Section 4115.  Coarse Aggregate for Portland Cement Concrete

 

4115.01     DESCRIPTION.

Gravel or crushed stone particles meeting one of the aggregate durability classes listed below. Acquire aggregates from an approved source meeting the requirements of Materials I.M. 409. Unless stated otherwise on the source approval, coarse aggregate for Portland Cement Concrete shall be washed with sufficient agitation to cause material coatings to be separated and removed.

 

A.    Class 2 Durability.

No deterioration of pavements of non-Interstate segments of the road system after 15 years and only minimal deterioration in pavements after 20 years of age.

 

B.    Class 3 Durability.

No deterioration of pavements of non-Interstate segments of the road system after 20 years of age and less than 5% deterioration of the joints after 25 years.

 

C.    Class 3i Durability.

No deterioration of pavements of the Interstate Road System after 30 years of service and less than 5% deterioration of the joints after 35 years.

 

4115.02     QUALITY.

Meet the requirements of Tables 4115.02-1 and 4115.02-2:

 

Table 4115.02-1: Aggregate Quality

Aggregate Quality

Maximum Percent Allowed

Test Method

Abrasion (Cr. Stone)

50

AASHTO T 96

Abrasion (Gravel)

35

(may be increased by 0.1% for each 1% of particles with at least one fractured face)

AASHTO T 96

Alumina(a)

0.5

Iowa DOT Materials Laboratory Test Method No. 222

A Freeze

6

Iowa DOT Materials Laboratory Test Method No. 211, Method A

Clay Lumps and Friable Particles

0.5

Materials I.M. 368

(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.

 

Table 4115.02-2: Maximum Permissible Amounts of Objectionable Materials

Objectionable Materials.

Maximum Percent Allowed

Test Method

Coal and carbonaceous shale

0.5

Materials I.M. 372

Total of all shale, similar objectionable materials, and coal combined

1.0

Materials I.M. 372

Organic Materials, except coal

0.01

Iowa DOT Materials Laboratory Test Method No. 215

Unsound chert particles retained on 3/8 inch sieve (Nonstructural concrete)

3.0

Materials I.M. 372

Unsound chert particles retained on 3/8 inch sieve (Structural concrete)

2.0

Materials I.M. 372

Note: Chert particle which break into three or more pieces when subjected to the freezing and thawing test will be considered unsound.

 

        Chert in aggregate produced from limestone sources is defined as unsound when any of the fractions of the crushed or uncrushed chert do not meet the soundness requirements.

 

4115.03     gradation.

Meet the requirements of Article 4109.02 and Table 4115.03-1:

 

Table 4115.03-1: Aggregate Gradations

Mix Class

(Materials I.M. 529)

Mix Number

(Materials I.M. 529)

Gradation Numbers

(Article 4109.02)

D

57, 57-6

3 or 5

A, B, C

2 to 8, V47B

3, 4, or 5

M

4

3, 4, or 5

A, B, C, M

V

7

 

 

4115.04     aggregate use durability requirements.

 

A.    Meet the requirements of Table 4115.04-1:

 

Table 4115.04-1: Aggregate Use Durability Requirements

Specification Section Number

Minimum Durability Class Required

Use

3i

3

2

2122, 2201, 2212, 2213, 2301, 2302, 2310, 2529, 2530

Interstate System

Primary System

Other

 

X*

 

 

 

X*

 

 

 

 

 

X

PCC Paved Shoulders, Base, Base Repair, Base Widening PCC Pavement, Widening, PCC Overlay, Finish Patches, and Bridge Approaches

2403

 

 

X

Structural Concrete

2406 (See 2403)

 

 

X

Concrete Structures

2407

 

 

X

Precast Units

2407, 2501

 

X

 

Prestressed Units, Concrete Piles

2412 (See 2403)

Interstate and Primary System Other

 

X

X

Concrete Bridge Decks

2413 (See 2413.02, D, 1)

 

 

X

 

Bridge Deck Surfacing, Repair, & Overlay

2414 (See 2403)

 

 

X

Concrete Railings

2415 (See 2403)

 

 

X

Concrete Box, Arch, & Circular Culverts

2416 (See 4145)

 

 

X

Rigid Pipe Culverts

2424

 

 

X

Shotcrete

2503 (See 2403)

 

 

X

Storm Sewers (Catch Basins, Intakes, & Utility Access)

2505 (See 2403)

 

 

X

Guardrails (Concrete End Anchorage)

2511, 2515 (See 2403)

 

 

X

PCC Sidewalks, Paved Driveways

2512 (See 2403)

 

 

X

PCC Curb & Gutter

2513 (See 2403)

 

 

X

Concrete Barrier

2516 (See 2403)

 

 

X

Concrete Walls and Steps

2517

Primary System

Other

 

 

X

 

 

X

Railroad Approach Sections

2522 (See 2403)

 

X

Tower Lighting (Concrete Footings & Foundations)

2523 (See 2403)

 

X

Highway Lighting (Concrete Footings & Foundations)

2524 (See 2403)

 

X

Highway Signing (Concrete Footings & Foundations)

2525 (See 2403)

 

X

Traffic Signals (Concrete Footings & Foundations)

*       For patches and PCC base repair, Class 2 durability or better aggregate will be required if the existing pavement was constructed of Class 2 or lower durability aggregate. If the existing pavement was constructed of Class 3 or Class 3i durability aggregate, use Class 3 aggregate or better and Class 3i aggregate, respectively, in the repair.

 

B.    Use crushed stone coarse aggregate for:

·         Aesthetic concrete cast with form liners or rustication. This includes Mechanically Stabilized Earth (MSE) walls and noise walls.

·         Concrete receiving color sealer or texture treatments.

·         Concrete for precast box culverts that are to receive color sealer.

 

4115.05     cOARSE aggregate for bridge deck surfacing, repair, and overlay.

Acquire from a Class 3 durability or better source meeting the following requirements:

 

A.    Quality.

Meet the requirements of Tables 4115.05-1 and 4115.05-2:

 

Table 4115.05-1: Aggregate Quality

Aggregate Quality

Maximum Percent Allowed

Test Method

Abrasion

40

AASHTO T 96

Alumina(a)

0.5 

Iowa DOT Materials Laboratory Test Method No. 222

A Freeze

6

Iowa DOT Materials Laboratory Test Method No. 211, Method A

Absorption

2.5

Iowa DOT Materials Laboratory Test Method No. 201

(a)   If the Alumina value fails, determined the A Freeze value for specification compliance. Iowa DOT Materials Laboratory Test Method No. 222 does not apply to gravels.

 

       Table 4115.05-2: Maximum Permissible Amounts of Objectionable Material

Objectionable Materials

Maximum Percent Allowed

Test Method

Unsound chert particles retained on No. 4 sieve

0.5

Materials I.M. 372

Total of all unsound chert, shale, coal, and iron combined

1.0

Materials I.M. 372

Organic Materials, except coal

0.01

Iowa DOT Materials Laboratory Test Method No. 215

Note:  Unsound chert particles are defined in Article 4115.02.

 

B.    Gradation.

Meet the gradation requirements for Gradation No. 6 of the Aggregate Gradation Table, Article 4109.02.