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How many tons of concrete were recycled across the entire Tollway in 2014?

540,000

58%

Performance Specifications for Tollway Roadway Construction –

Vision of the Future

Steve Gillen

Specifications Have Different Risk Profiles

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Owner/Designers

Contractor

0

100

Method QC/QA End-Result Performance/

Warranty

Type of Specification

Construction Specifications Have Evolved

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PRS

Warranties

1960 1970 1980 1990 2000

1950

1940

1930

1920

1910

2000

QA Specifications

Method Specifications

Warranties

1970

1935

1915

Prescriptive PCC Patching Mixtures Replaced With Performance Based Mixes in 2008

Strength is significantly overdesigned with prescriptive specs

Not enough emphasis on durability with prescriptive specs

High cracking potential with prescriptive specs

Needs for performance- based specification: Adequate strength, maturity

based

Good durability

Eliminated cracking

Revised Performance Requirements For Patch Mixes

Compressive Strength (ASTM C 39)

Opening to traffic: 2850 psi @ 20 hrs or 4000 psi @ 48 hrs.

Acceptance and payment: 3500 or 4000 psi @ 14 days

Time to cracking (ASTM C 1581) : 10 days

Freeze-thaw (ASTM C 666 Proc. A): 300 cycles, RDM ≥ 80%

Drying shrinkage: 0.05% @ 28 days

Chloride permeability: 2000 Coulombs @ 28 days (accelerated)

Alkali-Silica Reactivity (ASTM C1293): <0.04% ONLY if alkali > 5.0 lb/yd3

Air void system (ASTM C 457): 0.008-in, 600 in2/in3, 4.0%

Condition of Tollway Crack Resistant High Performance Concrete Bridge Decks

In 2012, CTL Group Laboratories researched and developed Tollway performance related specifications for crack resistant high performance concrete (HPC) bridge deck concrete using local materials in plant produced and lab produced mixes

Enhances sustainability

Minimizes cracking of the decks

Improves the resistance to chloride penetration

Provides adequate freeze thaw resistance

Test Method Performance Requirement Time, days

AASHTO T 22-10 4000 ≤ f’cr ≤ [f’cr + 1500] psi at 14 days 14

AASHTO T 119 Slump greater than 3" for 45 minutes

after water added to cement 1

ASTM C1581-09a

(Ring Test)

Minimum 28 days with no cracking

Exempt when less than 600 lb/yd3 cementitious

and a minimum of 1.5 gal/yd3 SRA is used

28 (0)

AASHTO T 160-09

(Length Change)

Maximum 0.03 percent after

7 days curing and 21 days drying, zeroed at the start of drying 28

AASHTO T 161(A)-08

(Freeze/Thaw Mod.)

Minimum RDM of 80 percent after 300 cycles

Exempt if ASTM C457 requirements are met and

aggregate is IDOT Class A+

74 (7)

AASHTO T 303

(Alkali Reactivity)

Expansion less than 0.10% at 16 days

Exempt if total alkali content from cement is less than 4

lb/yd3

16 (7)

ASTM C457-11

(Hardened Air)

Spacing factor not exceeding 0.008-in

Specific surface not less than 600 in2/in3

Total air content not less than 4.0%

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AASHTO T 277-07

(Cl Penetration) Max 1250 C after 28 day accelerated curing 28

Performance Requirements for HPC Deck Mixes

Success of Tollway Crack Resistant HPC Mixes Developed Through Research

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Not a single shrinkage crack to be found in the 28 I-90 bridge decks constructed in 2013 and 2014 with Tollway HPC concrete

Can we further improve it to produce 75 year life bridge decks without the need for stainless steel?

All Future Pavement Construction to Use Only Peformance Related Optimized Ternary Mixes

Between 2014 and 2026, more than a million cu. yds. of performance related ternary pavement mixes (Class TL) to be produced for new Chicagoland expressways

Mixes will require a minimum of 35% SCM’s

Blended cements allowed to optimize gradation

Feed of washed chips is mandatory

More than 500,000 cu yds to be placed on I-90 in 2015 & 2016

Performance Requirements For Pavement Mixes

Compressive Strength (ASTM C 39)

Opening to traffic: 2500 psi @ 3 days (425 psi flexural)

Ultimate: 3500 psi @ 14 days (650 psi flexural)

Target: 5500 @ 28 days age

Maximum: 6500 @ 28 days age

Plastic air: 5.5% - 8.0% for slip form; 5.0% - 8.0% for manual

Hardened air: (ASTM C457): 0.008-in., 630 in2/in3, 4.0%

Slump: Contractor’s choice for slip form, 2”– 4” for manual

Alkali-Silica Reactivity (AASHTO T 105): not to exceed 5.0 lb/yd3 in portland cement

Air void system (ASTM C 457): 0.008-in, 600 in2/in3, 4.0%

PRS Applied to Larger Concrete Paving Projects Starting in 2015

Project would have at least 10 sublots

Will be evaluated and determined by Tollway

Pay factors will be different by corridor

Pavement Type Selection Report (LCCA) is the Construction PRS Basis

Traffic

Design

Reliability and Performance Criteria

Support conditions

M & R strategies

Costs and other miscellaneous data

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First Define Acceptance Quality Characteristics (AQC’s)

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Measureable

More rapid the better

Correlate with performance

Prediction models

Are under contractor’s control

Can be varied on the project x

Acceptance Quality Characteristics (AQCs)

Five AQCs

Compressive strength

Air

Thickness

Smoothness

Dowel Alignment

Each has

Target

Rejectable level

Maximum level

All AQC tests MUST be tested with random sampling

Levels of Pavement Quality

Target Quality Level (TQL)

At target 100% pay

Near target pay adjustment (incentive/disincentive)

Rejectable Quality Level (RQL)

Corrective measures required

Maximum Quality Level (MQL)

No further incentive

Example of How a Pay Factor is Measured

Slab Thickness

Test with MIT-Scan T2 meter as described by user manual

Random pre-determined locations

Computed from average of four measurements per sublot

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Slab Thickness Pay Factor Curve

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85

90

95

100

105

12.50 12.75 13.00 13.25 13.50 13.75 14.00

Pay F

acto

r, %

PCC Thickness, in

Std. Dev. = 0.25 in

Std. Dev. = 0.50 in

Std. Dev. = 0 in

PRS Evaluation on 2013 I-90 Projects

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Using Example PRS

Maximum pay – 105.3%

Minimum pay – 93.3%

Average pay – 99%

We are achieving this quality level with current practice!

Lot Composite Pay Factors

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100100100100100100

dowelsmththkairstr

lot

PFPFPFPFPFPF

Maximum Composite PF: 105%

Minimum Composite PF: 85%*

*Provided AQCs meet the RQL standards

Maximum Disincentive With Normal Variability

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*Minimum is 85%

Maximum Disincentive With Normal Variability

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*Maximum is 105%

Spreadsheet to Track PRS Data

Will calculate pay factors even with partial data

Data distributed to all through e-Builder

Benefits to Performance Specifications

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Improved design-to-construction communication

Develop more rational pay factors

Improved and focused testing by all parties

Improved tradeoff analyses

Improved understanding of performance by all

Improved quality focus

Clearer distinction in roles and responsibilities

Creates a more innovative environment

THANK YOU

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