Coarse Aggregate Selection for Improved Rigid Pavement Joint and Cracking Performance

Jeffery R. Roesler, Ph.D., P.E. and Punya Chupanit, Ph.D.

University of Illinois at Urbana-Champaign

CEAT Brown Bag Lunch SeminarOMP

Chicago, IL – May 5, 2005

Concrete Pavement Cracking

Concrete Pavement Joint Deterioration

RESEARCH OBJECTIVES

Improve concrete material’s mechanical properties for

rigid pavements by selecting the appropriate concrete

constituents

> Maintain high shear load transfer across joints

> Increase concrete slab cracking resistance / ductility

Joint Load Transfer Efficiency (LTE)

Good Load Transfer

L= 1 U= 0

Poor Load Transfer

L= 1 U= 1

LTE = U

L

LOAD TRANSFER ABILITY

FACTORS AFFECTING THE LOAD TRANSFER CRACK WIDTH AGGREGATE TYPE AGGREGATE SIZE AGGREGATE SHAPE AGGREGATE GRADATION CONCRETE STRENGTH METHOD & TIMING OF CONCRETE FRACTURE

CONCRETE JOINT PERFORMANCE

GOOD BAD Strong Aggregate × Weak Aggregate

(Nowlen-1968; Colley and Humphrey-1967; Abdel-Maksoud-1999; Wattar-2001; Jensen and Hansen-2001)

Large Aggregate × Small Aggregate

(White and Holley-1972; Walraven-1980; Laible et al-1977; Sutherland and Cashell-1945; Abdel-Maksoud-1999; Jensen and Hansen-2001)

Gap Gradation × Dense Gradation

(Bruinsma et al-1995; Abdel-Maksoud-1999; Wattar-2001)

Rough and Strong Surface × Smooth and Weak Surface

JOINT SHEAR TESTING

EXPERIMENTAL SETUP

PREVIOUS JOINT SHEAR TESTING RESEARCH AT UIUC CONCRETE TEST SPECIMENS BY

ABDEL-MAKSOUD(1999) AND WATTAR(2001)

JOINT SHEAR STIFFNESS(Abdel-Maksoud-1999;Wattar-2001)

CONCRETE MATERIAL COMPOSITION

Concrete Mix Design Nomenclature (25GRG)

Aggregate Size, e.g., 25 or 38 mm

Gap Graded = G Dense Graded = D

River Gravel = RG Limestone = LS Trap Rock = TR

Aggregate Composition

CompositionLimestone Trap Rock

River Gravel

1

River Gravel

2

River Gravel

3SiO2 (%) 9.51 48.57 96.04 3.70 3.54Al2O3 (%) 2.31 17.42 1.40 1.72 1.66Fe2O3 (%) 1.86 13.15 1.65 1.27 0.29K2O (%) 0.80 1.19 0.18 0.15 0.21CaO (%) 52.25 9.48 0.21 54.99 88.23MgO (%) 33.03 5.84 0.41 37.40 5.09Na2O (%) 0.01 2.27 0.00 0.00 0.00TiO2 (%) 0.02 1.66 0.05 0.06 0.05P2O5 (%) 0.05 0.18 0.03 0.06 0.04MnO (%) 0.09 0.16 0.02 0.48 0.04

CONCRETE MATERIALS

Mix Number 25GRG 38GRG 25DRG 25DTR 38GTR 25DLS

Type I Cement(kg/m3)

335.4 335.4 335.4 335.4 335.4 335.4

Fine/Sand (kg/m3) 741.1 741.1 741.1 741.1 741.1 741.1

Coarse aggregate(kg / m3)

1198.0 1198.0 1198.0 1198.0 1198.0 1198.0

Water Content(kg / m3)

165.2 165.2 177.0 165.2 165.2 171.6

W/C ratio 0.49 0.49 0.53 0.49 0.49 0.51

AggregateType

RiverGravel

RiverGravel

RiverGravel

TrapRock

TrapRock

Limestone

Max. Size 25mm 38mm 25mm 25mm 38mm 25mm

Agg.Gradation Gap Gap Dense Dense Gap Dense

Mix Number 25GRG 38GRG 25DRG 25DTR 38GTR 25DLS

f’c at 10-12 hrs(MPa) 4.0 3.9 4.1 4.0 3.8 4.2

f’c at 28 days(MPa) 33.8 31.7 33.8 33.6 32.2 38.1

CONCRETE COMPRESSIVE STRENGTH

JOINT SHEAR STIFFNESS(Wattar-2001)

Mix IDCrack

Opening (mm)

AVG. Joint Stiffness

(MPa/mm)

25GRG 2.0 0.793

38GRG 2.0 1.187

25DRG 2.0 0.708

25DTR 2.0 0.825

38GTR 2.0 1.094

25DLS 2.0 0.616

EXPERIMENTAL SETUP OF CRACK

SURFACE CHARACTERIZATION

CONCRETE CRACK SURFACES

NON-CONTACT LASER PROFILOMETER

SCANNED SURFACE

STEPPING MOTOR

SYSTEM FRAMESTEPPING MOTOR

LASER SENSOR

Concrete Surface Re-creation

Actual surface Scanned surface

50mm Trap Rock Surface

Concrete Surface Characterization Roughness

Surface Roughness Volumetric roughness

Fractals or degree of irregularity

Power Spectral Area Parameter (PSAP)

Surface Roughness Parameter

areasurfaceprojecteds

areasurfaceactualRs

Areasurfaceprojected

volumevoidandtextureVSTR

Volumetric Surface Texture Ratio (VSTR)

(Vandenbossche-1999)

FRACTAL DIMENSION

Mix ID Fractal Dimension

25GRG 2.247

38GRG 2.245

25DRG 2.267

25DTR 2.264

38GTR 2.233

25DLS 2.255

SENSITIVITY INDEX = 1.33%

Can’t predict joint stiffness

Fractal Dimension to Characterize Crack Surfaces

SURFACE ROUGHNESS PARAMETERS FRACTAL DIMENSION

POWER SPECTRAL AREA PARAMETER (PSAP) BASED ON 2D FOURIER TRANSFORM DEFINED AS AREA UNDER POWER SPECTRUM

(Carpinteri et al-1999)

POWER SPECTRAL AREA PARAMETER (PSAP)

BASED ON 2D FOURIER TRANSFORMDEFINED AS AREA UNDER POWER SPECTRUM

xKA

xKAxKAAxf

nn

o

sin...

sinsin)( 2211

Power Spectrum

Power Spectral Area Parameter (PSAP) Determination

1

0

1

0

/)22(,

2

, 2

N

n

N

m

Nmqnpimnqp ehH

2D Fourier Transform

PSAP Calculation

jN

iqp

jj H

NS

1

2

,

12D Mean Spectral density (mm3/cycles)

jN

K j

2

Radial Wave Number (cycles/mm)

PSAP DETERMINATION

The cut-off wave number separates the large amplitude surface components from the small amplitude surface components

PSAP is defined as the area under the 2D mean power spectrum from non-zero wave number up to 0.0666 cycles/mm.

PSAP Results and Correlation with Joint Stiffness

Radial wave number

Number of Component *

25GRG 38GRG 25DRG 25DTR 38GTR 25DLS R2-VALUE

0.067 3 16.22 20.39 17.04 17.29 20.96 16.14 0.875

0.111 5 20.27 25.22 21.47 21.56 26.32 20.23 0.843

0.178 8 24.13 28.94 25.33 25.48 30.37 23.73 0.839

0.222 10 25.63 30.37 26.91 27.01 32.08 25.14 0.823

0.289 13 27.22 31.85 28.69 28.73 33.84 26.68 0.797

0.333 15 27.99 32.57 29.58 29.57 34.69 27.43 0.782

0.400 18 28.85 33.45 30.59 30.51 35.69 28.33 0.766

0.555 25 30.21 34.89 32.23 32.03 37.30 29.74 0.742

0.666 30 30.89 35.62 33.05 32.78 38.12 30.45 0.730

1.066 48 31.04 35.13 32.99 32.39 38.40 31.00 0.655

* The PSAP does not include the zero radial wave number component

PSAP DETERMINATION

PSAP Results

Scale Independent, Better Predict Shear Load Transfer, Valid with Different Aggregates.

PSAP predicts load transfer ability across cracks/joints

Roughness Parameter Summary

Surface Parameter

Correlation with Joint Stiffness

UniqueSensitivity Index %

Rs 0.437 No 5.0

VSTR 0.128 No 27.7

Df 0.476 Yes 1.3

PSAP 0.875 Yes 23

How can we characterize concrete

surface roughness / shear stiffness?

CONCRETE FRACTURE ENERGY

Beam Fracture Testing

a0D

P

S t

WEDGE SPLITTING TEST (WST)

(Linbauer and Tschegg-1986)

Fracture Energy (GF) Definition

Load vs Displacement

0

500

1000

1500

2000

2500

3000

3500

4000

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1CMOD (mm)

Lo

ad

(N

)

ft

GF = Area or Work of Fracture Cracked Area

GF determination from WST test

max1 ][][tan2

1 ht

mgeFunderArea

ht

dCMODFunderArea

htG vv

WF

Fracture Energy Results

Mix IDGF

at 12 hrs

GF

at 28 days

38GTR194.5 566.2

38GRG145.8 573.3

25DTR114.4 384.9

25GRG89.1 252.3

25DRG87.8 208.8

25DLS52.7 93.7

AVG. Joint Stiffness (MPa/mm)

1.094

1.187

0.825

0.793

0.708

0.616

Effect of Concrete Material Properties

on Surface Roughness, Crack Resistance

and Shear Load Transfer

GF and Shear Load Transfer

•Shear load transfer depends on GF at 28 days.•Concrete with high GF at 28 days provides good shear load transfer across cracks/joints.

AGGREGATE TYPE (25mm)

1) TRAP ROCK 2) RIVER GRAVEL 3) LIMESTONE

AGGREGATE GRADATION

Aggregate gradation doesn’t have much impact.

AGGREGATE SIZE

LARGE BETTER THAN SMALL (38MM) (25MM)

Other significance of GF

GF better characterize the effect of Coarse Aggregate on concrete cracking performance.

f’c (12 hrs) = 3.8 – 4.2 MPa

GF (12 hrs) = 52.7 – 194.5 N/m

f’c (28 days) = 31.7 – 38.1 MPa

GF (28 days) = 93.7 – 573.3 N/m

CONCLUSIONS

Power Spectral Area Parameter (PSAP) indicates surface roughness and predicts shear stiffness across crack/joint.

GF at 12 hours and 28 days can represent the concrete cracking resistance at early and mature ages

Aggregate type and size primarily influence joint shear stiffness (PSAP) and concrete cracking resistance (GF).

CONCLUSIONS

Concrete with large, strong aggregates perform better than concrete with small, weak aggregates.

Design of concrete materials should use more than flexural/compressive strength to quantify material behavior (GF).

Maintain small crack widths (<1.5 mm)

Concrete Mix Design Update

0.75"688.38.ST 688.38 688.44 588.38 588.44

w/cm 0.38 0.38 0.44 0.38 0.44water (lb/yd^3) 262 261 303 217 251cement (lb/yd^3) 588 588 588 488 488fly ash (lb/yd^3) 100 100 100 83 83CA (lb/yd^3) 1850 1842 1772 1982 1924FA (lb/yd^3) 1103 1083 1042 1166 1132AEA (oz/yd^3) 14 14 16 16 16WR (oz/yd^3) - - - 7 7

Course Aggregate Top Size

1.5"

Variable Values Aggregate Size 0.75" or 1.5"

W/CM 0.38 or 0.44 Cement Content 488lb/yd3 or 588lb/yd

Total aggregate content Varies

Concrete Strength Results

Air (%) UW (lb) Slump (in) fc' 7 (psi) fr 7 (psi)Typical O'Hare Mix (CA 3/4")

w/cm = 688lb/yd3 w/c = 0.38 7 36.05 3.75 3690

Additional Laboratory Mixes (CA 1.5")

w/cm = 688lb/yd3 w/c = 0.38 6 36.70 4.75 3000

w/cm = 688 lb/yd3 w/c = 0.44 3 37.60 9 2720

w/cm = 588 lb/yd3 w/c = 0.38 5.5 36.75 3 2400

w/cm = 588 lb/yd3 w/c = 0.44 4 37.70 6 2280 768

Excepcted Values of Typical O'Hare Mix 5-8 - 3 +/- 1 ~6300

688.38688.44588.38

588.44

688.38.ST

QUESTIONS /COMMENTS