Transcript Document

Progress Report on Concrete
Mix Designs for
O’Hare Modernization Plan
University of Illinois
Department of Civil and
Environmental Engineering
July 14, 2005
Project Goal
Investigate cost-effective concrete properties
and pavement design features required to
achieve long-term pavement performance at
Chicago O’Hare International.
Project Objectives
Develop material constituents and proportions
Characterize strength, volume stability,and
fracture properties of airfield concrete mixes
Develop / improve models to predict material
behavior.
Evaluate material properties and structural design
interactions, e.g.,
joint spacing
joint types
Saw-cut timing
Project Objectives
Material
constituents and
mix design
Laboratory tests
Test for material
properties
Analysis of existing
concrete mix designs
Concrete properties
Modeling
Optimal joint types
and spacing.
Long-term
performance at
ORD
2005 Accomplishments
Tech Notes (TN)
TN2: PCC Mix Design
TN3: Fiber Reinforced Concrete for Airfield Rigid
Pavements
TN4: Feasibility of Shrinkage Reducing Admixtures for
Concrete Runway Pavements
TN11: Measurement of Water Content in Fresh
Concrete Using the Microwave Method
TN12: Guiding Principles for the Optimization of the
OMP PCC Mix Design
TN15: Evaluation, testing and comparison between
crushed manufactured sand and natural sand
TN16: Concrete Mix Design Specification Evaluation
TN17: PCC Mix Design Phase 1
TN2: PCC Mix Design
Mix Id.
Water
Type I Cement
Type C Fly Ash
Coarse aggregate (# 57
Limestone, 1" max size. )
Fine aggregate
Steel Fibers
Air entrainment admixture
(Excel Air)
Water Reducer (Excel Redi
Set)
Properties
W/CM
fr7
fr28
Air
Slump
Proposed
Mix #1905
(2000)
280
541
135
Revised
Mix #1905
(2000)
262
588
100
Proposed
Mix #1933
Mix #1994
(2000)
(2000)
280
262
588
588
100
130
Mix K-5
003Units
00(2004)
258
lb/yd3
541
lb/yd3
135
lb/yd3
1850
1850
1850
1800
1840
lb/yd3
1125
0
1103
0
1115
0
1100
85
1117
0
lb/yd3
lb/yd3
N/A
7
N/A
N/A
6.8
oz/yd3
29
15
28
29
30.4
oz/yd3
Proposed
Mix #1905
0.41
N/A
N/A
5-8
2
Revised
Mix #1905
0.38
788
1030
5-8
3 +/- 1
Proposed
Mix #1933 Mix #1904
0.41
0.36
802
N/A
842
N/A
5-7
5-8
3 +/- 1
3 +/- 1
Mix K-5
003-00
0.38
770
855
6.2
1
Units
psi
psi
%
in
Survey of Existing Mixes
Airport
Capital
Airport
St. louis
Lambert
St. louis
Lambert
Mix Id.
N/A
Mix 1 F
Mix 4 F
Water
Cement
Type C Fly Ash
GGBS
Coarse aggregate #1
Coarse aggregate #2
Fine aggregate
Fibers
Air entrainment admixture
Water Reducer
233
490
150
1842
1156
N/A
19.6
250
510
80
1866
1225
5.6
14.2
258
535
80
1834
1220
5.6
14.2
St. louis
Lambert
Mix 4 F
w/ fibers
258
535
80
1834
1220
3
5.6
14.2
I
I
I
I
Materials Properties
Cement Type
Coarse aggregate # 1 max.
size. (in)
Coarse aggregate # 2 max.
size. (in)
Fine aggregate type
AEA type
WR type
Fiber type
Concrete Properties
W/CM
fr28
Air
Slump
N/A
-
3/4" (#67) 3/4" (#67)
-
River
Sand
Polychen
AEA Grace
AE VRC
Daracem
Polychen
Grace
MC 400
N/A
-
-
-
-
0.36
770
5.5
4 1/2"
0.42
1033
7.6
2"
0.42
850
7
3 3/4 "
Mix 3 F
Mix 5 F
248
354
88
148
1872
1228
3
17.7
258
310
93
217
1808
1232
3.1
18.6
St. louis
Lambert
Mix 5 F
w/fibers
258
310
93
217
1808
1232
3
3.1
18.6
I
I
I
St. louis
Lambert
St. louis
Lambert
Fort Californ Califor
Wayne
ia
nia
Mix 6 F
Mix P 5
Mix 1
Mix 1
Mix 2
258
372
93
155
1836
1206
3.1
18.6
250
680
1790
1280
N/A
N/A
218
288
192
1424
615
1198
N/A
N/A
300
489
122
1570
400
1165
N/A
N/A
258
479
85
1400
475
1310
1.7
16.92
I
I
I
I
II
1" (57)
1" (57)
3/4" (#67) 3/4" (#67) 3/4" (#67) 3/4" (#67) 3/4" (#67) 3/4" (#67) 1" (57)
-
River Sand River Sand
Polychen
AE VRC
Polychen
MC 400
St. louis St. louis
Lambert Lambert
Polychen
AE VRC
Polychen
MC 400
GRT
Polymesh
fibers
0.42
905
7
3 3/4 "
-
-
-
River
Sand
Polychen
AE VRC
Polychen
MC 400
River
Sand
Polychen
AE VRC
Polychen
MC 400
-
-
River
Sand
Polychen
AE VRC
Polychen
MC 400
GRT
Polymesh
fibers
0.42
700
5
1 1/4 "
0.42
675
5
3"
0.42
675
5
3"
-
-
River
River
Sand
Sand
Polychen
GRT AEA
AE VRC
Polychen GRT KB
MC 400 1000
lb/yd3
lb/yd3
lb/yd3
lb/yd3
lb/yd3
lb/yd3
lb/yd3
lb/yd3
oz/yd3
oz/yd3
1/2 x
#4"
N/A,FM N/A,FM Sechelt
= 2.68 = 2.96 Sand
3/8"
3/8"
N/A
N/A
MBAE
N/A
N/A
Pozz
200N
-
-
-
-
-
0.42
675
5
3"
0.37
1280
6
1 1/2"
0.45
N/A
N/A
N/A
0.49
N/A
N/A
N/A
0.46
767
3
3 1/4"
Units
psi
%
in
Tech Note 3
Fiber Reinforced Concrete for Airfield
Rigid Pavements
225
Plain
0.48% Synthetic Macro Fiber
200
0.32% Synthetic Macro Fiber
175
Load (kN)
150
125
100
75
50
25
0
0
1
2
3
4
5
6
7
8
9
10
11
12
Average Interior Maximum Surface Deflection (mm)
 Final cost: reduction of 6% to an increase of 11%
13
Tech Note 4
Feasibility of Shrinkage Reducing Admixtures
for Concrete Runway Pavements
Reduced Shrinkage and Cracking Potential ~ 50% reduction
Cost limitations (?)
Figure 1. Unrestrained shrinkage of mortar bars, w/c = 0.5 (Brooks et al. 2000)
Tech Note 11
Measurement of Water Content in Fresh
Concrete Using the Microwave Method
Strengths: quick, simple, and inexpensive
Limitations: need accurate information on
 cement content
 aggregate moisture and absorption capacity
TN 12: Guiding Principles for the
Optimization of the OMP PCC Mix Design
1st order:
Strength, workability
2nd Order:
Shrinkage, fracture properties
LTE & strength gain
Tech Note 15
Evaluation, testing and comparison between
crushed manufactured sand and natural sand
Gradation According to ASTM C-33
100
Manufactured Sand(ms)
Natural Sand(ns)
ASTM Fine
ASTM Coarse
80
PERCENTAGE PASSING.
Gradation
physical properties
Finness Modulus
ms = 3.12
ns = 2.64
60
40
20
0
200
100
50
30
16
8
4
0.375
ASTM SIEVE NUMBER
ASTM C-128
ASTM C-29
Material
BSG(ssd)
BSG(dry)
AC(%)
Manufactured sand
Natural sand
2.7
2.43
2.63
2.38
2.59
2.15
Bulk density Bulk density
dry(kg/m3) ssd(kg/m3)
1628
1703
1670
1740
% Voids
38.1
28.3
Manufactured vs Natural Sand
Visual evaluation
4mm
Material retained in
the #8 sieve shows
difference in the
particle shape
500mm
4mm
500mm
Sieve No. 8
Sieve No. 50
The Manufactured
sand shows a rough
surface and sharp
edges due to the
crushing action to
which it was
subjected.
Tech Note 16
Concrete Mix Design Specification
Evaluation
Preliminary P-501 evaluation
Strength, shrinkage, and material constituent
contents
P-501 Guidelines
Our View
max w/cm = 0.50
Ok
3
Min cement content = 500 lb/yd
This could be lower
min flexural strength = 600 psi @ 28 d 700 ok, could be 90 d
fly ash content range = 10-20%
Ok
fly ash + slag range = 25-55%
Ok
max slag when temp < 55 F = 30%
Ok
air content = 5.5% for 1.5" topsize CA
Ok
air content = 6.0% for 0.75" topsize CA
Ok
2005 Accomplishments
Specification Assistance
On-site meetings at OMP headquarters
Continued specification recommendations:
 Material constituents (aggregate type and size, SCM, etc.)
 Modulus of rupture and fracture properties of concrete
 Shrinkage (cement content, w/c ratio limits,etc.)
 Saw-cut timing, spacing and depth
 Pavement design
TN17: PCC Mix Design Phase 1
Develop mix design factorial and verify
fresh and hardened concrete properties
Variable
Aggregate Size
W/CM
Cement Content
Total aggregate content
More later …
Values
0.75" or 1.5"
0.38 or 0.44
3
488lb/yd or 588lb/yd
Varies
Project Tasks and Progress
Literature Review
Survey of existing mix designs
Review of mix design strategies
Status
Done,
TN2, 3, 4, 15
Done, TN 12
Volume Stability Tests
Drying and Autogenous shrinkage
Optimization of concrete mixes to
reduce volumetric changes
In progress,
TN 12 and TN 17.
Strength Testing
Modulus of rupture, splitting and
compressive strength
Fracture energy and fracture surface
roughness
In progress, TN
12 and TN 17
Start tests in July
Project Tasks and Progress
Joint Type Design
Slab size and jointing plans:
productivity, cost, performance.
Optimization of concrete
aggregate interlock to ensure
shear transfer.
Joint (crack) width prediction
model for concrete materials.
In progress, TN 3.
Requires fracture
results.
In progress,
TN 12.
Fracture tests
In progress, need
shrinkage/creep
results.
Project Tasks and Progress
Saw-cut timing and depth
Saw-cut timing criteria for
the expected materials
Analytical model / Validation
Review in progress,
requires fracture
results.
Fiber Reinforced Concrete
Materials
Overview of structural fibers
for rigid pavement
Literature
Review done,
TN 3.
PCC Mix Optimization – Phase I
Factor Levels
Three variables changed independently:
 Coarse aggregate top size
 ¾” and 1.5” top sizes
 Total cementitious content
 588lb/yd3 versus 688lb/yd3
 Water / cementitious ratios
 0.38 versus 0.44
Phase I was used to develop Phase II mixes.
PCC Mix Optimization – Phase I
Mix Design
Five mixes proposed to investigate 3 variables:
w/cm
water (lb/yd^3)
cement (lb/yd^3)
fly ash (lb/yd^3)
CA (lb/yd^3)
FA (lb/yd^3)
AEA (oz/yd^3)
WR (oz/yd^3)
0.75"
688.38.ST
0.38
262
588
100
1850
1103
14
-
Course Aggregate Top Size
1.5"
688.38
688.44
588.38
0.38
0.44
0.38
261
303
217
588
588
488
100
100
83
1842
1772
1982
1083
1042
1166
14
16
16
7
Water reducer was added as necessary
588.44
0.44
251
488
83
1924
1132
16
7
PCC Mix Optimization – Phase I
Results
Values within range for a typical O’Hare mix
Air (%)
UW (lb)
Typical O'Hare Mix (CA 3/4")
688.38.ST
7
36.05
Slump (in)
fc' 7 (psi)
3.75
3690
Additional Laboratory Mixes (CA 1.5")
688.38
6
36.70
4.75
688.44
3
37.60
9
588.38
5.5
36.75
3
588.44
4
37.70
6
3000
2720
2400
2280
fr 7 (psi)
fr 28 (psi)
768
790
PCC Mix Optimization – Phase II
Phase II mix objectives:
Mechanical Properties
 Meet specified strength, air content, workability, etc
 Maximize fracture resistance & ductility
Volume Stability
 Minimize shrinkage
Load Transfer
 Maximize aggregate interlock
PCC Mix Optimization – Phase II
Experimental Design
Primary factors of interest:
 Max. aggregate size, w/c ratio, cement content and
fly ash /cementitious ratio.
Agg. Size
W/CM
Fly Ash/CM
ID
MIX No.
0.75"
0.38
0.15
688.38.ST 688.38
1
2
1.5"
588.38
3
0.44
0.15
0.00
688.44 588.44 535.44
4
5
6
No water reducers are added in Phase II
0.18
455.44
7
PCC Mix Optimization – Phase II
Mix Design
Mixes identical to Phase I with the addition of two mixes to
investigate O’Hare specification extremes
w/cm
water (lb/yd^3)
cement (lb/yd^3)
fly ash (lb/yd^3)
CA (lb/yd^3)
FA (lb/yd^3)
AEA (oz/yd^3)
0.75"
688.38.ST
0.38
262
588
100
1850
1103
14
Course Aggregate Top Size
1.5"
688.38 571.38 688.44 571.44
0.38
0.38
0.44
0.44
261
217
303
251
588
488
588
488
100
83
100
83
1842
1982
1772
1924
1083
1166
1042
1132
14
16
16
16
No water reducers are added in Phase II
535.44
0.44
235
535
0
1984
1167
16
555.44
0.44
244
455
100
1942
1142
16
PCC Mix Optimization – Phase II
Testing
Fresh concrete properties
 Slump, Air Content, Unit Weight
Mechanical Testing
 Compressive strength at 7 and 28 days
 Modulus of Elasticity at 7 and 28 days
 Split tensile strength at 7 and 28 days
 Modulus of Rupture at 7 and 28 days
Stability Testing
 Drying and Autogenous Shrinkage trends for 28+ days
Fracture tests
 Early-ages (<48 hrs)
 Mature age (28 days)
PCC Mix Optimization
Preliminary Strength Summary
Compressive Strength (psi)
Mix
Age (days)
7
28
688.44
3367
4258
588.38
3525
3860
688.38
3361
3902
Splitting Strength (psi)
7
28
284
437
429
443
454
469
Toward a shrinkage specification
How much shrinkage is acceptable?
Little information in the literature
State of California Materials and Research Lab
 ASTM C157-64 used
 Three classes defined
 Class A: <320 microstrain
 Class B: <480 microstrain
 Class C: <640
Shrinkage over 735 microstrain is considered very
severe
Toward a shrinkage specification
Other recommendations
Non standard test:
8x8x2” specimens
Sealed 2 d, air dried 26
d, soaked 4 d, initial
measurement taken,
oven dried at 122 F and
17% RH
Building research station (UK), “Shrinkage of natural aggregates in concrete”, Build. Res. Stat. dig., no.
35, 1963.
Toward a shrinkage specification
Do we know exactly how much shrinkage is
acceptable?
Not exactly
 We know when a material is really bad and when a
material is really good
Bad materials should be avoided, and strategies
should be examined for approaching low
shrinkage concrete at minimal cost
PCC Mix Optimization – Phase II
Shrinkage Results
 All mixes show similar drying shrinkage
 As expected, mixes 688.44 and 688.38 that have a higher amount
of cementitious material (688 lb) show higher shrinkage compared
to mix 588.38 (588lb of cementitious material)
Experimental Shrinkage Data for all Mixes
688.44 Drying
688.38 Drying
0.5
Shrinkage (mm/m)
 The water cementitious ratio is not a
significant factor so
far.
0.6
588.38 Drying
0.4
0.3
0.2
0.1
0
0
5
10
15
20
25
Age of Concrete (days)
30
35
40
PCC Mix Optimization – Phase II
Shrinkage Results
 All mixes show similar drying shrinkage
 As expected, mixes 688.44 and 688.38 that have a higher
amount of cementitious material (688 lb) show higher
shrinkage compared to mix 588.38 (588lb of cementitious
material).
Experimental Shrinkage Data for all Mixes
0.6
688.44 Drying
Shrinkage (mm/m)
 The w/c ratio is not
a significant factor
so far.
688.38 Drying
0.5
588.38 Drying
0.4
0.3
0.2
0.1
0
0
5
10
15
20
25
Age of Concrete (days)
30
35
40
PCC Mix Optimization – Phase II
Shrinkage models vs. experimental results
ACI Model
Experimental
(688.38)
Experimental Data
Data vs.
vs. Shrinkage
Shrinkage Models
Models (588.38)
(688.44)
0.5
0.5
0.45
0.45
 Fine/Total agg.
 Entrapped air
 Volume/Surface
 Relative humidity
0.4
0.4
Shrinkage (mm/m)
Shrinkage
(mm/m)
 Cement content
0.35
0.35
0.3
0.3
0.25
0.25
0.2
0.15
Exp.
Exp. Total
Total
ACI
ACI Drying
Drying
0.1
0.05
FIB
FIB 2000
2000 Drying
Drying
0
0
5
10
10
15
20
25
30
35
Age of
of Concrete
Concrete (days)
Age
(days)
This model underestimates the experimental results
during the first 28 days for the mixes done so far.
40
PCC Mix Optimization – Phase II
Shrinkage models vs. experimental results
FIB 2000 Model
 Volume/Surface
 Relative humidity
 Type of cement
0.45
0.45
0.4
0.4
Shrinkage (mm/m)
Shrinkage
(mm/m)
 fc at 28 days
Experimental
(688.38)
Experimental Data
Data vs.
vs. Shrinkage
Shrinkage Models
Models (588.38)
(688.44)
0.5
0.5
0.35
0.35
0.3
0.3
0.25
0.25
0.2
0.15
Exp.
Exp. Total
Total
ACI
ACI Drying
Drying
0.1
0.05
FIB
FIB 2000
2000 Drying
Drying
0
0
5
10
10
15
20
25
30
Age of
of Concrete
Concrete (days)
Age
(days)
This model fits the experimental results during the
first 28 days for the mixes done so far.
35
40
Concrete Shrinkage Summary
- 1.5” max aggregate size
Concrete Age
Drying Age
MIX 588.38
MIX 688.38
MIX 688.44
1
0
0
0
0
*units in microstrain
3
2
107
118
112
7
6
213
233
235
14
13
303
338
332
28
27
367
405
412
Fracture Properties
The relationship between Fracture Energy and Joint
Performance
Fracture Energy is characterized using GF
The Shear Stiffness is a good indicator of Joint
Performance
Load vs Displacement
4000
3500
3000
Load (N)
2500
2000
1500
1000
500
0
0
0.1
0.2
0.3
0.4
0.5
CMOD (mm)
0.6
0.7
0.8
0.9
1
Fracture Properties
Wedge Splitting Test
Test configuration
 Low self weight effect
 Ideal for early age testing
 Similar to beam test
Load vs. CMOD curve
Load vs Displacement
4000
3500
3000
Load (N)
2500
2000
1500
1000
500
0
0
0.1
0.2
0.3
0.4
0.5
CMOD (mm)
0.6
0.7
0.8
0.9
1
Fracture Properties
Obtaining the Fracture Energy
Calculation of area under the curve
Load vs Displacement
4000
ft
3500
3000
Load (N)
2500
2000
1500
1000
500
0
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
CMOD (mm)
GF = Area under the Curve
Cracking Area
0.8
0.9
1
Fracture Properties
Effect of aggregate size on Fracture Energy
Larger coarse aggregate and higher Crushing
Value increase Fracture Energy
Fracture Properties
Effect of Aggregate Type on GF
Fracture Properties
Other significance of GF
GF better characterize the effect of coarse
aggregate on concrete performance.
For w/c = 0.49
 f’c (12 hrs) = 3.80 – 4.20 MPa
 f’c (28 days) = 31.7 – 38.1 MPa
 GF (12 hrs) = 52.7 – 194.5 N/m
 GF (28 days) = 93.7– 573.3N/m
Requirements for Saw-cut Timing
s
Stress
Strength
Time
Stress = f(thermal/moisture gradients, slab geometry,
friction)
Strength (MOR,E) and fracture parameters (Gf / KIC
cf / CTODc) with time
Saw-cut Timing and Depth
Notch depth (a) depends on stress, strength,
and slab thickness (d)
Stress = f(coarse aggregate,T, RH)
a
d
Tasks for FY 2006
PCC Mix Optimization
Fracture testing (finish Fall 2005)
Alternative cementitious materials/admix. (Phase III)
 FRC, HVFA, Slag
 Manufactured Sand (?)
Design and Construction Issues
Saw-cut timing (Dec. 2005)
Joint (crack) width prediction (Summer 2006)
Slab curling analysis* (Summer 2006)
Proposed New Ideas
Two-layer concrete pavements
Multi-functional rigid pavement
Cost saving
GREEN-CRETE
Recycled concrete aggregate
Effect of recycled aggregate on mechanical and
volumetric properties of concrete
Experimental pavement section and pavement
instrumentation
Multi-layer concrete pavements
Multi-functional rigid pavement:
Volume stability and fracture resistance
maximized independently
Skid resistance, aggregate interlock
Reduced slab curling
T,
RH
P
Functions
Wear Resistant
E(z), υ(z), α(z), k(z), ρ(z), D(z)
h
Shrinkage Resistant
Fatigue Resistant
z
Support Layers
h1, E1, υ1, α1, k1, ρ1, D1
No fibers
Porous Concrete Friction/Noise Layer
h2, E2, υ2, α2, k2, ρ2, D2
fB = 0.1%
Shrinkage Resistant Layer
h3, E3, υ3, α3, k3, ρ3, D3
fA = 0.25%
h4, E4, υ4, α4, k4, ρ4, D4
fA = 0.5%
Fatigue Resistant Layers
Support Layers
Preliminary Testing of
Two-layer Concrete
P
Mixture 1
h1
d
Mixture 2
h2
a0
CMOD
4
Material 1: 100% Plain, Material 2: 0% FRC
3.5
Material 1: 0% Plain, Material 2: 100% FRC
3
Load P (kN)
Material 1: 33% Plain, Material 2: 66% FRC
2.5
Material 1: 33% FRC Material 2: 66% Plain
2
1.5
1
0.5
0
0
0.5
1
CMOD (mm)
1.5
2
Recycled Concrete Aggregate
Recycled Concrete Aggregate
Advantages of RCA
Performance
 Improves strength of base when used in base layer
 Potential to minimize D-cracking and ASR
Economic
 Limited haul distance
 Reduced disposal costs
 Lower aggregate cost = lower concrete cost
 Overall project savings
Resource Conservation (RCAC is a green
material)
 Reduced land disposal and dumping
 Conservation of virgin aggregates
 Reduced impact to landscapes
G. P. Gonzalez, H. K. Moo-Young, “Transportation Applications Of Recycled Concrete Aggregate”, FHWA
State of the Practice National Review September 2004.
Recycled Concrete Aggregate
Some potential disadvantages
Reduced strength and modulus
 Particularly with a large amount of recycled fines
Higher drying shrinkage
 The reduced stiffness of aggregates reduces the
restraint to paste shrinkage
 Part of the RCA is just hydrated paste… this will
also shrink when dried
Recycled Concrete Aggregate
Can we mitigate the disadvantages?
Use low w/cm concrete (below ~0.35)
 Drying shrinkage will be greatly reduced due to
decrease in diffusivity
 Strength and stiffness will be satisfactory
But what about autogenous shrinkage in low
w/cm?
 There is evidence that RCA can be used as an
“internal curing agent” by saturating the aggregate
prior to use
Recycled Concrete Aggregate
Some findings from literature
When used with a very low w/cm, RCAC
compressive strength can exceed 9000psi at 28 d
Autogenous shrinkage can be lowered by 60% by
adding saturated RCA
While there are no reports in the literature, it is likely that RCA
increases tensile creep, which would reduce propensity for
shrinkage cracking or curling
I. Maruyama, R. Sato, “A trial of reducing autogenous shrinkage by recycled aggregate”, in Proceedings
of self-desiccation and its importance in concrete technology, Gaithersburg, MD, June 2005.
Experimental Pavement
Sections & Instrumentation
Opportunity to test new ideas!!
Factor Levels
16 instrumented slabs
FRC vs. Plain
Slab Size and Curling
80 ft
Joint Type - Dowel vs. no dowels
Base Type
75 ft
Gaging
RH and Temperature profile
Strain
Deflection
Joint opening
400 ft
DIA
Project
FULL-SCALE TESTING
(Advanced Transportation Loading ASsembly)
• 80,000 lbs max load
• 85 feet loading length
• 65 feet at 10mph
• Uni- or Bi-directional
• Variable lateral position
Test ideas at UIUC
Use of Manufactured Sand
Gradation
 Coarse graded
material
 High amount of
fines (passing
#200), exceeding
the 3% limit
recommended by
ASTM.