107 ALASKA 2020 DIVISION 300 –BASES AGGREGATE BASE AND S URFACE COURSE
301-1.01 D ESCRIPTION. Construct an aggregate base course or aggregate surface course on
an approved foundation, as shown on the Plans.
301-2.01 MATERIALS. Use aggregate conforming to Subsection 703- 2.03.
Crushed glass may be combined with soil -aggregate material to be used in base course construction. Meet 703- 2.15 requirements. CONSTRUCTION REQUIREMENTS
301-3.01 PLACING. Place material in layers not exceeding 8 inches in depth.
Maintain the roadway surface to drain freely at all times. When paving is specified in the Contract, schedule the work so that any base course placed will be covered prior to winter shutdown. Place surfacing material over all soil -aggregate bases containing glass cullet. Do not place base course soil -aggregate containing glass cullet:
1.Within four feet from the face of any embankment slope,
2.Within 150 feet from any surface water body,
3.In embankment areas where culvert placement is required,
4.In contact with any geosynthetic material.
301-3.02 MIXING. Mix the aggregate, incorporating any specif ied additives. Add water, as
needed, to provide the approximate optimum moisture content for compaction. Mix the aggregate by one of the following methods:
1.Stationary Plant Method
2.Travel Plant Method
3.Road Mix Method The aggregate will be accepted for gradation based on random samples taken for each lift from the roadway after spreading but prior to compaction.
301-3.03 SHAPING AND COMPACTION. The maximum density and optimum moisture will be
determined by ATM 207 or ATM 212. Spread and shape the material to the required grade and section. Water or aerate as necessary to provide the approximate optimum moisture content for compaction. Compact each layer to a density of not less than 98 percent of the maximum density. Acceptance densities will be determined by ATM 213 and ATM 214. Maintain the surface of each layer during the compaction operations in such manner that a uniform texture is produced and the aggregates firmly keyed. 108 ALASKA 2020 The finished surface will be tested using a 10- foot straightedge at selected locat ions. Limit surface deviations to 3/8 inch, as measured from the testing edge of the straightedge between two contacts with the surface.
301-4.01 METHOD OF MEASUREMENT. See Section 109, by volume in final position or by
weight.
301-5.01 BASIS OF PA YMENT. Water for compaction, added to the aggregate on the grade, is
subsidiary. Payment will be made under: PAY ITEM Item Number Item Description Unit 301.0001.____ Aggregate Base Course, Grading ____ TON 301.0002.____ Aggregate Base Course, Grading ____ CY 301.0003.____ Aggregate Surface Course, Grading ___ TON 301.0004.____ Aggregate Surface Course, Grading ___ CY 109 ALASKA 2020 SECTION 302 SUBGRADE MODIFICATIO N
302-1.01 DESCRIPTION . Scarify the existing road surface, incorporate aggregate and additives,
if required , and grade and compact the material to the typical section shown on the Plans. Realign the shoulders and clean and reshape the ditches, if required on the Plans.
302-2.01 MATERIALS. As shown on the Plans or specified in the Special Provisions.
CONSTRUCTI ON REQUIREMENTS
302-3.01 PROCESSING. Blade the shoulder slopes and ditches to form a uniform shoulder line.
First remove and dispose of weeds, sod, grass, roots, or other objectionable material from the surface. Spread the useable material obtained from the shoulder slopes and ditches and the surfacing material existing on the road surface uniformly over the roadbed. Scarify the road surface to the depth specified. Pulverize lumps as needed so that not more than 5 percent of the material exclusive of gravel or stone is retained on a 2- inch sieve. Mix material thoroughly. Form the mixed material into a uniform windrow. Place the quantity of aggregate for subgrade modification, as designated on the Plans, in a uniform windrow. Blend the windrowed materials t ogether until all materials are uniformly distributed throughout the combined windrow. Aggregate will be accepted at the point of production based on periodic samples. Spread the material uniformly to the required cross section and compact to meet Subsec tion 203- 3.04. When the material being compacted contains a significant quantity of pulverized asphalt, adequacy of compaction will be determined by alternative methods acceptable to the Engineer.
302-3.02 FINISHING. The finished surface will be tested usi ng a 10- foot straightedge at selected
locations. Limit surface deviations to 1- 1/4 inches, as measured from the testing edge of the straightedge between two contacts with the surface. If a base or surface course is included in the Contract, maintain the s urface of the completed subgrade until the base or surface course has been placed.
302-4.01 METHOD OF M EASUREMENT. See Section 109 and the following:
Aggregate for subgrade modification is weighed or measured in the hauling vehicle. Processing for subgrade modification is measured along centerline.
302-5.01 BASIS OF PA YMENT. The contract price for processing includes all blading of ditches
and shoulders, if called for on the Plans; scarifying and pulverizing of the existing surface; all placing and mixing of materials on the road; disposal of unsuitable material; the compacting of the materials; the finishing of the surface; and the maintenance of the completed surface when applicable Water for compaction added to the aggregate on the grade is subsidiary.
Source: Alaska Standard Specifications for Highway Construction, 2020 Edition. Pages 135–136 of 584.