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. 120 ALASKA 2020 4. Crushed Asphalt Base Course, by lump sum . Emulsified Asphalt is subsidiary.
308-5.01 BASIS OF PA YMENT. Additional crushed aggregate base course, if required, will be
paid for under Section 301. Water required for compaction of the crushed asphalt base course is subsidiary. Payment will be made under: PAY ITEM Item Number Item Description Unit 308.0001.____ Crushed Asphalt Base Course SY 308.0002.____ CSS-1 for Asphalt Base Course TON 308.0003.____ Crushe d Asphalt Base Course TON 308.0004.____ Crushed Asphalt Base Course LS 121 ALASKA 2020 DIVISION 400 –ASPHAL T PAVEMENTS AND SURFACE TREATMENTS SECTION 401 HOT MIX ASPHALT PAVE MENT
401-1.01 DESCRIPTION . Construct one or more courses of plant -produced Hot Mix Asphalt
(HMA) pavement on an approved surface, to the lines, grades, and depths shown on the Plans. MATERIALS
401-2.01 ASPHALT BI NDER . Conform to Subsection 702- 2.01. Asphalt binder may be
conditionally accepted at the source providing a manufacturers certificati on of compliance according to Subsection 106- 1.05, and test results of the applicable requirements of Section 702. Use PG 52 -28 if no Grade is specified.
401-2.02 LIQUID ANT I-STRIP ADDITIVE. Use anti -strip agents in the proportions determined
by ATM 414 and included in the approved Job Mix Design (JMD). At least 90 percent of the aggregate must remain coated when tested according to ATM 414. The following minimum dose (percent) of liquid anti -strip by weight of asphalt binder is required:
401-2.03 JOINT ADHE SIVE. Conform to Subsection 702- 2.05.
401-2.04 JOINT SEAL ANT. Conform to Subsection 702- 2.06.
401-2.05 WARM MIX ASPHALT . Conform to Subsection 702- 2.07.
401-2.06 ASPHALT RE LEASE AGENT . Conform to Subsection 702- 2.08.
401-2.07 AGGREGATES . Conform to Subsection 703- 2.04. Use a minimum of three stockpiles
of crushed aggregate (coarse, intermediate, and fine). Place blend material, if any, in a fourth pile.
401-2.08 RECYCLED A SPHALT PAVEMENT . Recycled asphalt pavement (RAP) may be used
in the production of HMA. The RAP may be from pavements removed under the Contract, or from an existing stockpile. Conform to Subsection 703 -2.16.
401-2.09 JOB MIX DES IGN. Provide target values for gradation that satisfy both the broad band
gradation limits shown in Table 703- 4 and the requirements of Table 401- 1, for the Type and Class of HMA specified. TABLE 401 -1 HMA MARSHALL DESIGN REQUIREMENTS DESIGN PARAMETER CLASS “A” CLASS “B” HMA (Including Asphalt Binder) Stability, Pounds 1800 Min. 1200 Min. Flow, 0.01 Inch 8 – 14 8 - 16 Voids in Total Mix (VTM), % 3.0 – 5.0 3.0 – 5.0 Compaction, Number of Blows Ea ch Side of 75 50 Liquid Anti -strip Type Minimum Dose by Weight of Asphalt Binder, % Amines based 0.30 Phosphate Ester based 0.30 Organo -Silane based 0.05
Source: Alaska Standard Specifications for Highway Construction, 2020 Edition. Pages 147–148 of 584.