Section 4123. Modified Subbase Material



Aggregate of the following Types:

         Crushed stone,

         Gravels for which 75% 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,

         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 (50 mm) 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 blended and non-blended virgin materials:


Table 4123.03-1: Aggregate Quality (Blended and Non-blended Virgin Materials)

Aggregate Quality

Maximum Percent Allowed

Test Method

Abrasion (a)



C Freeze


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

Alumina (b) (No. 40 (425 μm) material)


Office of Materials Test Method No. Iowa 222

(a)    Virgin material with Al2O3 not exceeding 0.7 (+4) or A-freeze not exceeding 10 may have an abrasion maximum of 55.

(b)    For gravel or gravel/non-gravel blend, have a plasticity index not exceeding 7 for each source.


B. Acquire gravel or gravel/non-gravel blend products from a gravel source with a plasticity index not exceeding 7.