2210.01 GENERAL.
This work consists of preparing the subgrade, providing for a filter course, furnishing, placing, and compacting a Macadam base course and a choke stone course, and applying a prime to the finished work, prior to placement of a surface course, all in accordance with the contract documents.

2210.02 MATERIALS.
Aggregate for the base course and choke stone course shall meet requirements of Article Section 4122.

Primer bitumen shall be SS-1, SS-1H, CSS-1, or CSS-1H, meeting requirements of Section 4140. RC-70 and MC-70 may also be used after October 1, and the Contractor's option.

2210.03 EQUIPMENT.
Equipment shall meet requirements of Section 2001 and the following:

A. Weighing Equipment.
Article 2001.07 shall apply.

B. Compaction Equipment.
Article 2001.05, F, shall apply. In addition, a smooth faced, steel tired roller, meeting requirements of Article 2001.05, B, will be required for final rolling of the choke stone course.

C. Prewetting Equipment.
Article 2001.08, A, shall apply if prewetting is to be done.

D. Spreading Equipment.
Spreading equipment shall be capable of spreading the base and choke stone course to the required thickness.

E. Broom.
Article 2001.14 shall apply.

F. Equipment for Heating and Distributing Bitumen.
Articles 2001.11 and 2001.12 shall apply.

G. Equipment for Applying Water.
Article 2001.09 shall apply.

H. Motor Graders.
Article 2001.15 shall apply.

2210.04 PREPARATION OF THE SUBGRADE.
The subgrade shall be corrected and constructed with provision for a filter course as required by the contract documents. Macadam stone base is not to be constructed on natural soil subgrade.

2210.05 MACADAM BASE COURSE.
Base material shall be spread to a width and depth so the base will conform to the desired profile and cross section. The maximum compacted thickness of base material which may be spread for compaction as a single course will be limited to that which will be uniformly and satisfactorily compacted for the full depth of such course by the compaction equipment employed. The spreading shall be done in such a way that uniformity of the base material is maintained. When a spreader does not spread to the full design width in one operation, the Engineer may require special handling of the center joint to avoid segregation.

Promptly after the material has been spread, it shall be thoroughly and uniformly compacted. Compaction shall continue until the base material is well seated and no appreciable displacement occurs when rolling.

2210.06 CHOKE STONE COURSE.
The aggregate may be prewetted before delivery to the Macadam stone base. The Engineer may control the rate of delivery of material to reduce the time material will remain on the base in an uncompacted condition to the practical minimum.

If the material is prewetted before delivery, or if water is added after delivery to the base, water shall be uniformly distributed throughout the material so that all particles are uniformly wet. The amount of water shall be within 2.0 percentage points of the amount determined as field optimum to produce maximum density together with stability with the field compaction procedure. This moisture content will usually be 85 to 90% of the optimum determined according to Iowa DOT Materials Laboratory Test Method 103. This moisture content shall be maintained in the material until compaction of the base has been completed.

The choke stone course shall be spread as required for the Macadam base course.

Promptly after the material has been spread, it shall be thoroughly and uniformly compacted by three passes of a vibratory roller. During the compaction process, such wetting, shaping, and edge trimming shall be performed as may be necessary to insure proper compaction and to achieve the required profile, crown, cross section, and edge alignment. An additional final rolling with a smooth faced, steel tired roller will be required. The finished surface of the base shall be free from irregularities and loose material and shall have a smooth riding surface.

2210.07 FILLETS FOR INTERSECTING ROADS, DRIVES, AND TURNOUTS.
Fillets shall be constructed according to the contract documents.

2210.08 PRIMING BASE COURSE.
The surface of the choke stone course and adjacent subgrade shall be primed in accordance with the contract documents.

2210.09 MAINTENANCE OF COMPLETED BASE.
The base may be completed as far in advance of the course to be superimposed thereon as the Contractor may elect.

The Contractor is responsible for maintenance of the completed base to the required density, cross section, and smooth condition free from loose material prior to and during subsequent construction activities. Hauling equipment or other traffic shall not be allowed on the completed base.

Should traffic by others authorized to do work on the project be specifically permitted by the Engineer to exceed the Contractor's self imposed limit, during base construction, the Contracting Authority will pay the repair costs set by the Engineer representing an increase in cost of repair of damage, if any, caused by such traffic.

2210.10 WINTER SEAL.
All base which is not covered with upper base or surface in the same construction season in which it is built shall be primed, as specified, and in addition, the Engineer may require an application of a winter seal. Except as modified by the Engineer, the winter seal shall consist of the bituminous material used as the primer or tack coat applied at 0.12 gallon per square yard (0.5 L/m²) and a sand cover applied at 10 to 15 pounds per square yard (5 to 8 kg/m²), in accordance with Section 2307. Winter seal required by the Engineer will be paid for as provided in Article 1109.03, B.

Except where road closure is provided in the contract documents, traffic will be allowed to use the road from the time construction is stopped until work is resumed the following season. Any repairs to the base required when construction is resumed shall be made by the Contractor at no additional cost.

2210.11 METHOD OF MEASUREMENT.
The quantities of the various classes of work involved in the construction of accepted portions of Macadam stone base will be measured by the Engineer as follows:

A. Macadam Stone Base.
Macadam stone base will be measured in tons (megagrams) computed by the Engineer from weights (mass) of individual truck loads.

B. Choke Stone Base.
Choke stone base will be measured in tons (megagrams) computed by the Engineer from weights (mass) of individual truck loads, including free moisture in the material at the time of delivery. Moisture added after delivery of the material to the roadbed will not be measured for payment.

C. Primer Bitumen for Macadam Stone Base.
Article 2307.06, B, shall apply.

2210.12 BASIS OF PAYMENT.
For the performance of the various classes of work involved in construction of Macadam stone base, measured as provided above, the Contractor will be compensated as follows:

A. Macadam Stone Base.
For the number of tons (megagrams) of Macadam Stone Base placed, the Contractor will be paid the contract unit price per ton (megagram.

B. Choke Stone Base.
For the number of tons (megagrams) of Choke Stone Base placed, the Contractor will be paid the contract unit price per ton (megagram).

C. Primer Bitumen for Macadam Stone Base.
For the number of gallons (liters) of Primer Bitumen for Macadam Stone Base measured for payment, the Contractor will be paid the contract unit price per gallon (liter).

These payments shall be full compensation for furnishing all materials, including water, and for all operations involved in the construction of the base.