Appendix C Tollway Asphalt Mixtures Special Provisions.pdf

ASPHALT MIXTURES (Illinois Tollway)

Effective: July 25, 2019 Revised: March 5, 2024

Table of Contents

1. Description.

2. Reference Standards.

3. Requirements.

4. Materials.

4.1. Fine Aggregate

4.2. Coarse Aggregate

4.3. Mineral Filler

4.4. RAP/FRAP/RAS Requirements

4.5. Asphalt Binder

4.6. Mix Additives

5. Mix Design.

5.1. Gradation Requirements

5.2. Volumetric Requirements

5.3 Recovered Asphalt Binder Performance Grade

5.4. Reclaimed Asphalt Pavement (RAP) and Fractionated RAP (FRAP)

5.5 Reclaimed Asphalt Shingles (RAS)

5.6 Asphalt Binder Replacement (ABR)

5.7 Performance Testing

5.8 Asphalt Binder Performance Grade

5.9 Mix Design Verification

1. Description. This work shall consist of designing Asphalt Mixes for the Illinois Tollway. Any verbiage relating to “Hot Mix Asphalt” Mixtures in the referenced documents is considered interchangeable with the Tollway’s use of “Warm Mix Asphalt” (WMA) Mixtures, unless specifically noted herein.

2. Reference Standards. The following documents are referenced in the Illinois Tollway Asphalt Mixtures Special Provision and must be followed in the asphalt mix design process unless revised herein.

2.1. Illinois Department of Transportation (IDOT) – Current Standard Specifications for Road and Bridge Construction

2.2. Illinois Department of Transportation (IDOT) – Supplemental Specifications and Recurring Special Provisions

2.3. Illinois Department of Transportation (IDOT) – Manual of Test Procedures for Materials

2.4. Illinois Department of Transportation (IDOT) – Manual of Aggregate Quality Test

Procedures

2.5. Illinois Tollway – Illinois Tollway Manual of Test Procedures (referred to as TTP)

2.6. Illinois Tollway – Approved List of Asphalt Binder and Mixture Modifiers

2.7. Illinois Tollway – Approved List of Warm Mix Asphalt (WMA) Technologies

2.8. Illinois Tollway – Special Provision for Reclaimed Asphalt Materials (RAM)

3. Requirements. Contractor and Consultant laboratories performing the tasks set forth in this special provision shall either be AASHTO resource Accredited or meet the minimum

APPENDIX C

requirements specified in the current version of the IDOT policy memorandum 6-08 “Minimum Private Laboratory Requirements for Construction Materials Testing or Mix Design,”, as determined by Tollway Materials.

4. Materials.

4.1. Fine Aggregate – If the contractor proposes a non-IDOT-approved source, testing and acceptance procedures must be reviewed and approved by Tollway Materials. Fine Aggregate shall conform to Article 1003.03 of the Standard Specifications except as modified herein.

Revise the first paragraph of Article 1003.03(a) of the Standard Specifications to read:

“(a) Description. Fine aggregate for Asphalt Mixtures may consist of sand, stone sand, slag sand or steel slag sand as permitted by Tollway Table 1. For gradation FA 22, uncrushed material will not be permitted. Fine aggregate for SMA shall consist of stone sand, slag sand, or steel slag sand.”

Revise the first through third paragraphs of Article 1003.03(c) of the Standard Specifications with the following.

“(c) Gradation. Fine aggregate gradations for Asphalt Mixtures shall be FA 1, FA 2, FA 20, FA 21, or FA 22, as permitted by Tollway Table 1.

Tollway Table 1 – Allowable Fine Aggregate Gradations

Mixture Type FA1 FA2 FA20 FA21 FA22

SMA Not Permitted

Permitted Not

Permitted1/ Permitted Binder and Surface

Course Permitted

IL-4.75 Permitted

Asphalt Stabilized Subbase

Permitted

1/ Allowed if no RAP, FRAP or RAS in mix

For mixtures with a Ndesign = 90 and for mixture IL-4.75, at least 50 percent of the required fine aggregate fraction shall consist of either stone sand, slag sand, or steel slag meeting the FA 20 gradation.

For mixture IL-19-0, Ndesign = 90, the fine fraction shall consist of at least 67% manufactured sand meeting the FA 20 gradation. The manufactured sand shall be stone sand, slag sand, steel slag sand, or combinations thereof.”

4.2. Coarse Aggregate – If the contractor proposes a non-IDOT-approved source, testing and acceptance procedures must be reviewed and approved by Tollway Materials. Coarse Aggregate shall conform to Article 1004.03 of the Standard Specifications, except as modified herein.

Revise Article 1004.01 (b) of the Standard Specifications to include the Additional Requirements for SMA Coarse Aggregate as listed in Tollway Table 2.

“Tollway Table 2 – Additional Requirements for SMA Coarse Aggregate

Quality Test Test Method &

Procedure

Coarse Aggregate Material

Crushed Gravel Dolomite Category I FRAP for

SMA

Coarse Aggregate

Angularity

ITP 5821

>98% two fractured faces

Flat & Elongated ITP 4791 ≤ 10% (5:1) ≤ 10% (5:1) LA Abrasion ITP 96 ≤ 28.0% ≤ 28.0%

Micro-Deval1/ ASTM D6928 or

AASHTO T327

≤ 11.0% ≤ 11.0% <9.0%

1/ All Micro-Deval testing must be performed by a laboratory with AASHTO Re: Source aggregate accreditation. The Engineer reserves the right to verify Micro-Deval testing.”

Revise Article 1004.03(a) to add Tollway Table 3 for Allowable Coarse Aggregate for SMA Mixes.

“Tollway Table 3 – Allowable Coarse Aggregate for SMA Mixes

Coarse Aggregate Friction Surface Surface Unmodified

SMA1/

Binder

Crushed Steel Slag

Permitted Permitted Permitted

Not Permitted Quartzite

Permitted Granite

Diabase / Trap Rock Crushed Gravel

Not Permitted Dolomite Not Permitted ≤ 25% ≤ 25%

1/Crushed Steel Slag is not permitted in Unmodified SMA if used in the Binder

4.3. Mineral Filler – Shall conform to Article 1011 except as modified herein.

Add the following to Article 1011.01 of the Standard Specifications.

“As an option, collected baghouse dust may be used in lieu of manufactured mineral filler, provided: 1) there is enough available for the production of the mix for the entire project, and 2) a mix design was prepared with collected baghouse dust.”

4.4. RAP/FRAP/RAS Requirements – RAP/FRAP/RAS stockpile production shall conform to the Illinois Tollway Reclaimed Asphalt Materials (RAM) special provision. Additionally:

(1) The coarse aggregate in all RAP and FRAP shall be equal to or less than the nominal maximum size requirement for the asphalt mixture to be produced. Only FRAP that is processed over a 5/16 in. or smaller screen will be permitted in the IL-4.75 mm mix.

(2) RAP and FRAP stockpiles containing steel slag shall be approved for use in surface mixtures only.

4.5. Asphalt Binder –

All asphalt binder shall conform to the Article 1032.05 of the Standard Specifications except as modified herein.

Revise Table 1 of Article 1032.05 (b) as follows.

Add “SB/SBS PG 64-34” in Row 2, Column 2, underneath “SB/SBS PG 70-28.”

Revise Table 2 of Article 1032.05 (b) as follows.

Add “SBR PG 64-34” in Row 2, Column 2, underneath “SBR PG 70-28.”

Revise Table 1 and 2 Notes of Article 1032.05 (b) with the following.

“Note: The SBS/SBR PG 76-22, SBS/SBR PG 70-22, SBS/SBR PG 70-28 or SBS/SBR PG 64-34 binder shall meet the requirements of Article 1032.05(b) of the Standard Specifications. In addition, the elastic recovery of the asphalt binder used shall be a minimum of 80.”

Add the following paragraph to Article 1032.05 (b).

“The base asphalt binder that is blended with the Terminal Blend Ground Tire Rubber (GTR) or Dry Process GTR shall meet the requirements of Article 1032.05 of the Standard Specifications. The GTR blended asphalt shall comply with the specified PG Grade in accordance Table 1 of Article 1032.05 (b) of the Standard Specifications with exception to the Separation of Polymer test and Force Ratio. In addition, the elastic recovery shall be a minimum of 75% for all grades of GTR blended asphalt binder. Dynamic Shear Rheometer tests on GTR blended asphalt binder shall use a 2.00mm gap for 25mm plates.”

4.6. Mix Additives

Fibers – Replace Article 1030.02(h) (Note 2) of the Standard Specifications with the following.

“Note 2. A fiber additive shall be included in all SMA mixtures. For Cellulose or Mineral Fiber, the fiber additive shall comply with the requirements of AASHTO M 325. RAS may be used as a fiber additive in Stone Matrix Asphalt (SMA) mixtures. Fibers may be used in other asphalt mixtures if approved by Tollway Materials.”

Warm Mix Additives – Replace Article 1030.02(i) (Note 3) of the Standard Specifications with the following.

“Note 3. Warm mix additives/processes shall be on the Illinois Tollway’s Approved List of Warm-Mix Asphalt (WMA) Technologies.”

Asphalt Modifiers – GTR and Rejuvenators shall be on the Illinois Tollway’s Approved List of Asphalt Binder and Mixture Modifiers.

5. Mix Design.

5.1. Gradation Requirements – Shall conform to Article 1030.05 of the Standard Specifications except as modified herein.

Revise the Table in Section 1030.05(a)(1) of the Standard Specifications as follows.

“Tollway Table 4 - Gradation Requirements

Mixture Composition Range (% Passing) 1/

Sieve Size

SMA IL-

12.5 4/

SMA IL-

9.5 4/

IL-19.0 IL-12.5 IL-9.5 IL-4.75

Asphalt

Stabilized Subbase

1 in. (25 mm) - - 100 - - - 100

3/4 in. (19.0 mm) 100 - 90 – 100 100 - - 90 - 100

1/2 in. (12.5 mm) 82 – 100 100 69 – 89 90 – 100 100 - 69 - 89

3/8 in. (9.5 mm) 65 max 90 – 100 - 89 max 90 – 100 100 -

No. 4 (4.75 mm) 20 – 30 36 – 50 45 – 60 28 – 65 32 – 69 90 - 100 45 – 60

No. 8 (2.36 mm) 16 – 243/ 16 – 32 30 – 45 28 – 48 345 – 522/ 70 - 90 30 – 45

No. 16 (1.18 mm) - - 20 – 35 10 – 32 10 – 32 50 - 65 20 – 35

No. 30 (600 m) 12 – 16 12 – 18 - - - 35 - 55 -

No. 50 (300 m) 10 – 15 - 8 – 16 4 – 15 4 – 15 15 - 30 8 – 16

No. 100 (150 µm) - - 6 – 9 3 – 10 3 – 10 10 - 18 6 – 9

No. 200 (75m) 8 – 10 7.5 – 9.5 3 – 6 4 – 6 4 – 6 7 - 9 3 – 6

1/ Based on percent of total aggregate weight.

2/ The mixture composition shall not exceed 44 percent passing the #8 (2.36 mm) sieve for surface courses with Ndesign = 90.

3/ When establishing the Adjusted Job Mix Formula (AJMF) the percent passing the #8 (2.36 mm) sieve shall not be adjusted above 24 percent.

4/ When the bulk specific gravity (Gsb) of the component aggregates vary by more than 0.20, the blend gradations shall be based on percent by volume.

5/ When establishing the Adjusted Job Mix Formula (AJMF) the percent passing the #8 (2.36 mm) sieve shall not be adjusted below 34 percent.”

All asphalt plants are required to use positive dust control. The contractor may choose to develop the mix design with less than 1.0 percent mineral filler added in the laboratory.

5.2. Volumetric Requirements - Shall conform to Article 1030.05 of the Standard Specifications except as modified herein.

Revise the table of Article 1030.05(b) of the Standard Specifications to the following tables.

“Tollway Table 5 – Binder and Surface Course Mix Volumetric Requirements

VOLUMETRIC REQUIREMENTS

Binder and Surface Course Mixes

Ndesign Design

Air Voids Target %

Voids in the Mineral Aggregate (VMA), % minimum

Ratio Dust/Asphalt

Binder IL-19.0 IL-12.5 IL-9.5

30 3.0 N/A N/A 15.0

1.0 Max

50 3.0 13.52/ 14.0 15.0

70 4.01/

13.5 14.0 15.0 75 3.5

90 4.0

1/ Target air voids on IL-19.0 N70 Binder shall be 3.5%

2/ IL-19.0 N50 Binder 3.0% void mixes placed on shoulders or temporary pavement are allowed a VMA minimum of 12.5%”

“Tollway Table 6 – SMA, IL-4.75mm, and Asphalt Stabilized Subbase Volumetric Requirements

Property

Mixture Type

SMA IL-4.75

Asphalt Stabilized

Subbase

Design Air Voids

3.5 % @ 80 Gyrations

3.5 % @ 50 Gyrations

2.0 % @ 50 Gyrations

Voids in the Mineral Aggregate (VMA), % (Minimum)

16.0 % (for specific gravity of coarse aggregate

< 2.78) 1/

17.0 % (for specific gravity of coarse aggregate

≥ 2.78) 1/

18.5 11.0

Ratio Dust/Asphalt Binder

- 1.0 max 1.2 max

Draindown (%) (Maximum)

0.22/ -

1/The calculation for the Gsb is a weighted average including the RAP and/or FRAP

2/The draindown shall be determined at the job mix formula asphalt binder content at the mixing temperature of 350⁰F, as per AASHTO T305.”

5.3. Recovered Asphalt Binder Performance Grade

Reserved.

5.4. Reclaimed Asphalt Pavement (RAP) and Fractionated Reclaimed Asphalt Pavement

(FRAP)

All stockpiles shall conform to the Illinois Tollway Reclaimed Asphalt Materials (RAM) special provision.

Tollway Table 7 – Allowable RAP in Asphalt Mixtures

RAP Type

Mixture Type

SMA and IL-4.75mm

Surface Course

Binder Course

Asphalt Stabilized Subbase

Homogenous

Not Permitted

Permitted Permitted

Permitted Conglomerate 3/8

Conglomerate 5/8 Not Permitted

Conglomerate DQ Not Permitted

Tollway Table 8 – Allowable FRAP in Asphalt Mixtures

FRAP Type

Mixture Type

SMA IL – 4.75mm Unmodified SMA, Binder, Surface, and Asphalt Stabilized Subbase

Category I Fine Permitted1/ Permitted

Permitted Coarse ≤15%2/ Not Permitted

Category II Fine Not

Permitted3/

Permitted

Coarse Not Permitted

1/ When using FRAP for SMA, the fine portion Category 1 FRAP may be used separately or as proportioned with the stone sand.

2/ Category 1 Coarse FRAP may be increased to 25% provided it is from a friction SMA source.

3/ A Category 2 Fine-FRAP source may be used in the mix design for SMA provided that the fine aggregate angularity of the fine FRAP sand, following the Illinois Tollway Modified Test Procedure (TTP) 002, equals 45.0 or greater.

5.5. Reclaimed Asphalt Shingles (RAS) in Asphalt Mixtures

Quality requirements of RAS materials can be found in the Illinois Tollway Special Provision for Reclaimed Asphalt Materials (RAM).

RAS shall not exceed 5.0 percent by weight of the total mix for all asphalt mixtures.

For asphalt mixtures that contain RAS that has not been mechanically blended with any other product, a bulk specific gravity (Gsb) of 2.300 shall be used for RAS in the design.

Blended RAS products may have other specific gravity values for use in asphalt mix design but shall be verified by the Illinois Tollway. When the blended RAS product is approved by the Illinois Tollway an approval letter will be sent to the supplier with the approved gradation and specific gravity assignment.

5.6. Asphalt Binder Replacement (ABR)

Virgin asphalt binder performance grade (PG) shall depend on the mix type, the types of reclaimed materials, the level of binder replacement, and the presence of a rejuvenator.

For SMA and IL-4.75, the contractor shall use a SBS polymer, a Terminal Blend GTR, or a Dry Process GTR to modify the asphalt mixture.

Tollway Table 9 - RAM, ABR, and Asphalt Binder Requirements

Reclaimed Asphalt Material (as permitted in Tollway

Tables 7 & 8)

RAP1//FRAP/RAS FRAP/RAS

Category 12/ FRAP with RAS

ABR 0-17% 18-33% 34-50%

A llo w a bl e

M ix

O p tio n s

SMA and

IL-4.753/

SBS/SBR 70-28

GTR PG 70-28

PG 58-28 10%4 Dry GTR

SBS/SBR 64-34

GTR PG 64-34

PG 52-346/ 10%4 Dry GTR

Unmodified SMA and

Binder & Surface Course

PG 58-287/9/ PG 52-345/6/7/10/

Asphalt Stabilized Subbase

PG 58-287/8/

1/ RAP not allowed in SMA 2/ Category II is allowed in Binder and Surface Course, and Asphalt Stabilized Subbase 3/ IL-4.75 ABR cannot exceed 33% 4/ Dry GTR shall be added at the WMA Plant at a rate of not less than 10% nor greater than 12%, by weight, of the virgin asphalt cement needed for the mix design.

5/ Up to 60% ABR on N50 IL 19.0mm Binder 6/ PG 46-34 shall be considered an equivalent to PG 52-34 7/ Alternate Grades or Modifiers may be considered with approval of the Engineer 8/ Up to 65% ABR on Asphalt Stabilized Subbase 9/ PG 64-22 + Rejuvenator is an allowed substitute for PG 58-28 for shoulders or temporary pavement 10/ PG 58-28 or 52-28 + Rejuvenator is an allowed substitute for PG 52-34 or PG 46-34 for shoulders or temporary pavement

Rejuvenators may only be used in Unmodified SMA and Binder & Surface Course mixtures placed on the shoulder or temporary pavement. The Contractor shall demonstrate the dosage of rejuvenator required to meet the PG specified in Table 9 above using a Continuous Performance Grading of the combined asphalt binder and rejuvenator per AASHTO M 320 and D7643. This dosage must be used in the design and follow all requirements per the Asphalt Mixtures Design Verification Procedure (TTP 005).

For all asphalt mixtures containing RAS or more than 17 percent Asphalt Binder Replacement, a chemical additive shall be used as the WMA technology.

5.7. Performance Testing

Replace 1030.05(c) and 1030.05(d) with the following.

“(c) The following tests are additionally required for mix design.

The contractor shall determine the asphalt mix maximum rut depth using the Hamburg Wheel Tracking (HWT) test. Testing shall conform to Illinois Tollway Modified Test Procedure AASHTO T324. The maximum rut depth shall meet Hamburg Requirements in Table 10.

Determination for Need of Anti-Strip Additive. The mixture designer shall determine if an additive is needed in the mix to prevent stripping. The determination will be based on the stripping inflection point as calculated according to the Illinois Tollway Modified Test Procedure AASHTO T324. The stripping inflection point requirements are listed in Table 10.

For WMA designs proposed using organic or chemical additives, Hamburg Wheel testing according to Illinois Tollway Modified AASHTO T324 shall be conducted on a laboratory mixed sample at the recommended WMA additive dosage rate.

Tollway Table 10 - Hamburg and Stripping Inflection Point Requirements

Mixture Type Maximum Rut

Depth

Maximum Rut Depth Recorded at # Wheel

Passes

Minimum # of Wheel Passes at

Stripping Inflection Point1

SMA2/ 6 mm 20,000 15,000

Unmodified SMA

9 mm 15,000 10,000

IL-4.75 12.5 mm 15,000 10,000

Mainline Binder Course Ndesign > N50

12.5 mm 15,000 10,000

Mainline Binder Course Ndesign = N50

12.5 mm 10,000 7,500

Surface Course Ndesign ≤ N70

12.5 mm 10,000 7,500

Shoulder Binder Course 12.5 mm 7,500 5,000

Asphalt Stabilized Subbase

12.5 mm 7,500 5,000

1/ If the Stripping Inflection point does not meet minimum requirements, the designer has the option to perform the Tensile Stripping Ratio (TSR) test per article 1030.04(c) 2/ Calculation of the stripping inflection point is not required for SMA with less than 4.0 mm rut depth at 20,000 passes.

The contractor shall determine the asphalt mix fracture energy using the Disk-Shaped Compact Tension (DCT) Test. Testing shall conform to Illinois Tollway Modified ASTM D7313. For WMA designs proposed using organic or chemical additives, DCT testing according to Illinois Tollway Modified ASTM D7313 shall be conducted on a laboratory mixed sample at the recommended WMA additive dosage rate. Fracture energy shall meet the DCT requirements of Table 11.

Tollway Table 11 – DCT Requirements

Mixture Type Minimum Fracture Energy

SMA – Friction Surface 775 J/m2 SMA – Surface 700 J/m2 SMA – Binder

650 J/m2

Unmodified SMA 500 J/m2

IL 4.75 450 J/m2 Mainline Binder Course

Ndesign > N50 425 J/m2

Mainline Binder Course Ndesign = N50

450 J/m2

Surface Course Ndesign ≤ N70

450 J/m2

Shoulder Binder Course 425 J/m2 Asphalt Stabilized Base N/A

5.8. Asphalt Binder Performance Grade

Reserved.

5.9. Mix Design Verification

IDOT verified mix designs will be accepted as long as they meet the requirements of this special provision. If the contractor requests to use an IDOT verified mix design and intends to add a warm mix chemical additive for use on the Tollway, the contractor must provide test results of a 1-point at optimum AC using the additive, showing compliant volumetrics, SIP, Hamburg and DCT.

For all non-IDOT approved mix designs, the mix design verification process shall be according to the Tollway Standard Method of Test for Asphalt Mixture Design Verification Procedure TTP 005.

Mixture components may not be substituted within an approved mix design. A new mix design verification process is required for alternate mixture components. Substitutions for neat unmodified asphalt binder of the same AASHTO M 320 grade will be allowed if the Contractor provides test results of a 1-point verification at optimum AC using the substituted asphalt binder showing compliant volumetrics, SIP, Hamburg and DCT.

Asphalt binder substitutions will not be allowed for mixes that use an SBS polymer, a Terminal Blend GTR, or a Dry Process GTR, or a Rejuvenator; changes to these asphalt binders require a new mix design.