4125.01DESCRIPTION
Crushed stone, gravel, or sand. • Must be washed. • Crushed aggregate is required for primary and interstate roadways and may be specified for other projects.
4126.03
•
Aggregate for Polymer-Modified Microsurfacing
Produce crushed gravel as a separate operation by crushing the gravel particles retained on a screen at least 1/4 inch larger than the aggregate size specified.
4125.02GRADATION
Meet aggregate gradation requirements for the gradation number specified in Table
1. Unless specified otherwise, use the 1/2 inch sieve size
Table 4125.02-1: Aggregate Gradation Requirements (Bituminous Sealcoat) Size Gradation No. 1/2 inch Crushed Gravel or Stone
Screened Gravel
3/8 inch Crushed Gravel or Stone
21(a)
Sand Cover Aggregate 1(b)
Road applications.
4125.03QUALITY
• Free from objectionable clay coatings that prevent emulsions from fully coating the aggregate when determined using Materials I.M. 349. • Type 4 or better frictional classification as shown in Materials I.M. T203. • For cover aggregate for bituminous sealcoat, meet the requirements of Table
1: Aggregate Quality (Bituminous Sealcoat)
Aggregate Quality
Maximum Percent Allowed
Test Method
Abrasion
AASHTO T 96
C Freeze
Iowa DOT Materials Laboratory Test Method No. 211, Method C
Shale (+ No. 4 sieve)
5.0
Materials I.M. 372
Shale (+ No. 16 sieve) (Sand cover aggregate)
2.0
Materials I.M. 344