Section 4131. Porous Backfill Material

4131.01  DESCRIPTION.

Gravel or crushed stone.

4131.02  GRADATION.

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

4131.03  QUALITY.

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	10	Iowa DOT Materials Laboratory Test Method No. 211, Method A
Shale	5	Materials I.M. 345
Clay Lumps and Friable Particles	2.0	Materials I.M. 368

(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.