Section 4125.  Aggregate for Bituminous Sealcoat

 

4125.01     DESCRIPTION.

Crushed stone, gravel, or sand.

·         Must be washed.

·         Crushed aggregate is required for primary and interstate roadways and may be specified for other projects.

·         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.

 

4125.02     GRADATION.

Meet aggregate gradation requirements for the gradation number specified in Table 4125.02-1. 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

19

Screened Gravel

20

3/8 inch Crushed Gravel or Stone

21(a)

Sand Cover Aggregate

1(b)

(a)   1/2 inch size may be used when 3/8 inch size is specified except for Primary Road applications.

(b)   For a crushed stone product allow up to 4% passing the No. 200 sieve.

 

4125.03     QUALITY.

·         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 4125.03-1:

 

4125.03-1: Aggregate Quality (Bituminous Sealcoat)

Aggregate Quality

Maximum Percent Allowed

Test Method

Abrasion

40

AASHTO T 96

C Freeze

10

Office of Materials Test Method No. Iowa 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