Section 4127. Aggregate for Flexible Paving Mixtures
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.
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 |
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Primary |
Other |
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Abrasion |
45 |
45 |
45 |
AASHTO T 96 |
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Absorption(a) |
6.0 |
6.0 |
6.0 |
Iowa DOT Materials Laboratory Test Method No. 201 |
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Alumina(b) |
1.0 |
1.5 |
2.5 |
Iowa DOT Materials Laboratory Test Method No. 222 |
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A Freeze |
15 |
25 |
45 |
Iowa DOT Materials Laboratory Test Method No. 211, Method A |
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C Freeze |
N/A |
10 |
10 |
Iowa DOT Materials Laboratory Test Method No. 211, Method C |
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Clay Lumps/Friable Particles |
2.0 |
N/A |
N/A |
Materials I.M. 368 |
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Organic Material |
0.01 |
0.01 |
0.01 |
Iowa DOT Materials Laboratory Test Method No. 215 |
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(a) When a coarse aggregate for use in asphalt fails absorption using Iowa DOT Materials Laboratory Test Method No. 201; absorption determined by Materials I.M. 380 (Vacuum-saturated specific gravity & absorption) will be used. (b) 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 meeting the requirements of Table 4127.03-1. 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.
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Table 4127.03-1: Fine Aggregate Quality (Flexible Paving Mixtures) |
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Fine Aggregate Quality |
Type A Maximum % |
Type B Maximum % |
Test Method |
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Organic Matter |
0.01 |
0.01 |
Iowa DOT Materials Laboratory Test Method No. 215 |
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Clay Lumps/Friable Particles |
1.5 |
3.0 |
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Shale |
2.0 |
5.0 |
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(a) Use Method A for initial test. If Method A fails, Method B may be used. |
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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: Coarse and fine aggregate shall meet quality
requirements of Articles
4127.02 and 4127.03
before combining aggregates.
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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.