Section 4123.  Modified Subbase Material

4123.01     DESCRIPTION.

Aggregate of the following Types:

· Crushed stone,

· Gravels for which 75% or more of the particles retained on the 3/8 inch sieve have at least one fractured face as defined in Materials I.M. 305,

· Recycled pavements meeting Materials I.M. 210, or

· Uniformly blended combinations of these materials with a maximum of 50% RAP.

4123.02     GRADATION.

A.    Meet the requirements for Gradation No. 14 of the Aggregate Gradation Table, Article 4109.02.

B.    Process RAP to pass the 2 inch sieve.

C.    Uncrushed gravel and/or sand may be uniformly blended with crushed recycled pavement or crushed stone at a maximum rate of 50% to meet gradation requirements.

4123.03     QUALITY.

A.    The requirements of Table 4123.03-1 apply to virgin materials:

Table 4123.03-1: Aggregate Quality
Aggregate Quality	Maximum Percent Allowed	Test Method
Abrasion	50	AASHTO T 96
C Freeze	15	Iowa DOT Materials Laboratory Test Method No. 211, Method C
Alumina ^(a) (minus No. 40 material)	4.7	Iowa DOT Materials Laboratory Test Method No. 222
(a) The alumina requirement does not apply to gravel and recycled PCC.

B. The requirements of Table 4123.03-1 apply to recycled PCC when the aggregate source is unknown as outlined in Materials I.M. 210.