828Hot Mix Asphaltic Concrete Mixtures

828.1General Description

This specification includes the requirements for hot mix asphaltic concrete mixtures, including: • Open-graded surface mixtures (OGFC and PEM) • Stone Matrix Asphalt mixtures (SMA) • Superpave mixtures • Fine-graded (4.75 mm) mixtures 828.1.01 Definitions The Nominal Maximum Sieve Size is one standard sieve size larger than the first sieve to retain more than ten percent of the aggregate, per AASHTO R35. Mixture types in this section are identified according to Nominal Maximum Sieve Size. 828.1.02 Related References

AASHTO R30 AASHTO R35 AASHTO T 321 AASHTO T 112 AASHTO T 209 AASHTO T 305 AASHTO T 312 AASHTO T 245 AASHTO T 324 AASHTO T 340 SOP-36 SOP-2 GDT 1 GDT 56 GDT 63 1528 1528 1528

GDT 66 GDT 114 GDT 115 GDT 123 QPL 1 QPL 2 QPL 7 QPL 26 QPL 41 QPL 77 QPL 81

828.2Materials

Use approved hot mix asphalt concrete mixtures that meet the following requirements: Produce each asphalt mixture according to a Department approved Job Mix Formula and Asphalt Mix Design, see Subsection 400.1 for submittal and approval of Job Mix Formulas. Ensure individual acceptance test results meet the Mixture Control Tolerances specified in the appropriate table below, Subsections 828.2.01 through 828.2.04. Ensure the Engineer approves all materials used to prepare and place the mixtures before incorporating them into the Work. Use only the ingredients listed in the approved Asphalt Mix Design and Job Mix Formula. For virgin aggregates use sources meeting the requirements of Section 802 and are listed in QPL 1 or QPL 2; for mixes in which local sand is permitted, use the approved sand source identified in the mix design. For mixtures containing Reclaimed Asphalt Pavement (RAP), use only RAP from the approved stockpile identified in the mix design. Use asphalt cement meeting the requirements of Section 820, from a source listed in QPL 7. Obtain approved SMA mix designs, Superpave mix designs and 4.75 mm mix designs from a mix design laboratory certified by the Department. Obtain approved mix designs for types PEM and OGFC mixtures from the Department's Office of Materials, which produces and furnishes these mix designs. Ensure all SMA mix designs are designed in accordance with GDT-123 (“Determining the Design Proportions of Stone Matrix Asphalt Mixtures”). Ensure SMA mix designs are verified and approved by the Department prior to use. Ensure Superpave and 4.75 mm mix designs are designed in accordance with SOP-2 ("Control of Superpave Bituminous Mixture Designs") and are approved by the Department as provided therein. Ensure these mixes are designed by a laboratory and technician certified in accordance with SOP-36, ("Certification of Laboratories and Personnel for Design of SMA and Superpave Asphalt Mixtures"). Use only mixtures composed of the aggregate groups and blends indicated in the Proposal and Plans by their pay item designations, defined as follows: 1529 1529 1529

TABLE 1 – AGGREGATE GROUPS Pay Item Designation Allowable Aggregate Groups Group I or II Group I, Group II, or Blend I Group II only Group II only Blend I Either 100% Group II material or a blend of Group I and Group II. Do not use Group I material for more than 60%, by weight, of the total aggregate nor more than 50%, by weight, of the coarse aggregate fraction. For patching or leveling use Group I, Group II, or Blend I. Mix types for patching and leveling are specified in Subsection 400.3.03.B. Include lime (hydrated lime) from an approved source and meeting the requirements of Section 882 in all paving courses except as otherwise provided in the Contract. For a list of approved sources of lime, see QPL 41.

aggregate weight. Ensure mix designs using RAP include lime at a minimum rate equal to 1.00% of the virgin aggregate fraction plus 0.50% of the aggregate in the RAP fraction.

requirements of Section 831, if necessary to meet requirements for mixture properties, and pursuant to an approved mix design. However, the Department will not make additional payment for these materials. For a list of sources of Heat-Stable Anti-Stripping Additives, see QPL 26.

Stable Anti-Stripping Additive meeting the requirements of Section 831 may be substituted for hydrated lime. Ensure the mix gradation is adjusted to replace the lime with an equivalent volume of fines passing the 0.075 mm sieve. Add Heat-Stable Anti-stripping Additive at a minimum rate of 0.5 percent of the asphalt cement portion. Use performance grade PG 64-22 or PG 67-22 asphalt cement in all mix designs and mixtures except as follows:

Binders Selection Guideline for Reclaimed Asphalt Pavement (RAP) Mixtures, AASHTO M323 and laboratory testing results as required in Section 828.2.B for mixtures containing ≥ 25% equivalent binder replacement for RAP/RAS mixtures.

PEM, 9.5 mm and 12.5 mm OGFC, 12.5 mm Superpave, on projects with two-way ADT greater than 25,000; and in all mixtures for which polymer-modified asphalt is specified in the pay item. Use of local sand is restricted as follows:

System. Mixtures with local sand may be used for shoulder construction on these facilities.

production mix.

designs containing local sand may be used on projects with a current ADT not exceeding 4,000 VPD providing that all performance testing meets specified requirements.

except the main line and ramps of the Interstate System.

1530 1530 1530

Ensure local sand contains no more than 7.0% clay by weight and is free of foreign substances, roots, twigs, and other organic matter. Ensure sand is free of clay lumps, as determined by AASHTO T 112, and has a sand equivalent value exceeding 25%, as determined by GDT 63.

Design procedures: For all Superpave and 4.75 mm mixes, ensure conformance with the Superpave System for Volumetric Design (AASHTO T 312 and AASHTO R30), as adapted in SOP-2. Ensure Superpave mixes are designed at a design gyration number (Ndes) of 65 gyrations and initial gyration number (Nini) of 6 gyrations. Ensure 4.75 mm mixes, (Ndes) are designed at 50 gyrations, and (Nini) at 6 gyrations. Open-graded mix designs will be designed by the Department in accordance with GDT 114. In all cases, the procedure for measuring Maximum Specific Gravity (G mm) is AASHTO T 209. In addition to gradation and volumetric analysis, ensure mix designs include the following performance tests, as applicable. Performance Test:

Measurement of Water Permeability of Compacted Asphalt Paving Mixtures. Ensure specimen air voids for this test are 6.0 ±1.0 %. The average permeability of three specimens may not exceed 3.60 ft per day (125 ×10−5cm per sec).

the Office of Materials and Testing due to visible signs of stripping in laboratory fabricated or plant produced asphaltic concrete mixtures, ensure specimen air voids for this test are 7.0 ±1.0% for all mixes excluding Stone Matrix mixes. Ensure specimen air voids for this test are 6.0 ± 1.0% for Stone Matrix mixes. The minimum tensile splitting ratio is 0.80, except a tensile splitting ratio of no less than 0.70 may be acceptable if all individual strength values exceed 100 psi (690 kPa). Ensure average splitting strength of the three conditioned and three controlled samples are not less than 60 psi (415 kPa) for either group. Ensure retention of coating as determined by GDT 56 is not less than 95%.

types except Open-graded Surface Mixes (OGFC and PEM), and Open-graded Crack Relief Interlayer

7.0 ± 1.0% for all mix types and at a testing temperature of 50°C (122°F). Use the testing and acceptance criteria established in Table 2. TABLE 2 – HAMBURG WHEEL TRACKING DEVICE TESTING AND ACCEPTANCE CRITERIA Binder Performance Grade (PG) Mix Type Number of Passes Maximum Rut Depth Stripping Inflection Point PG 64-22 and PG 67-22 4.75 mm, 9.5 mm SP Type I, and 9.5 mm SP Type II 15,000 ≤ 12.5 mm > 15,000 PG 64-22 and PG 67-22 12.5 mm SP, 19 mm SP and 25 mm SP 20,000 ≤ 12.5 mm > 20,000 PG 76-22 All Mix types 20,000 ≤ 12.5 mm > 20,000 Tested specimens shall be inspected for any visible signs of stripping and any mix design’s tested specimens that fail to maintain 95% of asphalt cement coating, as described in GDT 56 section D.2.d, will be required to meet specified requirements for GDT 66 as detailed in 828.2.B.2.b.

AASHTO T 321 or other procedure approved by the Department. 1531 1531 1531

See Subsection 106.03 and Section 400. Ensure individual test results meet the Mixture Control Tolerances listed in Subsections 828.2, 828.2.01 ,828.2.02, 828.2.03, or 828.2.04, whichever applies with the following exception. Ensure field verification results for rutting susceptibility tests performed on laboratory fabricated and/or roadway cores obtained from asphalt plant produced mixtures meet specified requirements for AASHTO T 324 as detailed in Subsection 828.2.B.2.c. All GDOT approved mix designs are required to have full field mix design verifications, using plant produced mixture, sampled by the contractor and submitted to the applicable GDOT laboratory (Central or District) at a minimum of once per two years. Field mix design verification results that fail to comply with performance testing specified in Subsection 828.2.B will require a complete laboratory mix design verification, to be completed by the original mix designer, for continued use of that design. If a mix design has not been produced within two years, a full field mix design verification will be sampled by the contractor and submitted to the applicable

GDOT laboratory (Central or District) on the first Lot produced thereafter. Any mix design that fails to meet

performance test requirements established in Subsection 828.2.B, using laboratory fabricated specimens due to

failing field mix design results, may subject that mix design to invalidation after the field mix design verification results

are confirmed with a second field mix design verification. Field mix design verifications as specified in Section 402,

Section 400, SOP 2 and GSP 21, are not precluded by the requirements specified herein.

See General Provisions 101 through 150.

828.2.01 Open-Graded Surface Mixtures

Produce the mixture according to an approved mix design and Job Mix Formula. Ensure Open-Graded Surface

Mixtures meet the following mixture control tolerances and mix design criteria:

Sieve Size Mixture Control

Tolerance, %

Design Gradation Limits, % Passing

9.5 mm

OGFC 12.5 mm OGFC 12.5 mm PEM

3/4 in. (19 mm) sieve ±0.0 100* 100*

1/2 in. (12.5 mm) sieve ±6.1 100* 85-100 80-100

3/8 in. (9.5 mm) sieve ±5.6 85-100 55-75 35-60

No. 4 (4.75 mm) sieve ±5.7 20-40 15-25 10-25

No. 8 (2.36 mm) sieve ±4.6 5-10 5-10 5-10

No. 200 (75 μm) sieve ±2.0 2-4 2-4 1-4

Range for % AC ±0.4 6.0-7.25 5.75-7.25 5.5-7.0

Class of stone (Section 800) “A” only “A” only “A” only

Drain-down (AASHTO T305), % <0.3 <0.3 <0.3

* Mixture control tolerance is not applicable to this sieve for this mix.

In 12.5 mm and 9.5 mm OGFC and 12.5 mm PEM mixes, use only PG 76-22 asphalt cement

(specified in Section 820).

Ensure all OGFC and PEM mixes include a stabilizing fiber of the type (cellulose or mineral) specified in the

mix design and meeting the requirements of Section 819. Ensure the dosage rate is as specified in the mix

design and sufficient to prevent drain-down exceeding the above tolerance.

See Section 400. 153215321532

828.2.02 Stone Matrix Asphalt Mixtures

Produce the mixture according to an approved mix design and Job Mix Formula. Ensure Stone Matrix Asphalt

mixtures meet the following mixture control tolerances and mix design criteria:

Sieve Size

Mixture

Control

Tolerance

Design Gradation Limits, Percent Passing

9.5 mm SMA 12.5 mm SMA 19 mm SMA

1 in. (25 mm) sieve ±0.0 100*

3/4 in. (19 mm) sieve ±7.0 100* 100* 90-100

1/2 in. (12.5 mm) sieve ±6.1 98-100** 85-100 44-70

3/8 in. (9.5 mm) sieve ±5.6 70-100 50-75 25-60

No. 4 (4.75 mm) sieve ±5.7 28-50 20-28 20-28

No. 8 (2.36) mm sieve ±4.6 15-30 16-24 15-22

No. 50 (300 μm) sieve ±3.8 10-17 10-20 10-20

No. 200 (75 μm) sieve ±2.0 8-13 8-12 8-12

Range for % AC

(Note 1)

±0.4

(Note 2)

6.0-7.5 5.8-7.5 5.5-7.5

Design optimum air voids (%) 3.5 ±0.5 3.5 ±0.5 3.5 ±0.5

% aggregate voids filled with AC (VFA) 70-90 70-90 70-90

Tensile splitting ratio after freeze-thaw cycle

GDT-66

80% 80% 80%

Drain-down (AASHTO T305), % <0.3 <0.3 <0.3

*Mixture control tolerance is not applicable to this sieve for this mix.

**Mixture control tolerance is ± 2.0% for this sieve for 9.5 mm SMA mixes placed at spread rates greater than

135 lb./yd

. For 9.5 mm SMA mixes placed at spread rates of 135 lb./yd or less, 100 % passing is required on

this sieve.

Note 1: Range for % AC is Original Optimum AC (OOAC) at 35 gyrations (Gyratory compactor) or 50 blows

(Marshall compactor) prior to Corrected Optimum AC (COAC) calculation detailed in GDT 123 (Appendix A)

Note 2: Quality Acceptance Test Results for AC content that deviate > ± 0.3% from the approved Job Mix

Formula (JMF) consistently over three lots may subject the mix to a revised AC content on project JMF at the

discretion of the State Materials Engineer based on statistical trend.

Ensure SMA mixtures are compacted at 35 gyrations with the Superpave Gyratory compactor or 50 blows

with the Marshall compactor.

Ensure SMA mixtures contain mineral filler and fiber stabilizing additives and meet the following requirements:

Approved sources of mineral filler are listed in QPL 81.

Use the approved Fiber Stabilizing Additive of the type (cellulose or mineral) specified in the mix design and

meeting the requirements of Section 819. Approved sources of Fiber Stabilizing Additive are listed in QPL 77. 153315331533

The dosage rate will be as specified in the mix design and sufficient to prevent drain-down exceeding the

above tolerance.

See Section 400.

828.2.03 Superpave Asphalt Concrete Mixtures

Produce the mixture according to an approved mix design and Job Mix Formula. Ensure Superpave Asphalt

Concrete mixtures meet the following mixture control tolerances and mix design limits:

Gradation limits for Superpave mixtures are as follows:

Sieve Size

Mixture

Control

Tolerance

Design Gradation Limits, Percent Passing

9.5 mm

Superpave

Type I

9.5 mm

Superpave

Type II

12.5 mm

Superpave

(Note 1)

19 mm

Superpave

25 mm

Superpave

1½ in. (37.5 mm) 100*

1 in. (25.0 mm) ± 8.0 100* 100* 90-100

3/4 in. (19.0 mm) ±8.0** 100* 100* 98-100**** 90-100 55-89**

1/2 in. (12.5 mm) ±6.0*** 98-100**** 98-100**** 90-100 60-89*** 50-70

3/8 in. (9.5 mm) ±5.6 90-100 90-100 70-89 55-75

No. 4 (4.75 mm) ±5.6 65-85 55-75

No. 8 (2.36 mm) ±4.6 48-55 42-47 38-46 32-36 30-36

No. 200 (75 μm) ±2.0 5.0-7.0 5.0-7.0 4.5-7.0 4.0-6.0 3.5-6.0

Range for % AC

(Note 3)

± 0.4

(Note 2)

5.50-7.25 5.25-7.00 5.00-6.25 4.25-5.50 4.00-5.25

* Mixture control tolerance is not applicable to this sieve for this mix.

** Ensure mixture control tolerance is within ± 10.0% for this sieve for 25 mm Superpave.

***Ensure mixture control tolerance is within ± 8.0% for this sieve for 19 mm Superpave.

***Ensure mixture control tolerance is within ± 2.0% for this sieve for 12.5 mm and 9.5 mm mixes.

Note 1: Use PG 76-22 in 12.5 mm Superpave, excluding shoulder construction, on all projects with ADT greater than

25,000 as detailed in the Contract Pay Item.

Note 2: Quality Acceptance Test Results for AC content deviating > ± 0.3 % from the approved Job Mix Formula

of the State Materials Engineer based on statistical trend.

Note 3: Range for % AC is Original Optimum AC (OOAC) at 65 gyrations prior to the Corrected Optimum AC (COAC)

calculation detailed in SOP 2 (Appendix D). 153415341534

Volumetric limits are as follows:

Design Parameter Mix Type Limits

% of Max. Specific Gravity (Gmm) at design gyrations,

(Ndes)

All 96%

% Gmm at the initial number of gyrations, Ni All 91.5% maximum

% voids filled with asphalt (VFA) at Ndes

9.5 mm Type I Min. 72; Max. 80

9.5Type II and 12.5 mm Min. 72; Max. 76

19 mm Min. 71; Max 76

25 mm Min. 69; Max 76

Fines to effective asphalt binder ratio (F/Pbe)

9.5 mm Type I 0.6 to 1.4

All other types 0.8 to 1.6

Minimum Film Thickness (microns)* All > 7.00

Minimum % Voids in Mineral Aggregate (VMA)

Note: VMA shall be calculated using the effective

specific gravity of the aggregate (Gse). See SOP-2SP.

25 mm 13.0

19 mm 14.0

12.5 mm 15.0

Type I 16.0

Type II 16.0

*Superpave Mixtures approved prior to January 31, 2012, may be adjusted to meet Minimum Film Thickness

requirements by the State Materials Engineer.

Surface layers for parking facilities:

Sieve Size Mixture Control

Tolerance

Design Gradation Limits, Percent Passing

4.75 mm Mix 9.5 mm Superpave

Type I

9.5 mm Superpave

Type II

1 in. (25.0 mm) sieve ± 8.0

3/4 in. (19.0 mm) sieve ±8.0** 100* 100*

1/2 in. (12.5 mm) sieve ±6.0 100* 98-100**** 98-100****

3/8 in. (9.5 mm) sieve ±5.6 90-100 90-100 90-100

No. 4 (4.75 mm) sieve ±5.6 75-95 65-85 55-75

No. 8 (2.36 mm) sieve ±4.6 60-65 48-55 42-47

No. 50 (300 μm) sieve +3.8 20-50

No. 200 (75 μm) sieve ±2.0 4-12 5.0-7.0 5.0-7.0

Range for Total AC + 0.4 6.00 - 7.50 5.50 - 7.25 5.25 - 7.00 153515351535

Subsurface layers for parking facilities:

All * and notes apply to both 828.2.03.B.1 and 828.2.03.B.2.

*Mixture control tolerance is not applicable to this sieve for this mix.

**Ensure mixture control tolerance is within ±10.0% for this sieve for 25 mm Superpave mixes.

*** Ensure mixture control tolerance is within ±8.0% for this sieve for 19 mm Superpave mixes.

****Ensure mixture control tolerance is within ±2.0% for this sieve for 12.5 mm and 9.5 mm Superpave mixes.

Note 1: Quality Acceptance Test Results for AC content deviating > ± 0.3 % from the approved Job Mix Formula

of the State Materials Engineer based on statistical trend.

Note 2: Range for % AC is Original Optimum AC (OOAC) at 65 gyrations prior to the Corrected Optimum AC (COAC)

calculation detailed in SOP 2 (Appendix D).

Volumetric limits for parking facilities are as follows:

Design Parameter Mix Type Limits

% of Max. Specific Gravity (Gmm) at design gyrations, Ndes) All 96%

% Gmm at the initial number of gyrations, Ni All 91.5 % maximum

% voids filled with asphalt (VFA) at Ndes 9.5 mm Type I Min. 72; Max. 80

Type II and 12.5

mm

Min. 72; Max. 78

19 and 25 mm Min. 71; Max 76

Fines to effective asphalt binder ration (F/Pbe) 9.5 mm Type I 0.6 to 1.4

All other types 0.8 to 1.6

Minimum Film Thickness (microns)* 4.75 mm > 6.00

All other types > 7.00

Minimum % Voids in Mineral Aggregate (VMA) 25 mm 13.0

Sieve Size

Mixture

Control

Tolerance

Design Gradation Limits, Percent Passing

12.5 mm Superpave 19 mm

Superpave

25 mm

Superpave

100*

1 in. (25.0 mm) sieve ± 8.0 100* 100* 90-100

3/4 in. (19.0 mm) sieve ±8.0** 98-100**** 90-100 55-89**

1/2 in. (12.5 mm) sieve ±6.0*** 90-100 60-89*** 50-70

3/8 in. (9.5 mm) sieve ±5.6 70-89 55-75

No. 8 (2.36 mm) sieve ±4.6 38-46 32-36 30-36

No. 200 (75 μm) sieve ±2.0 4.5-7.0 4.0-6.0 3.5-6.0

Range for Total AC + 0.4 5.00 - 6.25 4.25 - 5.50 4.00 - 5.25 153615361536

Design Parameter Mix Type Limits

Note: VMA shall be calculated using the effective specific gravity of

the aggregate (Gse). See SOP-2

19 mm 14.0

12.5 mm 15.0

9.5 mm Types I, II 16.0

* Mixtures approved prior to January 31, 2012, may be adjusted to meet Minimum Film Thickness requirements by

the State Materials Engineer.

See Section 400.

828.2.04 Fine-Graded Mixtures

Produce the mixture according to an approved mix design and Job Mix Formula. Ensure that fine-graded mixtures

meet the following mixture control tolerances and design limits:

ASPHALTIC CONCRETE - 4.75 mm Mix

Sieve Size Mixture Control Tolerance Design Gradation Limits, % passing

1/2 in. (12.5 mm) sieve* ±0.0 100*

3/8 in. (9.5 mm) sieve ±5.6 90-100

No. 4 (4.75 mm) sieve ±5.7 75-95

No. 8 (2.36 mm) sieve ±4.6 60-65

No. 50 (300 μm) sieve ±3.8 20-50

No. 200 (75 μm) sieve ±2.0 4-12

Range for % AC ±0.4 6.00 – 7.50

Design optimum air voids (%) 4.0 – 7.0

% Aggregate voids filled with AC 60 - 80

Minimum Film Thickness (microns) > 6.00

* Mixture control tolerance is not applicable to this sieve for this mix.

Note 1: Quality Acceptance Test Results for AC content deviating > ± 0.3 % from the approved Job Mix Formula

of the State Materials Engineer based on statistical trend.

Note 2: Range for % AC is Original Optimum AC (OOAC) at 50 gyrations prior to the Corrected Optimum AC (COAC)

calculation detailed in SOP 2 (Appendix D).

See Section 400.

See Subsection 106.3 and Section 400. Ensure individual test results meet the Mixture Control Tolerances listed in

Subsections 828.2, 828.2.01, 828.2.02, 828.2.03, 828.2.04, whichever applies.

See General Provisions 101 through 150.. 1537 1537 1537