Section 4127.  Aggregate for Hot Mix Asphalt

                                   

4127.01     DESCRIPTION.

 

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 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.

 

B.    If a gravel aggregate has less than 5% retained on the No. 4 sieve (6 mm), the Engineer may replace the requirements of Table 4127.02-1 with the requirements of Article 4127.03.

 

4127.02     COARSE AGGREGATE.

Meet the requirements of Table 4127.02-1:

 

Table 4127.02-1: Coarse Aggregate Quality (Hot Mix Asphalt)

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

Office of Materials Test Method No. Iowa 201

Alumina(a)

0.7

1.5

2.5

Office of Materials Test Method No. Iowa 222

A Freeze

10

25

45

Office of Materials Test Method No. Iowa 211, Method A

C Freeze

N/A

10

10

Office of Materials Test Method No. Iowa 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

Office of Materials Test Method No. Iowa 215

(a)   If the Alumina value fails, determine the A Freeze value for specification compliance.  Office of Materials Test Method No. Iowa 222 does not apply to gravel.

 

4127.03     FINE AGGREGATE.

 

A.    Natural sand containing no more than 0.01% organic matter when tested using Iowa Test Method 215. A gradation for wearing course mixture of no 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.

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:

 

Table 4127.04: Maximum Shale Allowed

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.