Presented at: Rutgers Asphalt Paving Conference

March 8, 2011Presented by: Eileen Sheehy, P.E.

Manager, Bureau of Materials NJDOT

Topics for DiscussionWarm Mix AsphaltIndependent Assurance CoringRide Quality SpecificationAsphalt Binders for Performance Based

MixesCurrent HMA Research

Performance Based SpecificationsRAP in HMANortheastern States’ RAP Pooled Fund Study

Warm Mix AsphaltNJDOT has done some warm mix asphalt trials over

the past 3 years. Most extensively used to aid in compaction for late season paving or in specialty mixes to reduce the laydown temperature.

All trials used additives – either surfactants or waxes.

FHWA support of WMA as part of Every Day Counts initiatives. http://www.fhwa.dot.gov/everydaycounts/

NJDOT/NJAPA/FHWA Task Force established November 2010 to implement WMA on NJDOT projects.

Warm Mix Asphalt Task GroupTask Group is working on a specification to be

put out for bid on 3-6 projects this coming year.Proposed specification allows a trial of any

WMA technology. Extra samples are need of both the WMA and the HMA on the project to further the research being done.

In addition, NJDOT will entertain proposals from contractors to try WMA on projects that call for HMA mixes.Foaming systems will be considered.

NEAUPG WMA Task GroupThe Northeastern Asphalt User/Producer

Group has formed a task group to consider a more uniform approach to WMA in the Northeast.

Preliminary discussions are to have a region-wide approved products list (or qualified products list).

Consideration is being given to following the NYDOT protocols for approving technologies.

Task Group has been working on a definition of WMA.

Independent Assurance Program for CoringNJDOT will continue the Independent

Assurance Program for Coring in 2011.FHWA requires IA on Federally funded

projects.NJDOT usually uses the same IA Programs on

State funded projects.NJDOT has a Consultant on board to take

Independent Cores for testing in the NJDOT Laboratory and perform analysis of the results.

Ride Quality SpecificationPresentation from last year gave the

background of the new IRI specification for pavements.

Set targets based on number of lifts of paving, IRI of existing road, etc.

Based on the amount of “impediments” (obstacles to good paving), lots will be excluded from pay adjustment.

Expect to see the new specification in all future projects, so please review the special provisions for projects to know what the ride quality specification is for a project.

New IRI Specification ExampleExcluded Lots

Pay Equations for Pavement Ride Quality for 0.01 Mile

Route 00 NBMP 5.0 to MP 10.0

----------------------Route 00 SBMP 10.0 to MP 5.0

1 in Lane 13 in Lane 2

-------------2 in Lane 115 in Lane 2

IRI < 28 PA = $50

28 < IRI < 48

PA = $120.00 – ($2.5 x IRI)

48 < IRI < 58

PA = $0

58 < IRI < 128

PA = (IRI – 58) x (– $7.1429)

IRI > 128 Remove & Replace

Setting the Target IRIThe proposed model is of the following form:

IRISPECIFIED = (IRIBASELINE) • (A1) • (A2) • (A3) • … • (Ak)

Where,

IRIBASELINE = standard level of IRI desirable for pay-adjustment = $0.0

IRISPECIFIED = adjusted level of IRI to be specified based on project-specific conditions

Ai = factors (variables) that are project specific

k = Number of different factors in the equation

Generalized Factors

Factor Symbol

Speed Limit (MPH) AS

No. of Operations AO

Existing Roughness (IRI) AE

Composite Pavement AC

Speed Limit Factors

Factor for Number of Operations Number of operations is defined as

the number of improvement events. For example, milling 2" followed by

an overlay of 2" is considered to be 2 operations.

Or, milling 2" followed by paving 2" of intermediate and 2" of surface is considered to be 3 operations.

Factor for Existing Roughness This factor recognizes the difficulties in

achieving a smooth pavement when the existing pavement is rough.

The “number of operations” (AO) and the “existing roughness” (AE) are inter-connected factors and consideration of both factors contribute to determining the target IRI.

Combined Number of Operations and Existing Roughness Factor

Composite Pavement Factor If the overlay on bare PCC

pavement is > 8", exclude using a composite pavement factor.

If an existing overlay is to be resurfaced with or without milling, the composite pavement factor should not be applied if the total HMA thickness is > 8“ after the overlay.

Localized Factors Used to Determine Excluded Lots

Example of Excluded Lots Calculations

New IRI Specification ExampleExcluded Lots

Pay Equations for Pavement Ride Quality for 0.01 Mile

Route 00 NBMP 5.0 to MP 10.0

----------------------Route 00 SBMP 10.0 to MP 5.0

1 in Lane 13 in Lane 2

-------------2 in Lane 115 in Lane 2

IRI < 28 PA = $50

28 < IRI < 48

PA = $120.00 – ($2.5 x IRI)

48 < IRI < 58

PA = $0

58 < IRI < 128

PA = (IRI – 58) x (– $7.1429)

IRI > 128 Remove & Replace

Asphalt Binders for Performance Based MixesWhen the specification for a mix is based on

performance testing of the mix (e.g., BRIC, BRBC, BDWSC), the actual binder needed will depend on the mix design.

A minimum grade binder is listed in the specification, but the precise binder that will be needed will depend on the mix design, the formulation of the binder, and the performance testing of that mix.

Asphalt Binders for Performance Based MixesWith an optimized mix design, a less modified

binder may work, but a more modified binder may be needed if the mix design is not optimum.

HMA Supplier should work with the Binder Supplier to develop a mix that will meet all performance testing for the mix.

Performance Based Specifications ResearchNew research project starting this year to

look at the following:Existing NJDOT performance based mix

requirements.Performance based specifications for “regular”

mixes.Use of performance based specifications to

eliminate prescriptive aspects of NJDOT specifications.

Research being done by Rutgers.Research is expected to last 2 years.

RAP in HMA Research ProjectStudy being done by Rowan University.2 year study will be complete July 2011.Findings to date:

There is incomplete blending of the RAP binder with the virgin binder. Only partial credit should be considered for the RAP binder.

Quality Control is important. Amount of RAP allowed should be linked to variability of the RAP stockpile.

Northeastern States’ RAP Pooled Fund StudyMany of the Northeastern States (including

NJDOT) are involved in a Pooled Fund Study looking at use of higher percentages of RAP (>25%).

Work being done at University of New Hampshire with assistance by Rutgers University.

Thank you for your attention!eileen.sheehy@dot.state.nj.us