Section 4127.  Aggregate for Flexible Paving Mixtures

                                   

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 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.

 

4127.02     COARSE AGGREGATE.

Meet the requirements of Table 4127.02-1:

 

Table 4127.02-1: Coarse Aggregate Quality (Flexible Paving Mixtues)

Coarse Aggregate Quality

Type A Maximum %

Type B

Maximum %

Test Method

Primary

Other

Abrasion

45

45

45

AASHTO T 96

Absorption(a)

6.0

6.0

6.0

Iowa DOT Materials Laboratory Test Method No. 201

Alumina(b)

1.0

1.5

2.5

Iowa DOT Materials Laboratory Test Method No. 222

A Freeze

15

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

2.0

N/A

N/A

Materials I.M. 368

Organic Material

0.01

0.01

0.01

Iowa DOT Materials Laboratory Test Method No. 215

(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.

 

4127.03     FINE AGGREGATE.

 

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:

 

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.