Section 4125. Aggregate for Bituminous Sealcoat
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.
Meet aggregate gradation requirements for the gradation number specified in Table 4125.02-1. Unless specified otherwise, use the 1/2 inch sieve size.
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Table 4125.02-1: Aggregate Gradation Requirements (Bituminous Sealcoat) |
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Size |
Gradation No. |
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1/2 inch Crushed Gravel or Stone |
19 |
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Screened Gravel |
20 |
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3/8 inch Crushed Gravel or Stone |
21(a) |
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Sand Cover Aggregate |
1(b) |
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(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. |
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· 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:
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4125.03-1: Aggregate Quality (Bituminous Sealcoat) |
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Aggregate Quality |
Maximum Percent Allowed |
Test Method |
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Abrasion |
40 |
AASHTO T 96 |
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C Freeze |
10 |
Office of Materials Test Method No. Iowa 211, Method C |
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Shale (+ No. 4 sieve) |
5.0 |
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Shale (+ No. 16 sieve) (Sand cover aggregate) |
2.0 |
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