4131 Porous Backfill Material

Section 4131. Porous Backfill Material.

4131.01 DESCRIPTION.
Gravel of crushed stone.

4131.02 GRADATION.
Meet the requirements of Gradation No. 29 of the Aggregate Gradation Table, Article 4109.02.

4131.03 QUALITY.
No visible clay lumps, friable particles, and clay coatings. Meet the following requirements:

TABLE 4131.03

Aggregate Quality Maximum Percent Allowed Test Method

Abrasion 50 AASHTO T 96

Alumina ^(a) 0.7 Iowa DOT Materials Laboratory Test Method 222

A Freeze 10 Iowa DOT Materials Laboratory Test Method 211, Method A

Shale 5 Materials I.M. 345

(a) If the Alumina value fails, the A Freeze value shall be determined for specification compliance. Iowa DOT Materials Laboratory Test Method 222 does not apply to gravel.

TABLE 4131.03
Aggregate Quality	Maximum Percent Allowed	Test Method
Abrasion	50	AASHTO T 96
Alumina ^(a)	0.7	Iowa DOT Materials Laboratory Test Method 222
A Freeze	10	Iowa DOT Materials Laboratory Test Method 211, Method A
Shale	5	Materials I.M. 345
(a) If the Alumina value fails, the A Freeze value shall be determined for specification compliance. Iowa DOT Materials Laboratory Test Method 222 does not apply to gravel.