Tn 75 Registration Warm Mix Asphalt Design

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State of Queensland (Department of Transport and Main Roads) 2013

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Technical Note 75

Registration of Mix Designs for AsphaltManufactured using Warm Mix Asphalt Technologies

November 2012


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Department of Transport and Main Roads November 2012

Registration of Mix Designs for Asphalt Manufactured Using Warm Mix Technical Note 75

Page 1 of 6

1 INTRODUCTION

1.1 General

The technical note provides guidance to TMR project managers, contract administrators and

registered asphalt suppliers on the conditions of use and procedures for registration of mix designs forasphalt manufactured using warm mix asphalt technologies.

1.2 Benefits of Warm Mix Asphalt

Warm mix asphalt (WMA) is asphalt manufactured and/or compacted at a lower temperature than

conventional hot mix asphalt (HMA).

WMA may have one or more of the following benefits:

Improved sustainability through reduced energy consumption during asphalt manufacture

Reduced climate impact through a reduction in greenhouse gas generation

Improved safety benefits in construction since the materials and asphalt are at lower temperature

compared to HMA

Improved productivity as works that include asphalt can be opened to traffic sooner because WMA

layers can be covered with subsequent layers earlier (than HMA), and/or

Enables the use of longer haul distances for asphalt pavement construction.

A range of technologies are available to produce WMA, most of which have been developed relatively

recently. Vuong et al (2011) has identified sixteen different WMA technologies1which can be broadly

grouped into six categories. These technologies / categories are summarised in Table 1.

1.3 AAPA/Austroads WMA Validation Project

Austroads, in conjunction with AAPA and its members, is currently finalising a major project to assess

the performance of dense graded asphalt (DGA) asphalt surfacings manufactured using three WMA

technologies. Test sections for the AAPA/Austroads WMA Validation Project were constructed in April

2010 on Sydney Road (also called the Old Hume Highway) near Melbourne after many months of

planning. The project provided a short term (2 years) performance comparison between WMA

(containing specific WMA technologies) and HMA on a six lane urban arterial road2in Melbourne. The

project included extensive laboratory and field testing as part of this validation process.

A draft (unpublished) Austroads report has been produced for this project, and a final report is

programmed for completion in the near future.

Table 1 Commercially Available WMA Technologies as of June 20113(adapted from Vuong et

al 2011)

Category Product / Process Supplier

Low energy asphalt (LEA1) LEA-COSequential aggregate coating

and binder foamingLow emission asphalt (LEA2) Suit-Kote Corporation

1Vuong (2011) noted that new technologies are continuing to come onto the market. The list of products is likelyto expand with time.

2AADT for the trial site was 24,000 vehicles per day with 14% commercial vehicles. Intersections (and

approaches) were excluded from the trial.3WMA technologies highlighted by shading were assessed in a DGA surfacing as part of the AAPA/Austroads

WMA Validation Project


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Category Product / Process Supplier

WAM-Foam Shell International / Kolo-

Veidekke

AQUABlack Maxam Equipment Inc

Double Barrel Green Astec Industries

Terex WMA Terex Corporation

Ultrafoam GX Glencor Industries

Water-based binder foaming4

Ammann Foam Ammann

Advera WMA PQ CorporationBinder foaming with water-

bearing additiveAspha-Min Eurovia Services

CECABASE RT Arkema Group

Evotherm MeadWestvaco Asphalt

Innovations

Chemical additive surfactants

Rediset WMX Akzo Nobel NV

Asphaltan B Romonta GmbHOrganic additives

Sasobit Sasol Wax

Shell Thiopave ShellCombined binder modifier /

organic additivesTLA-X Trinidad and Tobago Ltd

2 IMPLEMENTATION OF WMA TECHNOLOGIES BY TMR

2.1 General

The quantity of WMA being used on road construction projects throughout the world has increased

significantly in recent years. Although most jurisdictions have not established the long term

performance characteristics of these mixes, the rapid increase in usage has been primarily driven by

the benefits outlined in Section 1 of this technical note.

TMR will be adopting a staged approach to the implementation5of WMA. This approach is similar to

that being adopted by many jurisdictions throughout the world.

2.2 Condit ions of Usage on TMR Projects

Until sufficient local performance information is available6for mixes containing a particular WMA

technology, WMA mix designs should be used in low risk applications, as defined in Table 2. However,

registered mixes may also be used in high risk and very high risk applications, if approved by the

4Any water-based binder foaming system (which has been developed by a reputable asphalt plant manufacturer)that is installed and functioning as per the manufacturers specifications/recommendations, will be considered byTMR as equivalent to the Double-Barrel Green system used in the AAPA/Austroads WMA Validation Project.

5A staged approach to implementation means that usage of WMA will generally be limited to roads carrying lowto medium traffic volumes. Once sufficient local performance information is available, usage will be extended toroads carrying higher traffic volumes.

6Local performance information is required to confirm the performance of WMA, complying with TMR technicalstandards (and subject to Queenslands environmental conditions and traffic loadings), is at least equivalent toHMA.


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Page 3 of 6

Principal. As performance information for TMR registered WMA mix designs becomes available, the

limits and performance risk categories (defined herein) may be varied at the discretion of the

Director (Pavements & Materials). The actual unrestricted usage limits applicable to a particular mix

design shall be stated on the mix design certificate.

Table 2 Performance Risk Category & Conditions for Project Level Approved of RegisteredWMA Mix Designs

WMA Technology assessed as part of the AAPA/Austroads WMA

Validation Trial (refer technologies highlighted in Table 1) or other

documented trials7

Yes No

Yes

Low Performance Risk

(i.e. unrestricted usage)

Approval for use may begranted by the Administrator.

i.e. referral to the Principal

not required.

High Performance Risk

Project level risk assessment required.

Approval for use shall be referred to thePrincipal.8Application

complies with

the

requirements

of Table 3No High Performance Risk

Project level risk assessment

required. Approval for use

shall be referred to the

Principal8.

Very High Performance Risk

Project level risk assessment required.

Approval for use shall be referred to the

Principal.8

2.3 Early Traffick ing of WMA

For all mixes containing temperature reducing additives (except those that have a stiffening effect on

the mix such as Sasobit) the maximum temperature at the time of opening to trafficking (refer Clause

12.2.13 of MRTS30) shall be reduced from 65C to 60C.

7Documented trials are trials undertaken on a heavily trafficked public road by any Australian state road authorityor local government, and the results of these trials:

are published in a publicly available technical report; and

demonstrate favourable performance.

The report should include, as a minimum, mix characterisation test results for the production mix and results ofin-field functional performance properties (such as visual condition, surface texture, rutting and roughness)recorded after construction and over at least a two year period. The report should be submitted to the PrincipalAdvisor (Materials Testing) as part of the asphalt suppliers submission for mix design registration.

8Where approval by the Principal is required, the proposed usage of WMA should be raised by the Contractorduring the tendering phase of the project. This ensures the Principal has sufficient lead time to assess theContractors proposal. Additional requirements, such as a longer than normal defects liability period (e.g. 2years), may be nominated by the Principal following a risk assessment being undertaken.


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Table 3 Interim Limits for Unrestricted usage of WMA9

Pavement

Layer

Nominal Mix

Type / SizeStandard

10 Binder

Traffic Category

(refer Table 4)

C320 1

DG10M1000/320 or A5S 3

C320 2DG14

MRTS30

M1000/320 or A5S

DG14HP3

DG14HSMRTS31 A5S

5

SMA MRSS548 A5S, A10S 8

Surface

OGA MRTS30 A5S 5

DG10, DG14,

DG20MRTS30 C320, M1000/320, A5S 3

DG14HP 4

Corrector

or

Binder

DG14HSMRTS31 A5S

5

DG14, DG20,

DG28MRTS30 C320 or C600 3

Base DG14HS

DG14HP

DG20HM

MRTS31 A5S or C600 5

Table 4 WMA Mix Design Traffic for Unrestricted usage (to be stated on the mix designcertificate)

Traffic CategoryMaximum Design Traffic (ESA per day in the design lane in the year of

opening)

Free flowing traffic conditions High shear situations11

1 300 300

2 1000 300

3 1000 1000

4 3000 1000

5 3000 3000

9The applicable traffic category for a particular WMA technology and mix type may be varied by the Director(Pavements & Materials) as performance information for WMA mixes and technologies becomes available.

10For MRTS30 mixes that also comply with the requirements of MRTS31, the applicable MRTS31 traffic category(refer Table 3 of this technical note) shall apply to the mix design.

11An example of a high shear situation is a signalised intersection (including approaches).


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Traffic CategoryMaximum Design Traffic (ESA per day in the design lane in the year of

opening)

6 No limit 3000

7 No limit No limit

8 Not applicable. Mix type is only used on a project specific trial basis.

3 MIX DESIGN REGISTRATION PROCEDURES

3.1 General

Mix designs containing additives shall be verified in accordance with the requirements of the relevant

TMR technical standard/s applicable to the asphalt type.

The mix conditioning procedures and compaction temperature for warm mix asphalt test specimens

are subject to considerable ongoing research and are being addressed at a national level12

. In the

interim, the supplier shall submit test results

13

and technical data that demonstrate the appropriatecompaction temperature for Marshall Test specimens as part of their mix design submission. The

following compaction temperatures shall be used for preparation of specimens for the following tests

(as appropriate to the relevant technical standard):

Mix Design Registration:

a) For moisture sensitivity, wheel tracking, and resilient modulus testing, the standard

temperatures for HMA shall apply,

b) For voids at 250 cycles testing, the compaction temperature nominated by the Contractor for

Marshall Test specimens shall apply, and

c) For binder drainage testing, the test temperature shall be not less than the maximum asphaltmanufacturing temperature nominated by the Contractor.

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Complete characterisation tests:

a) For all relevant complete characterisation tests, specimens shall be compacted at the

compaction temperature nominated by the Contractor for Marshall Test specimens.

For heavy duty asphalt mixes, wheel tracker testing shall also be completed with the mix design binder

and the mix shall comply with the requirements nominated in the footnote to Table 10.3.3.1 of

MRTS31.

Once the performance characteristics of asphalt mixes containing a particular WMA technology have

been established, the extent of testing required for mix design registration may be reduced at thediscretion of the Principal Advisor (Materials Testing).

12AAPA national technical committee is developing an advisory note for laboratory compaction of WMAspecimens. Once the advisory note is released, TMR will consider adopting the AAPA recommendations in itstechnical standards.

13The test results shall demonstrate the compaction temperature required to achieve the same air voids in themix with the WMA technology as the mix compacted at the standard compaction temperature without the WMA

technology.14The maximum manufacturing temperature nominated by the Contractor shall not exceed the limits stated in therelevant technical standard.


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3.2 WMA Addi tives that Stiffen the Mix

For WMA technologies that significantly stiffen the mix at in-service temperatures (such as SASOBIT

when added at high concentrations (> 1.5%)), a more detailed assessment of the mix properties and

their effect on the pavement design is recommended. Additional testing for properties such as resilient

modulus and fatigue will be required.

3.3 WMA Technologies that Cannot be Assessed by Laboratory Mix Testing

For WMA technologies, such as water-based binder foaming systems, where it is not practical to

produce laboratory mix, the mix design shall be assessed as a hot mix asphalt design in the

laboratory. However, wheel tracking and sensitivity to water of the mix shall be tested as part of the

production trial for MRTS31 and MRSS548 mix designs. Samples of production mix shall be

compacted in the laboratory as soon as possible but not more than 6 hours after the mix is

manufactured in the asphalt plant.

3.4 Moisture Content of WMA

Due to the lower production temperatures typically used for WMA and because water is used as part

of some WMA technologies, there is a greater potential for non-conformance with the production mix

moisture content requirement nominated in the technical standards (refer Clause 12.2.2.1 of

MRTS30). Moisture content testing shall be completed during the production trial (and at any other

time nominated by the Administrator).

3.5 Issuing of Asphalt Mix Design Registration Certificates

Mix designs that use WMA technologies shall be conditionally registered to the relevant TMR technical

standard in accordance with this technical note. The appropriate traffic category applicable to

unrestricted usage (low risk applications) shall be stated on the mix design certificate.

4 PROJECT EVALUATION AND POLICY REVIEW

Limited local performance information is currently available for WMA complying with TMR technical

standards. To assist with future updates of this technical note, Asphalt Suppliers, Project

Administrators and TMR Regions are encouraged to provide the following information to the Principal

Engineer (Road Surfacings):

Project location (road, chainage, etc)

Mix design information, including full details of the WMA technology used

Details of the layers within the pavement structure where WMA was used

Test results (production and construction compliance)

Regular measurements of performance (such as road surface shape (roughness and rutting),surface texture depth, visual condition and skid resistance), and

Core logs (for cores extracted from the pavement not less than one year after construction) to

confirm structural integrity.

This technical note will be updated once sufficient local data has been accumulated to confirm the in-

service performance of WMA.

5 REFERENCES

Vuong B, Sharp K & Boer S, Review of Validation Trials of Warm Mix Asphalt Pavements, Draft

Report, Austroads Project TT1454, Austroads, Sydney, Australia, 2011 (Unpublished).

Documents

Tn 75 Registration Warm Mix Asphalt Design