Section 4115. Coarse Aggregate for Portland Cement Concrete
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.
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.
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.
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.
Meet the requirements of Tables 4115.02-1 and 4115.02-2 and Section 4109:
|
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, b) |
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 |
|
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(a) If the Alumina value passes, the A-Freeze is not needed for specification compliance. If the Alumina value fails, determine the A Freeze value for specification compliance. (b) Alumina does not apply to gravel. |
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Table 4115.02-2: Maximum Permissible Amounts of Objectionable Materials |
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Objectionable Materials. |
Maximum Percent Allowed |
Test Method |
|
Coal and carbonaceous shale |
0.5 |
|
|
Total of all shale, similar objectionable materials, and coal combined |
1.0 |
|
|
Organic Materials, except coal |
0.01 |
Iowa DOT Materials Laboratory Test Method No. 215 |
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Unsound chert particles retained on 3/8 inch sieve (Nonstructural concrete) |
3.0 |
|
|
Unsound chert particles retained on 3/8 inch sieve (Structural concrete) |
2.0 |
|
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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. |
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Meet the requirements of Article 4109.02 and Table 4115.03-1:
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Table 4115.03-1: Aggregate Gradations |
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|
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:
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Table 4115.04-1: Aggregate Use Durability Requirements |
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Specification Section Number |
Minimum Durability Class Required |
Use |
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|
3i |
3 |
2 |
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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 |
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|
X |
Structural Concrete |
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|
|
X |
Concrete Structures |
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|
X |
Precast Units |
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|
X |
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Prestressed Units, Concrete Piles |
|
|
Interstate and Primary System Other |
|
X |
X |
Concrete Bridge Decks |
|
2413 (See 2413.02, D, 1) |
|
X |
|
Bridge Deck Surfacing, Repair, & Overlay |
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|
|
X |
Concrete Railings |
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|
|
X |
Concrete Box, Arch, & Circular Culverts |
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|
X |
Rigid Pipe Culverts |
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|
X |
Shotcrete |
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|
X |
Storm Sewers (Catch Basins, Intakes, & Utility Access) |
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|
X |
Guardrails (Concrete End Anchorage) |
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|
X |
PCC Sidewalks, Paved Driveways |
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|
|
X |
PCC Curb & Gutter |
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|
|
X |
Concrete Barrier |
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|
|
X |
Concrete Walls and Steps |
|
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Primary System Other |
|
X
|
X |
Railroad Approach Sections |
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|
X |
Tower Lighting (Concrete Footings & Foundations) |
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|
X |
Highway Lighting (Concrete Footings & Foundations) |
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|
X |
Highway Signing (Concrete Footings & Foundations) |
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X |
Traffic Signals (Concrete Footings & Foundations) |
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* 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. |
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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:
Meet the requirements of Tables 4115.05-1 and 4115.05-2:
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Table 4115.05-2: Maximum Permissible Amounts of Objectionable Material |
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|
Objectionable Materials |
Maximum Percent Allowed |
Test Method |
|
Unsound chert particles retained on No. 4 sieve |
0.5 |
|
|
Total of all unsound chert, shale, coal, and iron combined |
1.0 |
|
|
Organic Materials, except coal |
0.01 |
Iowa DOT Materials Laboratory Test Method No. 215 |
|
Note: Unsound chert particles are defined in Article 4115.02. |
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Meet the gradation requirements for Gradation No. 6 of the Aggregate Gradation Table, Article 4109.02.