Performance Related Specifications for Concrete

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SOLVING PROBLEMS OF GLOBAL IMPORTANCE

© 2015 Applied Research Associates, Inc. 1 © 2014 Applied Research Associates, Inc.


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101st Annual Transportation Highway Engineering Conference 24 Feb 15

Performance Related Specifications for Concrete

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© 2015 Applied Research Associates, Inc. 2 © 2014 Applied Research Associates, Inc. www.ara.com 2

Specifications have different risk profiles R

isk

100

QC/QA Method

Type of Specification

0 End-Result Performance/

Warranty

Contractor

Owner

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© 2015 Applied Research Associates, Inc. 3

PRS

Warranties 1960 1970 1980 1990 2000 1950 1940 1930

1920 1910

2000

QA Specifications

Method Specifications

Warranties

1970

1935

1915

Construction specifications have evolved

4

Identify AQCs and Target Values

Establish Performance Criteria

Model ME Performance

Design AQC vs. As-Constructed AQC

Compare As-Built and As-Designed

Pay Factor f(ΔLCC) Time

LCC

,s

Design

Constructed

PAVESPEC

M&R Plan

How PRS Works Planning

Pavement Design

Pavement Construction, Sampling, and Testing

Incentive and Disincentive Pay

Incorporate Pay Tables Into Specifications & Project Letting

Use Specifications

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PRS applied to larger paving projects

 Project would have at least 10 sublots  Will be evaluated and determined by Tollway  Pay factors will be different by corridor

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Pavement type selection report is the PRS basis

  Traffic

  Design

  Reliability & Performance Criteria

  Support conditions

  M & R strategies

  Costs & other miscellaneous data

7

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Design Life Cycle Cost As-Built Life Cycle Cost

Pavement Life Cycle Cost Model

0 5 10 15 20 25 30 35 40 45 50

$$$

0 10 20 30 40 50

$$$

0 10 20 30 40 50

$$$

0 5 10 15 20 25 30 35 40 45 50

$$$

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First define Acceptance Quality Characteristics

 Measureable • More rapid the better

 Correlate with performance • Prediction models

 Are under contractor’s control • Can be varied on the project

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 Five AQCs • Compressive strength • Air • Thickness • Smoothness • Dowel Alignment

 Each has • Target • Rejectable level • Maximum level

Acceptance Quality Characteristics (AQCs)

All AQC tests MUST be tested with random sampling

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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

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Examples of Important Definitions

2,500

3,000

3,500

4,000

4,500

5,000

5,500

6,000

6,500

7,000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 Lot Number

Com

pres

sive

str

engt

h, p

si Maximum Quality Level (MQL)

Rejectable Quality Level (RQL)

Target

15

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Examples of Important Definitions

2,500

3,000

3,500

4,000

4,500

5,000

5,500

6,000

6,500

7,000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 Lot Number

Com

pres

sive

str

engt

h, p

si

80

85

90

95

100

105

110

Strength pay factor, percent

Maximum Quality Level (MQL)

Rejectable Quality Level (RQL)

Target

15

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Lots and Sublots

 Lot: All mainline concrete

 Sublot: Division of a lot for testing and sampling • One lane wide and ~1,000 ft. long (Generally 700 – 1,300 ft.) • Provisions for pavement blockout

• Access areas, bridge approach, ramp transition, etc.

 Sublot limits marked on plans (by lane)

 Payment is made on lot basis

 Rejection is made on sublot basis

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Random sampling is a key requirement

 Every sublot has equal weight  Random number generator to determine sample location  Random locations determined before each paving day

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Non-conforming Materials - revised

 If RQL not met, contractor to develop Corrective Action Plan  No incentive/disincentive for a sublot with non-conforming materials.  Accept or reject concrete on a sublot basis.

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28-Day Compressive Strength

 Test with cylinders (Illinois Modified AASHTO T22, T23)

• Process described in IDOT Article 1020.09 Strength Tests

• 6”x12” cylinders only  Two cylinders per sublot

Level Mean (psi) Std. Dev. (psi) Target 5,500 500

Rejectable 4,000 - Maximum 6,500 -

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Strength pay factor curve

85

90

95

100

105

4,000 4,500 5,000 5,500 6,000 6,500

Pay

Fact

or, %

28-Day Compressive Strength, psi

Std. Dev. = 500 psi

Std. Dev. = 1,000 psi

Std. Dev. = 0 psi

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Air Content

 Test with pressure meter according to IDOT Article 1020.08 Air Content

 Computed from average of four tests per sublot

• Same samples used for strength cylinders + 3 others

Level Mean Content (%)

Standard Deviation (%)

Target 6.5 0.5 Rejectable 5.0 - Maximum 9.0 -

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Air content pay factor curve

85

90

95

100

105

5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0

Pay

Fact

or, %

Entrained Air Content, %

Std. Dev. = 0.5Std. Dev. = 1.0Std. Dev. = 0

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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

Level Mean (in.) Std. Dev. (in)

Target Plan thickness 0.25 Rejectable Plan thickness - 0.5 - Maximum Plan thickness + 1.0 -

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Slab thickness pay factor curve

85

90

95

100

105

12.50 12.75 13.00 13.25 13.50 13.75 14.00

Pay

Fact

or, %

PCC Thickness, in

Std. Dev. = 0.25 inStd. Dev. = 0.50 inStd. Dev. = 0 in

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Smoothness (IRI)

 Test in accordance with ASTM E950 • Class I inertial profiler

 Test and report each wheel path

 Computed from average of wheel paths

Level Mean (in./mile) Std. Dev. (in./mile) Target 60.0 10.0

Rejectable 80.0 - Maximum 50.0 -

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Smoothness pay factor curve

85

90

95

100

105

50 55 60 65 70 75 80

Pay

Fact

or, %

IRI, in/mi

Std. Dev. = 10 in/miStd. Dev. = 20 in/miStd. Dev. = 0 in/mi

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Effective Dowel Diameter (EDD)

 Test with MIT-Scan 2

 Calculate EDD as described in NCHRP Report 637

 Averages of five consecutive joints

 Rejection on individual alignment criteria

 Process control separate of PRS

Level Mean (in.) Std. Dev. (in.) Target 1.50 N/A

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Effective dowel diameter pay factor curve

85.0

90.0

95.0

100.0

105.0

1.35 1.40 1.45 1.50

Pay

Fact

or, %

Effective Dowel Diameter, in

Std. Dev. NA

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PRS Example Project

 3 random Lots selected  Tested For

• 28 Day Compressive Strength • Slab Thickness • Air Content • Smoothness • Effective Dowel Diameter

 Individual and Composite Pay Factors (PF) calculated

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28-day Compressive Strength - Proposed

3,500 4,000 4,500 5,000 5,500 6,000 6,500 7,000 7,500

Lot 1

Lot 2

Lot 3

28-day Compressive Strength, psi

RQL Target MQL

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Air content example

4.00 4.50 5.00 5.50 6.00 6.50 7.00 7.50 8.00 8.50

Lot 1

Lot 2

Lot 3

Air Content, percent

RQL Target MQL

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Slab thickness example

10.00 10.25 10.50 10.75 11.00 11.25 11.50 11.75 12.00 12.25

Lot 1

Lot 2

Lot 3

Slab Thickness, in

RQL Design MQL

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Smoothness example

40.00 50.00 60.00 70.00 80.00 90.00 100.00

Lot 1

Lot 2

Lot 3

Initial IRI, in/mi

RQL Target MQL

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Effective dowel diameter example

1.10 1.20 1.30 1.40 1.50

Lot 1

Lot 2

Lot 3

Effective Dowel Diameter, in

Target

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Lot Composite Pay Factors

Maximum Composite PF: 105% Minimum Composite PF: 85%*

100100100100100100

⋅

⋅

⋅

⋅

= dowelsmththkairstr

lotPFPFPFPFPFPF

*Provided AQCs meet the RQL standards

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PRS Evaluation for 2013 projects

 Using Example PRS • Maximum pay – 105.3% • Minimum pay 93.3% • Average pay – 99%

 We are achieving this quality

level with current practice!

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Spreadsheet to track PRS data

 Will calculate pay factors even with partial data

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Performance-Related Specifications (PRS) benefit Tollway, consultants, and contractors

 Pavement design basis for construction performance

  Incentives and disincentives based on LCCA

 Contractors can innovative be competitive

 No long-term monitoring and management

 Testing focuses on key characteristics

• Measureable • Related to performance

37

Thank You

William R. Vavrik, Ph.D., P.E. Vice President & Principal Engineer Applied Research Associates, Inc. 100 Trade Centre Dr., Ste 200. Champaign, IL 61820 (217) 356-4500 [email protected]

Documents

Performance Related Specifications for Concrete