161 ASPHALT BASE, WEARING, AND PATCHING AND LEVELING COURSES
401.1 -DESCRIPTION : This work shall consist of constructing one or more courses of asphalt concrete, mixed mechanically in a plant, composed of aggregate and asphalt material designed in accordance with either the Marshall or Superpave design system as specified in the contract documents, on a prepared foundation in accordance with these specifications and in r easonable close conformity with the lines, grades, weights or thicknesses, and cross sections shown on the Plans or established by the Engineer. The unit of measurement for asphalt concrete will be by the ton, square yard or cubic yard. The work will be accepted in accordance with these Specifications and the applicable requirements of Sections 105, 106, and 109.
401.2 -MATERIALS : The materials shall conform to the following requirements:
MATERIAL SUBSECTION Coarse Aggregate 703.1 thru 703.3 Note 1 & Note 2 (See MP 401.02.28 for exceptions and additions required for Superpave Items.) Fine Aggregate 702.3 (See MP 401.02.28 for additions required for Superpave Items) Mineral Filler 702.4 Performance Graded Binders 705.5
Note 1 The total shale, coal and other lightweight deleterious material and friable particles shall not exceed 3%. Note 2 When slag is specified in the contract, the coarse aggregate shall be slag which meets the requirements of 703.3, except as amended in this subsection.
401.2.1 –Performance Graded Binder Grade: The standard grade for Performance Graded (PG) binders shall be PG 64S -22, any deviation will be noted in the contract documents. PG 64H -22 shall be used on projects specified with over 20 million ESALs over the design life. PG 64S -22 binder may be used in asphalt placed below the top two lifts in any pavement section, scratch course and patching -and-leveling are not ide ntified as lifts.
CONSTRUCTION METHODS
401.3 -GENERAL : Construction methods to be used in performing the work shall be submitted to the Engineer for review prior to the start of work. This review may require modification of the proposed methods to provide the desired end product. All equipment, tools, machinery, and plant shall be maintained in a satisfactory working condition.
162 401.4 -COMPOSITION OF MIXTURES : 401.4.1 -General : The aggregate for use in the designated mixture shall consist of a mixture of aggregate (coarse, fine, reclaimed asphalt pavement (RAP) if desired, or mixture thereof) and mineral filler if required. It shall be the responsibility of the Contractor to determine the percentage of RAP to be used in the mix. The amount and grade of virgin PG Binder to be used in the RAP designs shall be determ ined in accordance with Materials Procedure
401.4.2 -Job Mix Formula : Job Mix Formula (JMF) is the specification for a single mix produced at a single plant. This mix may be specific to a single project or be used on multiple projects if the basic design criteria (design compaction level and PG Binder grade) are the same. The Contractor shall submit a proposed JMF for each combination of aggregate and asphalt material for each type of asphalt concrete to be produced. Dependi ng on the design type, the JMF gradations shall be within the tolerances set forth in either Table 401.4.2A or Table 401.4.2B. Marshall mix designs shall be developed in accordance with MP 401.02.22. Superpave mix designs shall be developed in accordance with MP 401.02.28. Each proposed JMF must be documented on the Division Form T400 and the entire JMF package shall be forwarded for review to the District Materials Engineer/Supervisor. The T400 and JMF package shall then be transmitted to the Materials Control, Soils and Testing Division for final review. If the JMF requires revision, it will be returned to the designer through the District. The T400 Form shall contain the following information:
ii. The aggregate blend percentages and the percentage for each sieve fraction of aggregate considered the desirable target for that fraction. iii. The percentage of asphalt binder representing the optimum asphalt content for the JMF submitted, wh ich is to be considered the desirable target percentage. iv. The temperature of the completed mixture at the plant which shall be within ± 25°F of the median mix temperature established by the temperature -viscosity chart or as recommended by the asphalt supplier.
Marshall mixes the ratio is defined as the percentage of aggregate passing the No. 200 (75 µm) sieve, divided by the percentage of asphalt content calculated at the percentage optimum asphalt content of the design. For Superpave mixes the ratio is defined as the percentage of aggregate passing the 75 µm (No. 200) sieve, divided by the percentage of effective asphalt content calculated at the percentage optimum as phalt content of the design.
163 TABLE 401.4.2A Design Aggregate Gradation Requirements for Marshall Mix Designs Type of Mix Base -I Base -II (Patch & Level) Wearing IV Wearing -I (Scratch -I) Wearing -III (Scratch -III) Sieve Size Nominal Maximum Size 1 ½ in (37.5 mm) ¾ in (19 mm) ¾ in (19 mm) 3/8 in (9.5 mm) No. 4 (4.75 mm) 2 in (50 mm) 100 – – – – 1 ½ in (37.5 mm) 90-100 – – – – 1 in (25 mm) 90 max 100 100 – – ¾ in (19 mm) – 90-100 90-100 – – ½ in (12.5 mm) – 90 max 90 max 100 – 3/8 in (9.5 mm) – – – 85-100 100 No. 4 (4.75 mm) – – 47 min 80 max 90-100 No. 8 (2.36 mm) 15-36 20-50 20-50 30-55 90 max No. 16 (1.18 mm) – – – – 40-65 No. 30 (600 µm) – – – – – No. 50 (300 µm) – – – – – No. 200 (75 µm) 1-6 2-8 2-8 2-9 3-11
164 TABLE 401.4.2B Design Aggregate Gradation Requirements for Superpave Mix Designs Type of Mix 37.5 25 19 Note 1 (Patch & Level) 12.5 9.5
(Scratch) Standard Sieve Size Nominal Maximum Size 37.5 mm (1 ½ inch) 25 mm (1 inch) 19 mm (3/4 inch) 12.5 mm (1/2 inch) 9.5 mm (3/8 inch) 4.75 (No. 4) 50 mm (2”) 100 – – – – – 37.5 mm (1½”) 90-100 100 – – – – 25 mm (1”) 90 max 90-100 100 – – – 19 mm (3/4”) – 90 max 90-100 100 – – 12.5 mm (1/2”) – – 90 max 90-100 100 100 9.5 mm (3/8”) – – – 90 max 90-100 95-100 4.75 mm (No.4) – – – – 90 max 90-100 2.36 mm (No.8) 15-41 19-45 23- 49 28-58 32-67 1.18 mm (No.16) – – – – – 30-60 600 µm (No.30) – – – – – – 300 µm (No. 50) – – – – – – 75 µm (No.200) 0-6 1-7 2-8 2-10 2-10 6-12
Note 1 When a 19 mm mix is specified for use as a heavy duty surface mix, it shall be designed as a fine graded mix with the additional requirement of a minimum of 47% passing the 4.75 mm (No.4) screen.
If it becomes necessary to change aggregate sources, a new mix design shall be developed and submitted for approval. When using neat (unmodified) PG Binders, the binder source may be changed without requiring a new mix design, but the binder grade must always remain the same for each design. If a source change resul ts in the use of an additive - enhanced modified binder of the same grade, a new mix design will be required. If a modified binder source is changed or if the modification process is changed, a new mix design shall be developed and submitted for approval. A source change to a new location with the original manufacturer/supplier and the original modification process will not require a new mix design. At no time shall different grades of PG Binders be mixed together in the same storage tank. When it is n ecessary to switch to a new binder grade the tank shall be drawn down as far as possible, normally to the top of heating coils, before refilling with the new binder. The new binder shall be circulated thoroughly before restarting production.
401.4.2.1 -Warm Mix Asphalt: When the Division allows an approved asphalt concrete design to be produced as warm -mix asphalt (WMA) using the water injection system, the temperature of the completed mixture at the plant may be lowered to an established range that has previously been determined through trial production. The allowable temperature range specified on the approved T400 mix design form shall be
165 adjusted accordingly when producing WMA. In addition, all references to the minimum compaction temperatures in Sections 401.10.3 and 401.10.4 of this specification, may be waived if it can be established that additional density can be obtained at lower temperatures without damaging the pavement . Intermingling of WMA with non WMA materials on the same course should b e avoided. If circumstances result in the need for intermingling, it must be approved by the Engineer. Upon approval, the location where intermingling occurs on the project shall be clearly defined and documented by the Contractor and submitted to the Engineer. If the intermingling occurs on a project where the density of the pavement is being controlled by the rollerpass compaction method, then a new test section shall be established on the new material beginning at the point where the WMA and standard asphalt concrete material meet. If the intermingling occurs on a project where the density is controlled via Lot by Lot testing, the location should be clearly marked so that the correct maximum theoretical density can be used. All testing requirementses tablished for standard asphalt concrete mix designs and quality assurance/quality control testing shall also apply to WMA.
401.5 -TESTING : 401.5.1 -Procedures: AASHTO R 47 Reducing Samples of Asphalt Mixtures to Testing Size AASHTO R 68 Preparation of Asphalt Mixtures by Means of The Marshall Apparatus AASHTO T 11 Materials Finer Than No. 200 (75 µm) Sieve in Mineral Aggregates by Washing AASHTO T 27 Sieve Analysis of Fine and Coarse Aggregates AASHTO T 30 Mechanical Analysis of Extracted Aggregate AASHTO T 164 Quantitative Extraction of Asphalt Binde r from HMA AASHTO T 166 Bulk Specific Gravity (Gmb) of Compacted Asphalt Mixtures Using Saturated Surface -Dry Specimens AASHTO T 168 Sampling Bituminous Paving Mixtures AASHTO T 209 Maximum Specific Gravity and Density of Asphalt Mixtures AASHTO T 245 Resistance to Plastic Flow of Asphalt Mixtures Using Marshall Apparatus AASHTO T 308 Asphalt Binder Content of Asphalt Mixtures by the Ignition Method (Test Method A) AASHTO T 312 Preparing and Determining the Density of Asphalt Mixture Specimens by Means of the Superpave Gyratory Compactor AASHTO T 355 Standard Method of Test for In -Place Density of Asphalt Mixtures by Nuclear Methods ASTM D5581 Resistance to Plastic Flow of Bituminous Mixtures Using Marshall Apparatus (For Base -I Marshall Designs) MP 700.00.06 Aggregate Sampling Procedures
401.6 -CONTRACTORS QUALITY CONTROL : 401.6.1 -Quality Control Testing : Quality control of bituminous as phalt is the responsibility of the Contractor. The Contractor shall maintain equipment and qualified personnel including at least one certified Asphalt Plant Technician at each plant. The technician shall be in charge of all plant quality control activities such as mix proportioning and adjustment and all sampling and testing activities necessary to maintain the various properties of asphalt within the limits of the specification.
166 The Contractor shall maintain necessary equipment and qualified personnel i ncluding at least one certified Asphalt Field and Compaction Technician at each project during paving operations. Additionally, a certified Asphalt Field and Compaction Technician with certification to perform nuclear density testing of asphalt pavementss hall perform all testing necessary to assure compaction of the asphalt meets specification requirements. The Contractor, shall design a workable Quality Control Plan, detailing the type and frequency of sampling and testing deemed necessary to measure and control the magnitude of the various properties of the asphalt governed by these specifications. This plan, prepared in accordance with MP 401.03.50 shall be submitted to the Engineer for review prior to production of material under this specif ication.
401.6.2 -Job Mix Formula (JMF) Field Verification : For each JMF, a mix design field verification shall be conducted during the first days of plant production. For Marshall designs, the verification shall be in accordance with the guidelines established in MP 401.02.27. For Superpave, designs it shall be in accordance with MP 401.02.29. The field verification is for the purpose of demonstrating that the JMF can be produced within the specified tolerances set forth in the MP. If t he mix cannot be produced within these requirements, a new mix design will be required.
401.6.3 -Quality Control Testing Requirements: After the JMF design field verification has been successfully completed, sampling frequency and test requirements for quality control shall be as set forth in MP 401.02.27 for Marshall designs and MP 401.02.29 for Superpave designs. If the Division determines that a mix cannot be consistently produced within the tolerance limits of the specified design properties, approval of the mix may be revoked and the contractor will be required to provide a new mix design.
401.6.4 -Compaction : Projects shall be tested for compaction in accordance with the Lot - by-Lot test method described in Section 401.6.4.2 if the project limits meet all of the following requirements:
If a project does not meet the above criteria, testing for compaction shall be in accordance with the Rollerpass test method described in Section 401.6.4.3. In addition, areas of Trench Paving, Pavement Widening, and Pavement Repairs shall be tested in accordance with the Rollerpass test method or to the satisfaction of the Engineer. When asphalt is placed in areas that require a non -uniform thickness and tapers to a thin edge including patch and level and scratch, acceptance testing of the material is not required. Compaction shall be accomplished with a minimum of eight (8) roller passes prior to reaching the temperature specified in section 401.10.4. A pass shall be defined as the entire roller traversing a spot on the pavement. Compaction shal l be performed by a three -wheel (steel) roller or pneumatic -tire roller. Acceptance testing is not required on areas which are too narrow to be compacted with the roller use for the mainline paving, as defined in the contractor’s QC plan; such areas shal l be compacted to the satisfaction of the Engineer.