4125Aggregate for Bituminous Sealcoat

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