Type s asphalt concrete, quality assurance and acceptance procedures




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SECTION 331

TYPE S ASPHALT CONCRETE, QUALITY

ASSURANCE AND ACCEPTANCE PROCEDURES
331-1 Description.

331-1.1 General: Construct a Type S Asphalt Concrete course (using the Quality Assurance acceptance system) using the type of mixture specified in the Contract, or when offered as alternates, as selected. If offered as alternates, meet the layer thickness criteria specified in 331-1.2. Type S mixes are identified as Type S-I, Type S-II, or Type S-III. The composition and physical test properties for all mixes including Type S Asphalt Concrete are shown in Tables 331-1 and 331-2. This Section establishes Acceptance Procedures for materials and work performed under Sections 280, 290, 331, 332, 333, 335, and 337.

Where Type S Asphalt Concrete is specified in the Contract, if approved by the Engineer, the equivalent fine Type SP Asphalt Concrete mixture (Traffic Level C) meeting the requirements of Section 334 may be selected as an alternate at no additional cost to the Department. The equivalent mixes are as follows:

Type S-I Type SP-12.5

Type S-II Type SP-19.0

Type S-III Type SP-9.5

Meet the requirements for plant and equipment specified in Section 320. Meet the general construction requirements specified in Section 330.




Table 331-1

Bituminous Concrete Mixtures

(Gradation Design Range)


Type

Total Aggregate Passing Sieves1

3/4 inch

[19.0 mm]



1/2 inch

[12.5 mm]



3/8 inch

[9.5 mm]


No. 4

[4.75 mm]



No. 10

[2.0 mm]


No. 40

[425 μm]


No. 80

[180 μm]


No. 200

[75 μm]


S-I5

100

88-98

75-93

47-75

31-53

19-35

7-21

2-6

S-II2

83-98

71-87

62-78

47-63

33-49

19-35

9-18

2-6

S-III5




100

88-98

60-90

40-70

20-45

10-30

2-6

Type II




100

90-100

80-100

55-90







2-12

Type III




100

80-100

65-100

40-75

20-45

10-30

2-10

SAHM




100
















0-12

ABC-1




100
















0-12

ABC-2




100







55-90







0-12

ABC-33

70-100







30-70

20-60

10-40




2-10

FC-24




100

85-100

10-40

4-12







2-5

FC-35




100

88-98

60-90

40-70

20-45

10-30

2-6

1 In inches [mm] or sieves [μm].

2 100% passing 1 1/4 inch [31.5 mm] sieve and 94 to 100% passing 1 inch [25.0 mm] sieve.

3 100% passing 1 1/2 inch [37.5 mm] sieve.

4 The Engineer may increase the design range for the No. 10 [2.00 mm] sieve for lightweight aggregates.

5 The Engineer may retain up to 1% on the maximum sieve size.




Table 331-2 Non SI Units

Marshall Design Properties For Bituminous Concrete Mixes



Mix Type

Minimum Marshall Stability

(lbs.)


Flow**

(0.01 in.)



Minimum VMA (%)

Air Voids (%)

Minimum Effective Asphalt Content (%)

VFA Voids Filled with Asphalt (%)

S-I

1,500*

8-13

14.5

4-5

***

65-75

S-II

1,500*

8-13

13.5

4-5

***

65-75

S-III

1,500*

8-13

15.5

4-6

***

65-75

Type II

500-750

7-15

18

5-16

6.0

-

Type III

750-1,000

7-15

15

5-12

5.5

-

SAHM

300-500

7-15

15

5-16

6.0

-

ABC-1

500

7-15

15

5-16

6.0

-

ABC-2

750

7-15

15

5-14

5.5

-

ABC-3

1,000

8-13

14

4-7

***

65-78

FC-2

-

-

-

-

-

-

FC-3

1,500

8-13

15.5

4-6

***

65-75

*The minimum Marshall Stability for Type S mixes used on limited access facilities (Interstate, Turnpike, and Expressways) shall be 1,800 lbs.

**The maximum Flow value during production shall not exceed one point more than shown in the Table.

***The ratio of the percentage by weight of total aggregate passing the No. 200 sieve to the effective asphalt content expressed as a percentage by weight of total mix shall be in the range of 0.6 to 1.2.





Table 331-2 SI Units

Marshall Design Properties For Bituminous Concrete Mixes



Mix Type

Minimum Marshall Stability (kN)

Flow** (mm)

Minimum VMA (%)

Air Voids (%)

Minimum Effective Asphalt Content (%)

VFA Voids Filled with Asphalt (%)

S-I

6.7*

2.0-3.3

14.5

4-5

***

65-75

S-II

6.7*

2.0-3.3

13.5

4-5

***

65-75

S-III

6.7*

2.0-3.3

15.5

4-6

***

65-75

Type II

2.2-3.3

1.8-3.8

18

5-16

6.0

-

Type III

3.3-4.4

1.8-3.8

15

5-12

5.5

-

SAHM

1.3-2.2

1.8-3.8

15

5-16

6.0

-

ABC-1

2.2

1.8-3.8

15

5-16

6.0

-

ABC-2

3.3

1.8-3.8

15

5-14

5.5

-

ABC-3

4.4

2.0-3.3

14

4-7

***

65-78

FC-2

-

-

-

-

-

-

FC-3

6.7

2.0-3.3

15.5

4-6

***

65-75

*The minimum Marshall Stability for Type S mixes used on limited access facilities (Interstate, Turnpike, and Expressways) shall be 8.0 kN.

**The maximum Flow value during production shall not exceed 0.25 mm more than shown in the Table.

***The ratio of the percentage by weight of total aggregate passing the 75μm sieve to the effective asphalt content expressed as a percentage by weight of total mix shall be in the range of 0.6 to 1.2.

The Engineer will accept the work on a LOT to LOT basis in accordance with the applicable requirements of Sections 5, 6, and 9. The size of the LOT will be as specified in 331-6 for the bituminous mixture produced at the plant and as stipulated in 331-7 for the material placed on the roadway.



331-1.2 Layer Thicknesses:

331-1.2.1 Structural Layers: The allowable layer thicknesses for Type S Asphalt Concrete mixtures used in structural and overbuild applications is as follows:

Type S-III 3/4 – 1 1/4 inches [20 – 30 mm]

Type S-I 1 1/4 – 2 1/2 inches [30 – 60 mm]

Type S-II 2 – 2 3/4 inches [50 – 70 mm]

In addition to the minimum and maximum thickness requirements, the following restrictions are placed on Type S mixtures when used as a structural course:

Type S-III – Limited to the final (top) structural layer, one layer only.

Type S-I – May not be used in the first layer of courses over 3 1/2 inches [90 mm] thick, nor in the first layer of courses over 2 3/4 inches [70 mm] thick on limited access facilities.

Type S-II – May not be used in the final (top) structural layer.



331-1.2.2 Additional Requirements: The following requirements also apply to Type S Asphalt Concrete mixtures:

1. A minimum 1 1/2 inch [40 mm] initial lift is required over an Asphalt Rubber Membrane Interlayer (ARMI).

2. When construction includes the paving of adjacent shoulders (5 feet [1.5 m] wide), the layer thickness for the upper pavement layer and shoulder shall be the same and paved in a single pass, unless shown differently in the plans.

3. All overbuild layers shall be Type S asphalt concrete. Use the minimum and maximum layer thicknesses as specified in 331-1.2.1 unless shown differently in the plans. On variable thickness overbuild layers, the minimum allowable thickness may be reduced by 1/2 inch [13 mm], and the maximum allowable thickness may be increased 1/2 inch [13 mm], unless shown differently in the plans. Other variations from these thicknesses must be approved by the Engineer.


331-2 Materials.

331-2.1 General Requirements: Meet the material requirements specified in Division III. Specific references are as follows:

Superpave PG Asphalt Binder or Recycling Agent 916-1, 916-2

Mineral Filler 917-1, 917-2

Coarse Aggregate, Stone, Slag or Crushed Gravel Section 901

Fine Aggegate Section 902
Asphalt concrete mixes containing crushed gravel as coarse aggregate component must show no potential for stripping during laboratory testing for mix design verification.

Crushed Reclaimed Portland Cement Concrete Pavement may be used as a coarse aggregate or screenings component subject to meeting all applicable specifications.



331-2.2 Specific Requirements:

331-2.2.1 Condition of Aggregate: Use clean aggregate containing no deleterious substances. Do not use coarse or fine aggregate which contains more than 0.5% of phosphate.

331-2.2.2 Fine Aggregate and Mineral Filler: In laboratory tests, and for the purpose of proportioning the paving mixture, consider all material passing the No. 10 [2.00 mm] sieve and retained on the No. 200 [75 μm] sieve as fine aggregate, and the material passing the No. 200 [75 μm] sieve as mineral filler.

331-2.2.3 Screenings: Do not use any screenings in the combination of aggregates containing more than 15% of material passing the No. 200 [75 μm] sieve. When two screenings are blended to produce the screening component of the aggregate, one of such screenings may contain up to 18% of material passing the No. 200 [75 μm] sieve, as long as the combination of the two does not contain over 15% material passing the No. 200 [75 μm] sieve. Screenings may be washed to meet these requirements.

331-2.2.4 Use of Reclaimed Asphalt Pavement (RAP): Subject to certain requirements, Reclaimed Asphalt Pavement (RAP) may be used as a component material of the asphalt mixture. Where the material is recovered from a FDOT project, the Composition of Existing pavement may be available on the Department’s web site. The URL for obtaining this information, if available, is: www11.myflorida.com/statematerialsoffice/Bituminous/CentralBitLab/AsphaltCompositions/Compositions.htm

RAP may be used as a component material of the bituminous mixture subject to the following:

1. Assume responsibility for the design of asphalt mixes which incorporate RAP as a component part.

2. Do not allow RAP to exceed 60% by weight of total aggregates for Asphalt Base Courses nor more than 50% by weight of total aggregates for Structural and Leveling Courses. Do not use RAP in Friction Courses.

3. Mount a grizzly or grid with openings of a sufficient size to prevent clogging of the cold feed over the RAP cold bin.

Use a grizzly or grid over the RAP cold bin, in-line roller crusher, screen, or other suitable means to prevent oversized RAP material from showing up in the completed recycled mixture.

If oversized RAP material appears in the completed recycled mix, cease plant operations and take appropriate corrective action.

4. Ensure that the RAP material as stockpiled is reasonably uniform in characteristics and contains no aggregate particles which are soft or conglomerates of fines.

5. Ensure that the RAP has a minimum average asphalt content of 4% by weight of total mix. The Department reserves the right to sample the stockpile in order that this requirement is met.

When material milled from the project is used as a component of the asphalt mixture and a Composition of Existing Pavement is known, use the following procedures for obtaining representative samples for the mix design:

1. Cut ten 6-inch [150 mm] cores in area(s) approved by the Engineer. Fill the core holes immediately prior to opening to traffic.

2. Representative samples may also be obtained by milling the existing pavement to the full depth shown on the plans for pavement removal for a length of approximately 200 feet [60 m]. Immediately replace the pavement removed with the specified mix in the Contract.

3. Submit a request in writing to the Engineer for any variance from the above outlined methods of obtaining samples for mix designs.

When the RAP to be used as a component in a mix design is stockpiled from a previous DOT project and the Composition of Existing Pavement is known, design the mix and submit to the Department for verification.

When the composition of stockpiled RAP to be used as a component in a mix design is not known, design the mix as follows:

1. Submit a bag of RAP, composed of samples from several locations in the stockpile(s), to the Department at least four weeks prior to the planned start of mix design. The Engineer will run viscosities on the reclaimed asphalt pavement and furnish the information to the Contractor.

2. Run a minimum of six extraction gradation analyses of the RAP. Take the samples at random locations around the stockpile(s).

3. Request the Engineer to make a visual inspection of the stockpile(s) of RAP. Based on visual inspection, the Engineer will determine the suitability of the stockpiled materials.

4. When the proposed mix design is submitted to the Department for verification, submit the data from the extraction gradation analyses required above.

331-2.2.5 Binder for Mixes with RAP: Use a PG 67-22 where RAP is less than 20% by weight of total aggregate; use a PG 64-22 where RAP is 20% or greater but less than 30% by weight of total aggregate; use appropriate recycle agent where RAP is 30% or greater.

The Engineer reserves the right to change binder type and grade at design based on the characteristics of the RAP binder, and reserves the right to request reasonable changes during the production based on the requirements of 331-4.4.4.



331-2.2.6 Use of Recycled Crushed Glass: Recycled crushed glass may be used as a component of the bituminous mixture subject to the following:

1. Consider the recycled crushed glass a local material and meet all requirements specified in 902-6.

2. The percentage of recycled crushed glass in any bituminous mixture does not exceed 15% of the total aggregate weight.

3. The asphalt binder used with mixtures containing recycled crushed glass contains 0.5% anti-stripping agent from an approved source. The addition of the specified amount of anti-stripping agent must be certified by the supplier.

4. Test bituminous mixtures containing recycled crushed glass in accordance with AASHTO T 283 as part of the mix design approval. The minimum tensile strength ratio must not be less than 80%. An increase in the amount of anti-stripping agent may be necessary in order to meet this requirement.

5. Recycled crushed glass must not be used in friction course mixtures nor in structural course mixtures which are to be used as the final wearing course.

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