4131.01DESCRIPTION
Gravel or crushed stone.
4131.02GRADATION
Meet the requirements of Gradation No. 29 of the Aggregate Gradation Table, Article
4109.02
4131.03QUALITY
No visible clay lumps, friable particles, and clay coatings. Meet the requirements of Table 4131.03-1: Table 4131.03-1: Aggregate Quality (Porous Backfill Material) Aggregate Quality
Maximum Percent Allowed
Test Method
Abrasion
50
AASHTO T 96
Alumina(a, b)
0.7
Iowa DOT Materials Laboratory Test Method No. 222
A Freeze
Iowa DOT Materials Laboratory Test Method No. 211, Method A
Shale Materials I.M. 345
(a)If the Alumina value passes, the A-Freeze is not needed for specification
compliance. If the Alumina value fails, determine the A Freeze value for specification compliance.
(b)Alumina does not apply to gravel.
Source: Iowa Standard Specifications for Highway and Bridge Construction, 2023 Edition. Pages 1097–1097 of 1,288.