Section 4127. Aggregate for Flexible Paving Mixtures
A. Crushed stone, gravel, slag, sand, and filler from
an approved source. Crushed gravel may be used to satisfy crushed particle and
friction requirements for flexible paving mixtures. Produce crushed gravel as a
separate operation by crushing the portion of a gravel aggregate retained on a
screen at least 1/4 inch larger than the sieve size that 100% of the gravel
will pass after crushing.
B. If a gravel aggregate has 100%
passing the 3/8 inch sieve, the Engineer may replace the requirements of Table
4127.02-1 with the requirements of Article 4127.03.
Meet the requirements of Table 4127.02-1:
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Table 4127.02-1: Coarse Aggregate Quality (Flexible Paving Mixtues) |
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|
Coarse Aggregate Quality |
Type A Maximum % |
Type B Maximum % |
Test Method |
|
|
Primary |
Other |
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|
Abrasion |
45 |
45 |
45 |
AASHTO T 96 |
|
Absorption |
6.0 |
6.0 |
6.0 |
Iowa DOT Materials Laboratory Test Method No. 201 |
|
Alumina(a) |
0.7 |
1.5 |
2.5 |
Iowa DOT Materials Laboratory Test Method No. 222 |
|
A Freeze |
10 |
25 |
45 |
Iowa DOT Materials Laboratory Test Method No. 211, Method A |
|
C Freeze |
N/A |
10 |
10 |
Iowa DOT Materials Laboratory Test Method No. 211, Method C |
|
Clay Lumps/Friable Particles |
0.5 |
N/A |
N/A |
|
|
Organic Material |
0.01 |
0.01 |
0.01 |
Iowa DOT Materials Laboratory Test Method No. 215 |
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(a) If the Alumina value fails, determine the A Freeze value for specification compliance. Iowa DOT Materials Laboratory Test Method No. 222 does not apply to gravel. |
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A. Natural sand containing no more than 0.01% organic matter when tested using Iowa DOT Materials Laboratory Test Method No. 215. A gradation for wearing course mixture of no more than 50% retained between two consecutive standard sieves below the No. 4 sieve or gravel aggregate with 100% passing the 3/8 inch sieve meeting these requirements.
B. Crushed gravel or stone processed from coarse aggregate meeting the requirements of Article 4127.02.
4127.04 COMBINED AGGREGATES.
A. Use aggregate, which does not contain adherent films of clay or other matter that will prevent coating of particles with asphalt binder. Meet gradations of Materials I.M. 510.
B. Maximum shale allowed in the fine portion of the combined materials:
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Table 4127.04: Maximum Shale Allowed |
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|
Aggregate Type |
Maximum Percent Allowed |
Test Method |
|
Type A |
2.0 |
|
|
Type B |
5.0 |
|
For fine material added to the mixture, separate from cold feed, meet the requirements for mineral filler in AASHTO M 17, except determine the gradation according to AASHTO T 11.