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.