Section 4127. Aggregate for Hot Mix Asphalt.
4127.01 DESCRIPTION.
Crushed stone, gravel, slag, sand, and filler from an approved source. Crushed gravel
may be used to satisfy crushed particle and Friction Type 3 requirements for HMA 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 (6 mm) larger than the sieve size that 100% of the
gravel will pass after crushing.
If a gravel aggregate has less than 5% retained on the No. 4 sieve (6 mm), the Engineer may replace the requirements of Table 4127.02 with the requirements of Article 4127.03.
4127.02 COARSE AGGREGATE.
Meet the following requirements:
TABLE 4127.02 Coarse Aggregate Quality Type A Maximum % Type B Maximum % Test Method Primary Other Abrasion 45 45 45 AASHTO T 96 Absorption 6.0 6.0 6.0 Iowa DOT Materials Laboratory Test Method 201 Alumina (a) 0.7 1.5 2.5 Iowa DOT Materials Laboratory Test Method 222 A Freeze 10 25 45 Iowa DOT Materials Laboratory Test Method 211, Method A C Freeze N/A 10 10 Iowa DOT Materials Laboratory Test Method 211, Method C Clay Lumps/Friable Particles 0.5 N/A N/A Materials I.M. 368 Organic Material 0.01 0.01 0.01 Iowa DOT Materials Laboratory Test Method 215 (a) If the Alumina value fails, the A Freeze value shall be determined for specification compliance. Iowa DOT Materials Laboratory Test Method 222 does not apply to gravel.
4127.03 FINE AGGREGATE.
Use:
A. Natural sand. A gradation for wearing course mixture shall not have more than 50% retained between two consecutive standard sieves below the No. 4 (4.75 mm).B. Crushed gravel or stone processed from coarse aggregate meeting the requirements of Article 4127.02.
Fine aggregate shall contain no more than 0.01% organic matter when tested using Materials I.M. 215.
4127.04 COMBINED AGGREGATES.
Use aggregate, which does not contain adherent films of clay or other matter, which will prevent
coating of particles with asphalt binder. Meet gradations of
Materials I.M. 510.
Maximum shale allowed in the fine portion of the combined materials:
TABLE 4127.04
Aggregate Type Maximum Percent Allowed Test Method Type A 2.0 Materials I.M. 344 Type B 5.0 Materials I.M. 344
4127.05 MINERAL FILLER.
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.