116 ALASKA 2020 SECTION 307 EMULSIFIED ASPHALT T REATED BASE COURSE
307-1.01 DESCRIPTION . Construct an emulsified asphalt treated base (EATB) course on a
prepared foundation to the lines, grades, and depths shown on the Plans.
307-2.01 MATERIALS. Use materials that conform to the following:
Aggregate Subsection 703- 2.03 Asphalt Section 702, for the type and grade shown on the bid schedule Use PG 52 -28 if no Grade is specified Anti-Strip As required by the approved Job Mix Design Portland Cement Section 701 (Type I)
307-2.02 COMPOSITION OF MIXES. At least 15 days in advance of the production of EATB
material, furnish a representative 300- pound sample of the base aggregate proposed for the project, and a representative 3- gallon sample of the asphalt binder, and a one- pint sample of antistrip additive if used in the mix. The Engineer will determine the job mix design. Changes in aggregate gradation or aggregate sources will require a new job mix design. Submit samples in the same manner as the original submittal. Use anti -strip agents in the proportions determined by ATM 414 and included in the approved Job Mix Design. At least 70 percent of the aggregate must remain coated when tested by ATM 414. CONSTRUCTION REQUIREMENTS
307-3.01 Mixing.
1.Mix EATB material either
a.at an approved central mixing plant,
b.in place, on an approved subgrade, or
c.on an approved mixing area. If method b. or c. above is used, prevent contamination of the base course material by the underlying material. Adjust aggregate moisture content prior to asphalt application. Apply portland cement, if required, to the aggregate immediately prior to mixing. Acceptance of aggregates will be based upon representative samples taken just prior to the addition of the emulsified asphalt.
2.Central plants may be either batch or continuous twin- shaft pugmill units equipped with adequate proportioning devices to control aggregate, asphalt, water and portland cement. Combine the aggregate, emulsified asphalt, portland cement , and water, in the mixing plant in the specified proportions. Adjust the mixing time to the minimum time which will provide a complete coating of the aggregate particles.
3.Perform in- place mixing with single or double pugmill travel plants, rotary cross -shaft mixers, or motor grader (blade). Equip travel plants and cross -shaft mixers with adequate proportioning devices to control asphalt. Use distributors for applying asphalt for in- place blade mixing which conform to Subsection 402- 3.02. 117 ALASKA 2020 Mix aggregates, asphalt material and additives until a uniform coating of aggregate particles is attained.
307-3.02 WEATHER LIM ITATIONS. Do not mix or place EATB material until the aggregate
temperature is above 40 °F and the air temperature as measured in the shade and a way from any heat source is 45 °F and rising. Do not place the EATB material on a wet or frozen surface, or when weather conditions will prevent proper handling, compacting, finishing, or curing of the mixture.
307-3.03 OPERATIONAL LIMITATIONS. Coordinate the various portions of the work to conform
to the traffic maintenance requirements of Section 643. Place EATB materials only on an accepted subgrade. Ensure that the subgrade surface is substantially true to line and grade, firm and reasonably smooth, an d free of loose or objectionable material, before placement of EATB materials.
307-3.04 Equipment.
1.Mixing Plant . Conform to Subsection 401- 3.05.
2.Hauling Equipment . Conform to Subsection 401- 3.06.
3.Spreading Equipment . Self -propelled paving machine conf orming to Subsection 401- 3.07 or motor grader.
4.Rollers . Conform to Subsection 401- 3.08.
307-3.05 SPREADING A ND FINISHING. Spread EATB material in single lifts not to exceed 6
inches. If the single lift cannot be compacted sufficiently to conform to Subsec tion 307- 3.06, spread and compact in multiple lifts of equal thickness.
307-3.06 COMPACTION. The Engineer will use ATM 412 to determine the density standard.
Make each control strip at least 12 feet by 300 feet. Compact the remainder of the project to not less than 98 percent of the density standard, in accordance with ATM 411. The Engineer will designate the location of test strips. Compact the EATB using at least one pneumatic roller and one vibratory roller. Use vibratory compactors, applying a minimum dynamic force of 50,000 pounds per vibration at a minimum frequency of 1,000 vibrations per minute. Adjust working speed in order to apply 8 to 12 impacts per foot. In areas inaccessible to rollers, use mechanical tampers until thoroughly compacted.
307-3.07 SURFACE TEST. After rolling has been completed, the surface will be tested for
smoothness and accuracy of grade, crown, superelevation, and width. Limit surface deviations to 3/8 inch, as measured from the testing edge of a 10- foot straightedge between two contacts with the surface parallel with, and at right angles to, the centerline.
307-3.08 THICKNESS R EQUIREMENTS. Limit deviations in thickness to 1/2 inch.
307-4.01 Method of M Easurement.
1.EATB. See Section 109 . No deduction will be made for the wei ght of asphalt material or for water added to provide optimum moisture content in the mix.
2.Emulsified Asphalt . By supplier's invoice quantity minus waste, diversion and remnant. 118 ALASKA 2020 307-5.01 BASIS OF PA YMENT. When Pay Item 307.0002.____ does not appear in t he bid schedule, emulsified asphalt material is subsidiary. Payment will be made under: PAY ITEM Item Number Item Description Unit 307.0001.____ EATB TON 307.0002.____ Emulsified Asphalt, Type ____ TON 307.0003.____ EATB, ___ in. thick SY 119 ALASKA 2020 SECTIO N 308 CRUSHED ASPHALT BASE COURSE
308-1.01 DESCRIPTION . Construct a base course, using pulverized asphalt pavement, to the
grades shown on the Plans. Add emulsified asphalt to the base course mixture, when shown on the plans.
308-2.01 MATERIALS. Use materi als that conform to the following:
Asphalt Concrete Existing asphalt pavement material Aggregate Base Course Subsection 703- 2.03 Emulsified Asphalt Section 702 (CSS -1) CONSTRUCTION REQUIREMENTS
308-3.01 PULVERIZING AND MIXING. Crush or process the existing asphalt pavement so that
100 percent by weight passes the 2- inch sieve and 95- 100 percent by weight passes the 1- 1/2- inch sieve. Use self -propelled pulverizing and mixing equipment capable of processing to full depth in a single pass. If emulsified asphalt is called for on the Plans, the mixing equipment must also be capable of adding the emulsion, through a metered system during mixing. Add crushed aggregate base course to the base course mixture as needed to conform to the design grade.
308-3.02 WEATHE R LIMITATIONS. Do not use any frozen material or compact on a frozen
base.
308-3.03 SHAPING AND GRADING. Use a finish grader that is equipped with an automatic
grade and cross slope control system. Maintain longitudinal grade control, based on either stri ng line or the existing roadway surface, as determined by the Engineer.
308-3.04 COMPACTION AND COMPACTION EQUIP MENT. The Engineer will use ATM 412 to
determine the density standard. Make each control strip at least 12 feet by 300 feet. Compact the remainder of the project to not less than 98 percent of the density standard, in accordance with ATM 411. The Engineer will designate the location of test strips. Compact the base course using vibratory compactors, applying a minimum dynamic force of 50,000 pounds per vibration at a minimum frequency of 1,000 vibrations per minute. Adjust working speed in order to apply 8 to 12 impacts per foot. In areas inaccessible to rollers, use mechanical tampers until thoroughly compacted.
308-3.05 SURFACE TEST. The finished surface will be tested for smoothness and accuracy of
grade, crown, superelevation, and width. Limit surface deviations to 3/8 inch, as measured from the testing edge of a 10- foot straightedge between two contacts with the surface parallel with, and at r ight angles to, the centerline.
308-4.01 METHOD OF M EASUREMENT. See Section 109 and the following:
1.Crushed Asphalt Base Course, by square yard . By the area of finished top surface.
2.CSS- 1 Asphalt for Base Course, by ton . By weighing or invoice.
3.Crushed Asphalt Base Course, by ton. By weighing or invoice.
Source: Alaska Standard Specifications for Highway Construction, 2020 Edition. Pages 144–146 of 584.