Crushed stone or natural sand and gravel. If approved by the Engineer, manufactured sand may be substituted in applications where drainage is not a purpose for use of the granular material.
Meet the requirements for Gradation No. 32 of the Aggregate Gradation Table, Article 4109.02, except when used as backfill material under flowable mortar or as floodable backfill material.
For crushed stone, meet the requirements of Table 4133.03-1:
Table 4133.03-1: Aggregate Quality (Granular Backfill Material)
|
Coarse Aggregate Quality |
Maximum Percent Allowed |
Test Method |
|
Abrasion |
55 |
AASHTO T 96 |
|
C Freeze |
20 |
Iowa DOT Materials Laboratory Test Method No. 211, Method C |
|
Total of Abrasion & C Freeze |
65 |
--- |
|
Clay Lumps and Friable Particles |
4 |
Use one of the following:
A. Natural sand complying with the requirements for Gradation No. 1 of the Aggregate Gradation Table, Article 4109.02, with a maximum of 4% passing the No. 200 sieve.
B. Porous Backfill Material complying with Section 4131.
C. Floodable Backfill Material complying with Section 4134.
D. Granular Subbase Material complying with Section 4121.