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