Section 4121. Granular Subbase Material

 

4121.01 DESCRIPTION.

Aggregate of the following types:

         Crushed stone,

         Gravels of which 30% or more of the particles retained on the 3/8 inch (9.5 mm) sieve have at least one fractured face as defined in Materials I.M. 305,

         Crushed PCC pavement meeting the requirements of Materials I.M. 210, or

         Uniformly blended combinations of these materials.

 

4121.02 GRADATION.

 

A. Crushed material: meet the requirements for Gradation No. 12a of the Aggregate Gradation Table, Article 4109.02.

 

B. Gravel: meet the requirements for Gradation No. 12b of the Aggregate Gradation Table, Article 4109.02.

 

4121.03 QUALITY.

The requirements of Table 4121.03-1 apply to the individual virgin aggregates before combining:

 

Table 4121.03-1: Coarse Aggregate Quality (Virgin Material)

Coarse Aggregate Quality

Maximum Percent Allowed

Test Method

Abrasion

50

AASHTO T 96

Alumina(a)

1.5

Office of Materials Test Method No. Iowa 222

A Freeze

25

Office of Materials Test Method No. Iowa 211, Method A

(a) If the Alumina value fails, determine the A Freeze value for specification compliance. Office of Materials Test Method No. Iowa 222 does not apply to gravel.