29th Annual Airport ConferenceFebruary 28 – March 2, 2006

Hershey, Pennsylvania

An IPRF Project Overview of Acceptance Criteria Based on Innovative Testing of Concrete Pavements

Soheil Nazarian, PhD, P.E. University of Texas at El Paso

Wayne Seiler, PhD, P.E. All About Pavements, Inc.

Overview

• Contractor and Technical Panel

• Goals, Limitation, and Objectives

• Selected Technologies

• Lab versus Field Process Summary

• Research Conclusions

• Recommendations

• Products

Contractor

• Contractor

– University of Texas at El Paso

– University of Illinois Chicago

– Applied Pavement Technology

– US Army Engineer Research and Development

Center

• Principal Investigator – Dr. Soheil Nazarian

Technical Panel

• Panel Chair: Mr. Jim LaFrenz

• Panel Members

– Mr. Kevin MacDonald, Cemstone Products

– Mr. Jeff Rapol, FAA

– Mr. Robert Taylor, ACPA

– Ms. Susan Winslow, Delta Airport Consultants

– Dr. Wayne Seiler, All About Pavements, Inc.

Goal

• Evaluate New and Innovative Technologies– Basis for new P-501 acceptance criteria– Implementation by the FAA– Implementation by other agencies with PCC

guide specifications

Limitations of Current Acceptance Methods and Criteria

• Precision of Flexural Strength Tests

• Time to Acceptance

• Lab-cured Specimens vs. Slab

• Coring Cost and Convenience

• Too Few Tests

Objectives

• Methods to better estimate PCC strength

• Use nondestructive methods to estimate

thickness

• Develop practical protocols for lab and

field testing

Selected Technologies

• Thickness– Impact-echo– Probing

• Strength– Maturity– Seismic – Combination

Motivation

Maturity Maturity

?Maturity Does not consider construction qualityMaturity Does not consider construction quality

Seismic

Seismic Can complement

Maturity: Calibration

Time

Tem

pera

ture

Datum Temperature (To)

Area = TTF

1. Prepare about a dozen Specimens

2. Conduct Maturity Tests

3. Conduct Strength Tests

4. Develop Strength/Maturity Relationship

0

2000

4000

6000

8000

0 5000 10000 15000 20000TTF, degree(C)-hr

Com

pres

sive

Str

engt

h,

psi

Maturity: Field

1000

2000

3000

4000

5000

6000

0 5000 10000 15000 20000 25000

TTF,hr*C

Com

pres

sive

Str

engt

h,ps

i Lab Established

Measured on Cores

Seismic: Calibration1. Use same specimens for maturity

calibration

2. Conduct Seismic Tests

3. Conduct Strength Tests

4. Develop Strength/Seismic Modulus Relationship

5. Develop Seismic Modulus/Maturity Relationship

Seismic: Field

Seismic Lab Test Setup

HammerAccelerometer

ASTM C-215

Seismic Field Tests:

Surface Wave MethodPortable Seismic Pavement Analyzer

Sampled to this depth

Amplitude

Depth

Sampling Depth is Controlled by source

Can specify tmin and tmax

tmin

tmaxSampled to this depthSampled to this depth

Amplitude

Depth

Amplitude

Depth

Sampling Depth is Controlled by source

Can specify tmin and tmax

tmin

tmax

Can specify tmin and tmax

tmin

tmax

tmin

tmax

Thickness Determination Objectives

• Test methods are sufficiently accurate

• Construction-related parameters do not significantly impact the accuracy

– Texture (groove pattern) of the slab.– Type of material underlying the slab.

• Test methods are robust, repeatable, and reproducible.

Methods Considered

• Probing Fresh Concrete

– Not effective

• Impact Echo

10”

20”

32’

4’ 4’

4’ 4’

4’ 4’ 8’

2” 2”

2” 2”

2”

10”

b)

Long Slab for Thickness Measurement

Strength Determination Objectives

1. Laboratory relationships can be accurately developed between strength and Maturity and/or Seismic Modulus (UIC, ERDC, UTEP)

2. Changes in mixture-related parameters do not significantly impact the laboratory relationships (UIC, ERDC, UTEP)

3. Field and laboratory developed relationships are similar (ERDC, UTEP)

4. Test methods are robust, repeatable, and reproducible.

Materials

• UIC (Limestone): Lab Testing

• ERDC (Granite): Lab and Slab (Controlled Environment)

• UTEP (SRG): Lab and Slab (Actual Environment)

Parameter This StudyUTEP ERDC UIC

Slab Specimen Slab Specimen Slab Specimen

Cement content

Three LevelsAs designedGreater than designLess than design

Water-cement ratio

Three LevelsAs designedGreater than designLess than design

Air content

Three LevelsNo Air-entrainerLow Air-entainerHigh Air-entrainer

*

Type of Aggregates

Three LevelsSiliceous River GravelLimestoneGranite

% total aggregates

Three LevelsAs DesignedHighLow

Coarse Aggregate Fraction

Three LevelsAs designedGreater than designLess than design

Finess Modulus

Three LevelsAs designed5% Passing Sieve #5025% passing Sieve #50

* a database with similar parameter is available and will be used in the final analysis

Agg

rega

tes

Str

engt

h-R

elat

ed A

ctiv

itie

s-M

ater

ial

Methodology for Calculation of PWL

• Find sample average X for n specimens.X = (x1 + x2 + x3 + . . .xn) / n

• Find standard deviation Sn

Sn = [((x1 – X)2 + (x2 – X)2 +. . .(xn – X)2) /(n–1)]0.5

• For single sided specification limits (L), compute the Lower Quality Index QL :

QL = (X – L) / Sn

• Estimate PWL from QL and the corresponding n value.

Develop regression correlations between PWL of seismic modulus and flexural strength

y = 33.2e0.0098x

R2 = 0.9362

50

55

60

65

70

75

80

85

90

95

100

50 60 70 80 90 100

Existing PWL

Sei

smic

PW

L

a) Flexural Strength

50

55

60

65

70

75

80

85

90

95

100

50 60 70 80 90 100

Existing PWL

Sei

smic

PW

L SRG

Granite

Limestone

Global

a) Flexural Strength

SRG

All Mixes

Field Testing: Installation of I-buttons

Field Testing: Day of Paving

Field Testing

Research Conclusions

• The strengths measured on lab-cured cast cylinders and beams are different than those measured from cores and beams extracted from slabs

• The flexural strength of the top half of the slabs are normally less than the lower half of the slabs, especially in the early ages.

Research Conclusions

For the maturity method, relationships between flexural (or compressive) strength and maturity can be established with confidence in the laboratory.

The laboratory strength-maturity relationships are affected by the change in the mix proportions, especially by the cement content and water cement ratio.

If the maturity method is used alone, a rigid process control is needed to ensure that the lab-developed calibration relationship can be used with confidence in the field.

Research Conclusions

For the seismic method, laboratory relationships between the strength and seismic modulus can be developed with confidence.

The seismic-based strength-modulus relationships are much less sensitive to the mix proportions than the maturity relationships.

Again, process control during mixing is desirable.

Research Conclusions

The seismic moduli measured on the slab with PSPA generally correspond well with the seismic moduli measured with the FFRC on cores and beams extracted from the same slab.

The PSPA moduli are generally lower than FFRC moduli, because the PSPA is more sensitive to the properties of the top half of the slab.

Research Recommendations

Do not use Impulse Echo for P-501 Thickness Acceptance Testing

On a trial basis, use Maturity and Seismic Testing for Flexural Strength Acceptance Testing

IPRF Products Protocol for Laboratory and Field Testing

(Regenerated from TXDOT)

PSPA Training Materials

Shadow P-501 specification with alternate acceptance testing methods and procedures

Executive Summary report for general use