fines/Asphalt ratio (F/A ) 211.03 172 5. The value of the maximum specific gravity of the asphalt mixture used in (c) 4. herein shall be reported to three decimal places.
6.The mixing and compaction temperature for testing shall be as follows:
a.For mixes designation A, the mix temperature shall be 300 degrees F to 310 degrees F and the compaction temperature shall be 285 degrees F to 290 degrees F .
b.For mixes designation D, the mix temperature shall be 310 degrees F to 320 degrees F and the compaction temperature shall be 295 degrees F to 300 degrees F .
c.In cases involving PG 64E-22 or modified binders, the temperatures shall be based on documented supplier’ s recommendations.
7.The field correction factor as determined by subtracting the bulk specific gravity of the aggregate from the effective specific gravity of the aggregate at the design asphalt content.
8.For surface mixes, permeability test data shall be submitted in accordance with VTM 120 using either single point verification or the regression method for each surface mix having a different gradation. If the average of the permeability results from the single point verification method exceeds 150 x 10-5 cm/sec, or if the regression method predicts a permeability exceeding 150 x 10-5 cm/sec at 7.5% voids, the Contractor shall redesign the mixture to produce a permeability number less than 150 x 10-5 cm/sec.
e.The SUPERPA VE design binder content test data shall be plotted on graphs as described in AASHTO R 35 and shall show that the proposed job-mix formula conforms to the requirements of the designated mix type.
f.A determination will be made to verify if any asphalt concrete mixture being produced conforms to the job-mix formula approved by the Department. The Department and Contractor will test the mix - ture using samples removed from production. The following tests will be conducted to determine the properties listed: Property Test Asphalt content VTM-102, (VTM-36 when approved) Gradation AASHTO T -30 SUPERPA VE properties AASHTO R35 Asphalt cement material AASHTO T316 or T -201 For Warm Mix Asphalt (WMA), SUPERPA VE properties for mixing and compaction temperatures will be determined by the Department and Contractor based on the mix designations in Section 211.03(d)6. The Department will perform rut testing in accordance with the procedures detailed in VTM-110. If the results of the rut testing do not conform to the following requirements, the Engineer reserves the right to require adjustments to the job-mix formula: Mix Designation Maximum Rut Depth, mm A 7.0 D 5.5 E, (S) 3.5211.03 173TABLE II-14A Recommended Performance Grade of Asphalt Cement Percentage of Reclaimed Asphalt Pavement (RAP) in Mix Mix Type %RAP /H11349 25.0% /H11021 %RAP /H11349 25.0% /H11021 %RAP /H11349 25.0% 30.0% 35.0% SM-4.75A, SM-9.0A, PG 64S-22 PG 64S-22 SM-9.5A, SM-12.5A SM-4.75D, SM-9.0D, PG 64H-22 PG 64S-22 SM-9.5D, SM-12.5D IM-19.0A PG 64S-22 PG 64S-22 IM-19.0D PG 64H-22 PG 64S-22 BM-25.0A PG 64S-22 PG 64S-22 BM-25. 0D PG 64H-22 PG 64S-22 After calibration of the gyratory compactor is completed, the Engineer may require the Contractor to make adjustments to the job-mix formula. If the Department determines that the mixture being produced does not conform to the approved job-mix formula and volumetric properties specified in Table II-14 based on the Department’ s or Contractor’ s test results, the Contractor shall immediately make corrections to bring the mixture into conformance with the approved job-mix formula or cease paving with that mixture. Subsequent paving operations using either a revised or another job-mix formula that has not been verified as described herein shall be limited to a test run of 100 to 300 tons of mixture if such ma - terial is to be placed in Department project work. No further paving for the Department using that specific mixture shall occur until the acceptability of the mixture being produced has been verified using the 100 to 300 ton constraint. Based on rut testing performed by the Department and/or field performance of the job mix, the Engineer reserves the right to require the Contractor to make adjustments to the job-mix formula.
g.When using RAS Materials (Tear-off or Tabs) , the Contractor shall submit material samples to include the RAS stockpiled tear-off shingles, reclaimed asphalt pavement (RAP) and PG Binder. The amount of RAS material used in the recycled mixture shall be no more than five percent of the total mixture weight. However, the combined percentages of RAS and RAP shall not contribute more than 30 percent (by weight) of the total asphalt content of the mixture, according to the fol - lowing equation:211.03 (%RAS mix /H11003 %AC RAS/100) + (%RAP mix /H11003 %AC RAP/100) %AC JMF/H11349 30.0% 174Where: % RAS mix = Percent RAS in the Job Mix Formula % AC RAS = Average Percent AC in the RAS % RAP mix = Percent RAP in the Job Mix Formula % AC RAP = Average Percent AC in the RAP % AC JMF = Design AC content of the JMF The Contractor shall determine the asphalt content of the RAS using AASHTO T-164, Method B, or VTM-102 and report the average results to the nearest 0.1 percent. When the ignition furnace is used, a correction factor shall be applied for the non-asphalt combustible materials in the RAS. Unless the actual correction factor is determined by comparing the test results on paired samples from AASHTO T-164 Method B and VTM-102, the estimated correction factor for the RAS shall be 5 percent. Used separately or with RAP , RAS can be used to stiffen the asphalt concrete mixture binder to meet the requirements in Section 211. Asphalt surface, intermediate, and base mixtures containing RAS in order to meet the asphalt concrete mixture stiffness of PG 64H-16 should use PG 64S-22 asphalt cement. Further, mixes using RAS shall not exceed the 30 percent (by weight) and are required to use the maximum binder replacement criteria noted here: • 5% RAS and 0% RAP • 4% RAS and 5% RAP minimum • 3% RAS and 10% RAP minimum • 2% RAS and 20% RAP minimum Interpolation shall be used to determine combinations between the whole number RAS/RAP usage figures shown herein, subject to review and approval by the Engineer.
211.04 Asphalt Concrete Mixtures
Asphalt concrete mixtures shall conform to the requirements of Table II-14 and the following:
a.Types SM-9 .0A, SM-9 .0D, SM-9 .0E, SM-9 .5A, SM-9 .5D, SM-9 .5E, SM-12 .5A, SM-12 .5D, and SM-12 .5E asphalt concrete shall consist of crushed stone, crushed slag, or crushed gravel and fine aggregate, slag or stone screenings, or a combination thereof combined with asphalt cement. NOTE: For all surface mixes, except where otherwise noted, no more than 5 percent of the aggregate retained on the No. 4 sieve and no more than 20 percent of the total aggregate may be polish susceptible. At the discretion of the Engineer, SM-9.5AL or SM-12.5AL may be specified and polish susceptible aggregates may be used (without percentage limits). NOTE: Unless Type C (curb mix) is specified by the Engineer in the Contract, SM9.0, SM-9.5, and SM-12.5 mix types are acceptable for use in the construction of asphalt curbing.
b.Types IM-19 .0A, IM-19 .0D, and IM-19 .0E asphalt concrete shall consist of crushed stone, crushed slag, or crushed gravel and fine aggregate, slag or stone screenings, or a combination thereof combined with asphalt cement.211.03 175NOTE: At the discretion of the Engineer, an intermediate mix may be designated as either SM-19.0A, SM-19.0D or SM-19.0E. When designated as such, no more than 5 percent of the aggregate retained on the No. 4 sieve may be polish susceptible. All material passing the No. 4 sieve may be polish susceptible.
c.Types BM-25 .0A and BM-25 .0D asphalt concrete shall consist of crushed stone, crushed slag, or crushed gravel and fine aggregate, slag or stone screenings, or a combination thereof combined with asphalt cement.
d.Type C (curb mix) asphalt concrete shall consist of a blend of No. 78 or No. 8 crushed aggregate, No. 10 crushed aggregate, fine aggregate, mineral filler, and a stabilizing additive from the Depart - ment’ s approved list found in the Materials Division’ s Manual of Instructions combined with 6.0 to 9.0 percent of PG 64S-22. This mix does not require a volumetric mix design or volumetric testing under the SUPERPA VE system.
e.Type SM-9 .5, SM-12 .5, IM-19 .0 and BM-25 .0 asphalt concrete may be designated E (polymer modified), or stabilized (S). Asphalt concrete mixtures with the E designation may not be stabilized.
1.Type E asphalt mixtures shall consist of mixes incorporating a neat asphalt material with polymer modification complying with the requirements of PG 64E-22 and have a rolling thin film oven test residue elastic recovery at 77 degrees F of a minimum of 70 percent when tested in accordance with ASTM D 6084 procedure A. E designated mixtures shall not contain more than 15 percent reclaimed asphalt pavement (RAP) material (by weight) or 3 percent recycled asphalt shingles (RAS) (by weight).
2.Type E (HP) asphalt mixtures shall consist of mixes incorporating a neat asphalt material with a high polymer modification (approximately 7.5%) complying with AASHTO M332 for PG 76E-28(HP) with the exception that Multiple Stress Creep and Recovery (MSCR) shall have a Jnr3.2 maximum value of 0.1 kPa-1 when tested according to AASHTO T350. The minimum MSCR % recovery at 3.2 kPa shall be 90%. The MSCR test for Jnr and % recovery shall be run at 76°C. The viscosity shall be less than or equal to 3.0 Pa-s, however the Engineer may increase this limit to 5.0 Pa-s if the binder supplier and contractor agree that the binder is suitably workable. HP designated mixtures shall not contain more than 15% RAP material.
3.Type (S) asphalt mixtures shall consist of mixes incorporating a stabilizing additive from the Department’ s approved list found in the Materials Division’ s Manual of Instructions. These mixes shall be designated with an (S) following the standard mix designation. The minimum required additive shall be as specified on the Department’ s approved list found in the Materials Division’ s Manual of Instructions.
4.Type L asphalt mixtures will be allowed to contain a 100 percent polishing course and fine aggregate. These mixes shall be designated with a L following the standard mix designation.
211.05 Testing
The Contractor shall provide the quality control and quality assurance necessary for the Department to determine conformance with the required grading, asphalt content, and temperature properties for asphalt concrete. The Contractor shall have a Department-certified Asphalt Mix Design Technician for designing and adjusting mixes as necessary. The Asphalt Mix Design Technician or Asphalt Plant Level II Technician may perform testing of asphalt mixes. The Asphalt Mix Design Technician shall be responsible for 211.05 176reviewing and approving the results of all testing. The Asphalt Mix Design Technician shall be available and have direct communication with the plant for making necessary adjustments in the asphalt concrete mixes at the mixing plant. The Asphalt Mix Design Technician and Asphalt Plant Level II Technician shall each be capable of conducting any tests necessary to put the plant into operation; however, the Asphalt Mix Design Technician shall be responsible for producing a mixture that complies with the requirements of these Specifications. The Department will award certification. The Contractor shall maintain all records and test results associated with the material production and shall maintain appropriate current quality control charts. Test results and control charts shall be available for review by the Engineer. The Contractor shall execute a quality control plan of process inspections and tests, including the deter - mination of SUPERPA VE properties. The results of the SUPERPA VE tests shall be used, along with the results of other quality control efforts, to achieve and maintain the quality of the mixture being produced. The Contractor shall perform at least one field SUPERPA VE test per day per mix or per 1,000 tons per mix if more than 1,000 tons of a mix is produced per day. Aging as described in AASHTO R30 shall not be performed. If less than 300 tons of asphalt mixture is produced under a single job-mix formula in a day, field SUPERPA VE testing will not be required on that day. That day’ s tonnage shall be added to subsequent production. When the accumulated tonnage exceeds 300 tons, minimum testing frequency shall apply. Field SUPERPA VE test results shall be plotted and displayed in control chart form in the plant immediately following the completion of each individual test. The tests shall determine asphalt content in percentages to the nearest 0.01. The tests shall determine VTM, VMA, VFA, and F/A in percentages to the nearest 0.1 percent. The Department will conduct on-site inspections so the Contrac - tor’ s Asphalt Mix Design Technician can demonstrate knowledge of the SUPERPA VE mix design and production requirements on Department-supplied mixtures. Aggregate specific gravity and aggregate property tests shall be conducted by a Department-certified Aggregate Properties Technician or Asphalt Mix Design Technician on each aggregate component (including RAP) or total aggregate mixture once at mix design stage and once prior to beginning produc - tion in each calendar year. Sand equivalent shall not be determined on RAP . In addition, for each 50,000 tons of each aggregate size used at each plant, aggregate specific gravity and the results of aggregate property tests shall be reported for each aggregate component or the total aggregate mixture. Otherwise, if the total blend (cold feed) is used to determine aggregate specific gravity and aggregate properties, these tests shall be run for each 50,000 tons of the total blend. Field SUPERPA VE tests shall be performed to N design gyrations as specified in Table II-14.
211.06 Tests
The Department may sample materials entering into the composition of the asphalt concrete, the mixture, or the completed pavement. The Contractor shall cooperate with the Engineer in obtaining these samples. When samples are obtained from the pavement by coring, the resulting voids shall be filled and refinished by the Contractor without additional compensation. Abson recovery samples shall be PG graded according to the requirements of AASHTO M 322-14. Samples meeting the required grades specified in Section 211.01 shall be acceptable. When the Department performs PG grading on the asphalt in a Contractor’ s liquid asphalt storage tank, the Engineer will notify the asphalt concrete producer and binder supplier if tests indicate that the binder 211.05 177properties of the asphalt material differ from those of the approved job-mix. The asphalt concrete producer and binder supplier shall determine what corrective action must be taken with the approval of the Engineer.
211.07 Plant Inspection
The Department will accept the preparation of asphalt concrete mixtures under a quality assurance plan. The Contractor shall provide a laboratory as specified in Section 106.07. In addition, the Contractor shall have all laboratory scales and gyratory compactors calibrated once a year by an independent source. The Contractor shall maintain the calibration records for 3 years from the date of the last calibration.
211.08 Acceptance
Acceptance will be made under the Department’ s quality assurance program, which includes the testing of production samples by the Contractor and of monitor samples by the Department. Sampling and test - ing for the determination of grading, asphalt cement content, and temperature shall be performed by the Contractor, and the Department will perform independent monitor checks at a laboratory of its choosing. The Contractor shall input such test results within 24 hours of sampling to the Department through the “Producer Lab Analysis and Information Details” (PLAID) website https://plaid.vdot.virginia.gov, unless otherwise approved by the appropriate District Materials Engineer. Where the Contractor’ s test results indicate that the mixture conforms to the gradation, asphalt cement content, and mix temperature requirements of the Specifications, the mixture will be acceptable for these properties; however, nothing herein shall be construed as waiving the requirements of Section 106.06, Section 200.02, Section 200.03, and Section 315 or relieving the Contractor of the contractual obligation to furnish and install a finished functional product that conforms to the requirements of the Contract. If a statistical comparative analysis of the Contractor’ s test results and the Department’ s monitor tests indicate a statistically significant dif - ference in the results and either of the results indicates that the material does not conform to the grading and asphalt cement content requirements of the Specifications, the Department and the Contractor will make an investigation to determine the reason for the difference. If it is determined from the investigation that the material does not conform to the requirements of the Contract, price adjustments will be made in accordance with Section 211.09. Acceptance for gradation and asphalt cement content will be based on the mean of results of eight tests performed on samples taken in a stratified random manner from each 4,000-ton lot (8,000-ton lots may be used when the normal daily production of the source from which the material is being obtained is in excess of 4,000 tons). The Contractor shall take samples from the approximate center of the truckload of material unless otherwise approved by the Engineer. Any statistically acceptable method of randomiza - tion may be used to determine when to take the stratified random sample; however, the Department shall be advised of the method to be used prior to the beginning of production. A lot will be considered to be acceptable for gradation and asphalt content if the mean of the test results obtained is within the tolerance allowed for the job-mix formula as specified in Table II-15. The temperature of the mixture at the plant shall be controlled to provide load-to-load uniformity during changing weather conditions and surface temperatures. The maximum temperature of mix designations A and D and base mixes shall not exceed 350 degrees F unless otherwise directed by the Engineer. The max - imum temperature as recommended by the supplier shall not be exceeded for a mix designated E or (S).211.08 178If the job-mix formula is modified within a lot, the mean test results of the samples taken will be compared to the applicable process tolerance shown in Table II-15. Asphalt content will be measured as extractable asphalt or weight after ignition. The Contractor shall submit a copy of burn tickets from an ignition oven to the Engineer and all the original tickets shall be available upon Engineer’ s request. Original tickets shall be maintained on file by the Contractor for a period of 5 years or until final acceptance of the applicable contract, whichever is greater. TABLE II-15 Process Tolerance Tolerance on Each Laboratory Sieve and Asphalt Content: Percent Plus and Minus No. Top No. No. No. No. No. Tests Size1 1 1/2” 1” 3/4” 1/2” 3/8” 4 8 30 50 200 A.C. 1 0.0 8.0 8.0 8.0 8.0 8.0 8.0 8.0 6.0 5.0 2.0 .60 2 0.0 5.7 5.7 5.7 5.7 5.7 5.7 5.7 4.3 3.6 1.4 0.43 3 0.0 4.4 4.4 4.4 4.4 4.4 4.4 4.4 3.3 2.8 1.1 0.33 4 0.0 4.0 4.0 4.0 4.0 4.0 4.0 4.0 3.0 2.5 1.0 0.30 5 0.0 3.6 3.6 3.6 3.6 3.6 3.6 3.6 2.7 2.2 0.9 0.27 6 0.0 3.3 3.3 3.3 3.3 3.3 3.3 3.3 2.4 2.0 0.8 0.24 7 0.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 2.3 1.9 0.8 0.23 8 0.0 2.8 2.8 2.8 2.8 2.8 2.8 2.8 2.1 1.8 0.7 0.21 12 0.0 2.3 2.3 2.3 2.3 2.3 2.3 2.3 1.7 1.4 0.6 0.17 1Defined as the sieve that has 100% passing as defined in Table II-13. Field SUPERPA VE tests will be performed by the Department in accordance with AASHTO R35 during the production of the approved job mixes designed by the SUPERPA VE method. Aging, as described in AASHTO R30, will not be performed. Should any field SUPERPA VE test fail with regard to the limits specified in Table II-14, the Department may require that production be stopped until necessary correc - tive action is taken by the Contractor. The Engineer will investigate and determine the acceptability of material placed and represented by failing field SUPERPA VE test results. Should visual examination by the Engineer reveal that the material in any load or portion of the paved roadway is obviously contaminated or segregated, that load or portion of the paved roadway will be rejected without additional sampling or testing of the lot. If it is necessary to determine the gradation or asphalt content of the material in any load or portion of the paved roadway, samples will be taken and tested and the results will be compared to the requirements of the approved job-mix formula. The results obtained in the testing will apply only to the material in question.
211.09 Adjustment System
If a lot of material does not conform to the acceptance requirements of Section 211.08, the Department will determine adjustment points as follows:211.08 179Adjustment Points for Each 1% the Gradation Is Outside the Process Tolerance Permitted In Table II-15 Sieve Size (Applied in 0 .1% increments) 1 1/2 in 1 1 in 1 3/4 in 1 1/2 in 1 3/8 in 1 No. 4 1 No. 8 1 No. 30 2 No. 50 2 No. 200 3 TABLE II-16 Standard Deviation Standard Deviation 2 Adjustment Points 3 Adjustment Points Sieve Size 1 Adjustment Point for for Each Sieve Size for Each Sieve Size and A .C. Each Sieve Size and A .C. and A .C. and A .C. 1/2 in. 3.8-4.7 4.8-5.7 5.8-6.7 3/8 in. 3.8-4.7 4.8-5.7 5.8-6.7 No. 4 3.8-4.7 4.8-5.7 5.8-6.7 No. 8 3.0-3.9 4.0-4.9 5.0-5.9 No. 30 2.2-3.1 3.2-4.1 4.2-5.1 No. 50 1.5-2.4 2.5-3.4 3.5-4.4 No. 200 1.1-2.0 2.1-3.0 3.1-4.0
A.C. 0.27-0.36 0.37-0.46 0.47-0.56 One adjustment point will be applied for each 0.1 percent that the material is out of the process tolerance for asphalt content. If the total adjustment for a lot is greater than 25 points, the Contractor shall remove the failing material from the road. If the total adjustment is 25 points or less and the Contractor does not elect to remove and replace the material, the unit price for the material will be reduced 1 percent of the unit price bid for each adjustment point the material is outside of the process tolerance. The Engineer will apply this adjustment to the tonnage represented by the sample(s). If the Engineer applies adjustment points against two successive lots, the Contractor shall ensure plant adjustment is made prior to continuing production. The Contractor shall control the variability of the Contractor’ s product in order to furnish a consistently uniform mix. When the quantity of any one type of material furnished to a project exceeds 4,000 tons, the variability of the total quantity furnished will be determined on the basis of the standard deviation for each sieve size and the asphalt content. If the standard deviation is within the ranges specified in Table II-16, the Engineer will adjust the unit bid price for the material as indicated herein. The Engineer will not make adjustments for standard deviation computations on more than two job mixes for the same type of material. The Engineer will reduce the unit bid price by 0.5 percent for each adjustment point applied for standard deviation.211.09 180211.10—Referee System
a.If the test results obtained from one of the eight samples taken to evaluate a particular lot appear to be questionable, the Contractor may request in writing that the results of the questionable sample be disregarded, whereupon the Contractor shall have either an AASHTO-accredited lab or a De - partment lab perform tests on five additional samples taken from randomly selected locations in the roadway where the lot was placed. If the Engineer determines that one of the 8 test results appears to be questionable, the Department will perform tests on five additional samples taken from the randomly selected locations in the roadway where the lot was placed. The test results of the seven original, i.e. unquestioned, samples will be averaged with the test results of the five road samples, and the mean of the test values obtained for the twelve samples will be compared to the requirements for the mean of twelve tests as specified in Table II-15.
b.If the Contractor questions the mean of the eight original test results obtained for a particular lot, the Contractor may request in writing approval to have either an AASHTO-accredited lab or a Department lab perform additional testing of that lot. If the Engineer determines that the mean of the eight original test results are questionable, the Department will perform additional testing of that lot. The test results of the eight samples will be averaged with the test results of four additional samples taken from randomly selected locations in the roadway where the lot was placed, and the mean of the test values obtained from the twelve samples will be compare to the requirements for the mean of twelve tests as specified in Table II-15. If the Contractor requests additional tests, as described in (a) or (b) herein, the Contractor shall sample the material and have either an AASHTO-accredited lab or Department lab test the material in accordance with Department-approved procedures. The Engineer may observe the sampling and testing. If the mean of the test values obtained for the twelve samples conforms to the requirements for the mean of twelve tests, the material will be considered acceptable. If the mean of the test values obtained for the twelve samples does not conform to the requirements for the mean result of twelve tests, the lot will be adjusted in accordance with the adjustment rate specified in Section 211.09. Samples of the size shown herein shall be saw cut by the Contractor for testing without the use of liquids: Application Rate Minimum Sample Size 125 lb/yd2 8 by 8 in 150 lb/yd2 7 by 7 in 200 lb/yd2 6 by 6 in 300 lb/yd2 5 by 5 in
211.11 Handling and Storing Aggregates
Aggregates shall be handled, hauled, and stored in a manner that will minimize segregation and avoid contamination. Aggregates shall be stockpiled in the vicinity of the plant and on ground that is denuded of vegetation, hard, well drained, or otherwise prepared to protect the aggregate from contamination. 211.10 181Placing aggregate directly from the crusher bins into the cold feed may be permitted provided the material is consistent in gradation. When different size aggregates are stockpiled, the stockpiles shall be separated to prevent commingling of the aggregates.
211.12 Asphalt Concrete Mixing Plant
Plants used for the preparation of asphalt concrete mixtures shall conform to the following requirements:
a.Certification for Plant Operation and Sampling: A Certified Asphalt Plant Level I Technician or a Certified Asphalt Plant Level II Technician shall sample material at the plant.
b.Plant Scales: Scales shall be approved in accordance with Section 109.01.
c.Drier: The plant shall include a drier(s) that continuously agitates the aggregate during the heating and drying process. The aggregate shall be dried to a point at which the moisture content of the completed mixture does not exceed 1 percent as determined from samples taken at the point of discharge from the mixing operation.
d.Feeder for Drier: The plant shall be equipped with accurate mechanical means for uniformly feeding the aggregate into the drier so that a consistent production and temperature are reached and maintained. Where different size aggregates are required to comply with grading specifications, they shall be proportioned by feeding into the cold elevator through a multiple compartment feeder bin, one bin for each size used, equipped with positive action gates that can be securely locked to maintain desired proportioning.
e.Bins: When bins are used, adequate and convenient facilities shall be provided to make possible the sampling of representative aggregate material from each bin. Each compartment shall be provided with an overflow pipe of such size and location to prevent contamination of the aggregate in adjacent compartments. Bins shall be provided with individual outlet gates that, when closed, will allow no leakage.
f.Thermometric Equipment: The plant shall be equipped with a thermometric instrument so placed at the discharge chute of the drier as to register automatically or indicate the temperature of the heated aggregate or the completed mix if a drier drum mixing plant is used. A thermometric device shall be fixed in the asphalt feed line at a suitable location near the charging valve at the mixer unit. Thermometric devices shall be maintained in good working condition and shall be subject to check - ing against the laboratory thermometer. Any thermometric devices that do not operate or accurately register temperatures shall be removed and repaired or replaced.
g.Pollution Control: Pollution control shall conform to the requirements of Section 107.16.
h.Equipment for Preparation of Asphalt Material: Tanks for the storage of asphalt material shall be equipped with a heating system capable of heating and holding the material at the required tem - peratures. A separate storage tank or a storage tank having separate compartments shall be available for each grade of asphalt cement being used on the project. The heating system shall be designed to heat the contents of the tank by means of steam, electricity, or other approved means so that no flame is in direct contact with the heating surface of the tank. The circulating system for the asphalt ma -211.12 182terial shall be designed to assure proper and continuous circulation during the operating period and to minimize oxidation. Pipelines shall be steam jacketed or insulated to prevent undue loss of heat. Storage facilities for asphalt material shall be sufficient capacity for at least one day’ s operation or an equivalent means of supply shall be provided that will ensure continuous operation. Provisions shall be made for measuring and sampling asphalt within storage tanks. When asphalt material is proportioned by volume, the temperature of the asphalt material in storage shall be uniformly maintained at ±20 degrees F during operation of the plant by means of an automatic temperature control device. A sampling valve shall be provided for sampling of each asphalt storage tank used in production of the mix. If there are multiple storage tanks, a dedicated valve for each tank shall be provided.
i.Asphalt Control: Asphalt material shall be accurately proportioned by volume or weight. When volumetric methods are used, measurements shall be made by means of meters or pumps, calibrated for accuracy. The section of the asphalt line between the charging valve and the spray bar shall be provided with an outlet valve for checking the meter. When proportioned by weight, the asphalt material shall be weighed on approved scales. Dial scales shall have a capacity of not more than 15 percent of the capacity of the mixer. The value of the minimum graduation shall not be greater than 2 pounds. Except when a drier-drum mixing plant is used, the asphalt material bucket and its valves and spray bar shall be steam jacketed or heated by other Department approved means. The bucket shall have a capacity of at least 115 percent of the weight of the asphalt material required in any mixture and shall be supported by fulcrums. The asphalt shall be delivered to the mixer in multiple uniform streams for the full width of the mixer.
j.Proportioning Aggregates: Mineral filler and any bag house fines the Contractor uses shall be metered or introduced by means of an approved device for uniform proportioning by weight or by volume. The weigh hopper shall be of sufficient size to hold the maximum required weight of aggregate for one batch without hand raking or running over. Sufficient clearance between the weigh hopper and supporting devices shall be provided to prevent accumulation of foreign materials. The discharge gate of the weigh hopper shall be situated in such a manner that the aggregates will not segregate when dumped into the mixer. Gates on the bins and weigh hopper shall be constructed to prevent leakage when closed.
k.Drum Mixer: The aggregate shall be proportioned by a positive weight control at the cold aggregate feed by use of a belt scale that will automatically regulate the supply of material being fed and permit instant correction of variations in load. The cold feed flow shall be automatically coupled with the asphalt flow to maintain the required proportions.
l.Batch Mixer: shall be of a twin pugmill or other approved type, steam jacketed or heated by other approved means, and capable of producing uniform mixtures within the specified tolerances. It shall be equipped with a sufficient number of paddles or blades operating at such speeds as to produce a properly and uniformly mixed batch. The number and arrangement of the mixer paddles shall be subject to the Engineer’ s approval. Worn or defective blades shall not be used in mixing operations.211.12 183The mixer shall be provided with an approved time lock that will lock the discharge gate after the aggregates and asphalt have been placed in the mixer and will not release the gate until the specified time for mixing has elapsed. Batch-type mixing plants used to produce asphalt concrete shall be equipped with approved auto - matic proportioning devices. Such devices shall include equipment for accurately proportioning batches of the various components of the mixture by weight or volume in the proper sequence and for controlling the sequence and timing of mixing operations. The automated system shall be de - signed to interrupt and stop the batching operation at any time batch quantities are not satisfied for each of the materials going into the mix. A means shall be provided for observing the weight of each material during the batching operation. The aggregate may be proportioned by cold feed controls in lieu of plant screens provided the cold aggregate feed conforms to the requirements specified in (j) herein. Should the automatic proportioning devices become inoperative, the plant may be allowed to batch and mix asphalt materials for a period of not more than 48 hours from the time the breakdown occurs provided alternate proportioning facilities are verbally approved by the Engineer. Written permission of the Engineer will be required for operation without automatic proportioning facilities for periods longer than 48 hours.
m.Continuous Mixing Plant: shall include a means for accurately proportioning each size of aggregate either by weighing or volumetric measurement. When gradation control is by volume, the unit shall include a feeder mounted under the compartment bins. Each bin shall have an accurately controlled individual gate to form an orifice for volumetrically measuring the material drawn from each respective bin compartment. The orifice shall be rectangular, with one dimension adjustable by positive mechanical means, and shall be provided with a lock. Indicators shall be provided to show the individual gate opening in inches. The plant shall be equipped with a satisfactory revolution counter. The plant shall include a means for calibrating gate openings by weight. The materials fed out of the bins through individual orifices shall be bypassed to a suitable test box, with each component material confined in a separate section. The plant shall be equipped to conveniently handle test samples weighing up to 200 pounds per bin with accurate platform scales provided for this purpose. Positive interlocking control shall be provided between the flow of aggregate from the bins and the flow of asphalt material from the meter or other proportioning device. This shall be accomplished by approved interlocking devices or other approved positive means. Accurate control of the asphalt material shall be obtained by weighing, metering, or volumetric measurement. The aggregate may be proportioned by cold feed controls in lieu of plant screens provided the cold aggregate feed conforms to the requirements specified in (j) herein. The plant shall include a continuous mixer of an approved type that is steam jacketed or heated by other approved means. The paddles shall be of any adjustable type for angular position on the shafts and reversible to retard the flow of the mixture. Interlock cutoff circuits shall be included to interrupt and to stop the proportioning and mixing operations when the aggregate level in the plant or the asphalt material in storage falls below that necessary to produce the specified mixture.211.12 184(n) Trucks, Truck Scales, and Automatic Printer System: These shall conform to the requirements of Section 109.01.
211.13 Preparation of Mixture
The asphalt and aggregate shall be introduced into the mixer at a temperature that will produce a mixture that conforms to the requirements of the job-mix formula. After the required amounts of aggregate and asphalt material have been introduced into the mixer, the materials shall be mixed until a uniform coating of asphalt and a thorough distribution of the aggregate throughout the mixture are secured that comply with the requirements of the Ross count procedure in AASHTO T195. The wet mixing time, based on the procedures in AASHTO T195, shall be determined by the Contractor at the beginning of production and will be approved by the Engineer for each individual plant or mixer and for each type of aggregate used; however, in no case shall the wet mixing time be less than 20 seconds. The wet mixing time is the interval of time between the start of introduction of the asphalt material into the mixer and the opening of the discharge gate. A wet mixing time that results in fully coating a minimum of 95 percent of the coarse particles, based on the average of the three samples is acceptable, provided that none of the three sample results has a coating less than 92 percent of the coarse particles shall be the minimum wet mixing time requirement. A dry mixing time of up to 15 seconds may be required by the Engineer to accomplish the degree of aggregate distribution necessary to obtain complete and uniform coating of the aggregate with asphalt.
211.14 Storage System
If the Contractor elects to use a storage system, the system shall be capable of conveying the mix from the plant to the storage bins and storing the mix without a loss in temperature or segregation or oxidation of the mix. Storage time shall be limited by the ability of the bins to maintain the mix within the quality requirements specified herein with a maximum time limit not to exceed 10 days. Material may be stored in bins for no more than 24 hours without a Department approved heating system. The conveyor system may be a continuous or skip bucket type. Continuous type conveyors shall be enclosed so that the mix temperature is maintained. The storage bins shall be designed in a manner to prevent segregation of the mix during discharge from the conveyor into the bins and shall be equipped with discharge gates that will not cause segregation of the mix while the mix is being loaded into the trucks. Approval for the use of storage bins may be withdrawn by the Engineer if the amount of heat loss, segre - gation, or oxidation of the mix is excessive.
211.15 Initial Production
a.Warm Mix Asphalt (WMA): At the start of production, the Contractor shall place no more than 500 tons or up to one day’ s production as directed by the Engineer at an approved site, which may be the project site, so the Engineer can examine the process control of the mixing plant, the Contrac -211.12 185tor’ s placement procedures, surface appearance of the mix, compaction patterns of the Contractor’ s roller(s), and correlation of the nuclear density device.
b.Hot Mix Asphalt (HMA): At the start of production of a mix not previously used on a state roadway, the Contractor shall place 100 to 300 tons or up to one day’ s production as directed by the Engineer at an approved site, which may be the project site, so the Engineer can examine the process control of the mixing plant, the Contractor’ s placement procedures, surface appearance of the mix, compaction patterns of the Contractor’ s roller(s), and correlation of the nuclear density device. The material shall be placed at the specified application rate. The Engineer will determine the disposition of material that was not successfully produced and/or placed due to negligence in planning, production, or placement by the Contractor. SECTION 212—JOINT MATERIALS
212.01 Description
These specifications cover resilient products made from various materials that are designed to accommo - date the movement of rigid structures, such as component parts of hydraulic cement concrete, and seal the joint from intrusion of water or incompressibles.
212.02 Detail Requirements
a.Hot-poured joint sealer shall be heated in accordance with the manufacturer’ s recommendations.
1.Asphalt sealer shall conform to ASTM D6690, Type II.
2.Elastomeric joint sealer shall conform to ASTM D3406 and shall only be used for longitudinal joints.
b.Silicone sealants shall be furnished in a one- or two-part formulation. The sealant shall be compatible with the surface to which it is applied. Acid-cure sealants are not acceptable for use on hydraulic cement concrete. Bond breakers shall be chemically inert and resistant to petroleum products, solvents, and primers. Silicone sealants are identified in the following manner:
1.Class A: A low-modulus non-sag silicone for use in sealing horizontal and vertical joints in hydraulic concrete pavements and structures. Tooling is required.
2.Class B: A very-low-modulus self-leveling silicone used to seal horizontal joints in hydraulic cement concrete pavements and structures. Tooling is not normally required.
3.Class C: An ultra-low-modulus self-leveling silicone used to seal horizontal joints in hydraulic cement concrete pavements and structures. It can also be used to seal the joints between hydraulic cement concrete pavement and asphaltic concrete shoulders. Tooling is not normally required.212.02
Source: Virginia Road and Bridge Specifications, 2020 Edition. Pages 192–212 of 1,065.