2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Sustainable Pavement Construction Utilizing Engineered Unbound
Aggregate Layers
Erol Tutumluer, Professor of Civil EngineeringPaul F. Kent Endowed Faculty [email protected] of Illinois at Urbana-Champaign
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012 2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Aggregates In High Demand• As the transportation infrastructure continues to age and
grow and the need for repairs, reconstruction and new construction grows, the demand for aggregates expands– The worldwide demand for construction aggregates is estimated to
be rising by 4.7 percent annually– In the US alone, nearly 1.9 billion metric tons were produced in
2009 at a value of approximately $17.2 billion (www.nssga.org)– Approximately 27% of the crushed stone and 23% of the total sand
and gravel produced annually in the US are used in pavement base construction
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Role of Aggregate Base
Aggregate
Fine-grained subgrade soil
Wheel
Asphalt Concrete
Load Distribution
In unpaved roads, thinly surfaced low to moderate volume roads and thicker airport pavements, Unbound Aggregate Layers serve as major structural components of the pavement system
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
OWNERSHIP BITUMINOUS
/FUNCTIONAL UNPAVED SURFACE OR RIGID TOTAL
SYSTEM TREATMENT SURFACE
Total Rural 1,369,503 178,826 1,459,896 3.008,225
Total Urban 50,521 71,192 940,949 1,062662
Total Rural and Urban 1,420,024 250,018 2,400,845 4,070,887
Road System in the US by Surface Type (miles)
Public Roads46,893 mi of Interstate Highway116,573 mi of other National Highway System roads3,907,420 mi of other roads
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Unbound Aggregate Layers Constructed by Transportation Agencies
96%
65%
24%
46%
(44)
(30)
(11)
(21)
0 10 20 30 40
0% 20% 40% 60% 80% 100%
Base course
Subbase course
Open graded drainagelayer
Pavement workingplatforms for subgrade
stability applications
Number of Responses
Percentage of Survey Respondents
46 survey respondents
Unbound Aggregate Pavement Base / Subbase Applications (46 respondents –NCHRP Synthesis 43-03 -2012)
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Sustainable Practices Target• Better characterizing and utilizing unbound aggregate
layers by incorporating recent advances in materials characterization– Stress-dependent modulus behavior– Directional dependency (anisotropy) of layer stiffness– Moving wheel load effects
University of Illinois – FastCell
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Resilient Modulus (MR) Distributions in the Base
Dep
th (i
n.)
0 20 40 60 80 100
4
10
15
20
25
30
Radial distance (in.)
AC Modulus = 400 ksi0
Subgrade
- Nonlinear
10000 psi 15000 20000 25000 28000
Subgrade MR = 6 ksi
10000
10000
10000
15000
1500020000
2800025000
MR 2318 0.64d
0.065
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Anisotropic Moduli from UI-FastCell Testing
High Quality Aggregate Base
Tutumluer and Seyhan (1999) TRB Record No. 1687
Vertical Modulus
Horizontal Modulus
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Sustainable Practices Target• Limiting the thicknesses of energy-intensive bound layers
– availability and cost of asphalt & Portland cement– high CO2 emissions
• Using of aggregates as a lower cost, green alternative (CO2 emissions – 4 for aggregates: 50 for HMA /ton AC)
• Using the highest quality materials in thinner layers
• Using local aggregates to reduce:– noise and air pollution– human disturbance– transport costs and transport energy requirements
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Best Value Granular Material for Road Foundations
Minnesota DOT Research Project, 2008 - 2011
18.81
21.76
14.66 14.47
7.77 6.82
0
5
10
15
20
25
Base Subbase
Equi
vale
nt M
R(k
si)
High QualityMedium QualityLow Quality
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
MnDOT Project Research ObjectiveDemonstrate that locally available materials can be economically efficient in the implementation of the available mechanistic based design procedures in Minnesota through
MnPAVE Mechanistic-Empirical Pavement Design Method
Benefits(i) proper material selection & utilization (ii) aggregate layer thickness optimizations during
the design process based on mechanistic material properties related to performance
(iii) more economical use of the locally available aggregate materials in Minnesota
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
MR & Strength Values Linked to Quality
21.22 21.73
16.73 14.48
9.397.08
0
5
10
15
20
25
Base Subbase
Equi
vale
nt M
R(k
si)
6-in. AC
High QualityMedium QualityLow Quality
18.8121.76
14.66 14.47
7.77 6.82
05
10152025
Base Subbase
Equi
vale
nt M
R(k
si)
8-in. AC
High QualityMedium QualityLow Quality
29.65
22.6222.85
15.8113.18
8.28
05
101520253035
Base Subbase
Equi
vale
nt M
R(k
si)
4-in. AC
High QualityMedium QualityLow Quality
(Average MR)Unit: ksi
In some cases, the granular subbase moduli were higher!!!
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
MnPAVE Sensitivity Analysis MatrixCL
Wheel load = 9 kipType pressure = 80 psi
PG 58-34
High, Medium & Low QualityUnstabilizedAggregate Base
High, Medium & Low QualityAggregate Subbase
AsphaltConcrete
Base
Subbase
Subgrade - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Engineered Soil
Undisturbed Soil
3”- 6” - 9” -12”
6”- 12” - 18”
12” - 36”
(AC)4”- 6”- 8”
1 in. = 25.4 mm
Beltrami&
Olmsted
E = 2, 4, 7, 10 ksi
50% * E
20-year ESALs = 0.2, 0.6, 1.5, 3, 6 Million
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Effect of Aggregate Material Quality
Subbase material quality significantly impacts rutting performance
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
5 10 15 20 25 30 35 40 45 50Pavement Service Life (Years)
H-H - Rutting
H-L - Rutting
L-H - Rutting
L-L - Rutting
L-HH-L
TRB Paper 11-3462 by Xiao, Tutumluer and Siekmeier
Base-Subbase
Base-SubbaseBase-SubbaseBase-Subbase
RuttingPerformance
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Aggregate Quality Is Important!
Courtesy Texas DOT
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
UIUC Aggregate Image Analyzer
0 100 200 300 400 500Angularity Index
Fric
tion
Ang
le (o
)4041424344454647
Crushed 436
Gravel 200
50/50 Blend322
Shear Strength Properties From Rapid Shear Triaxial Tests
Aggregate Shape, Texture & Angularity
Rao, Tutumluer and Kim (TRB 2002)
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Effects of Angularity & Surface Texture on MR
Pan, Tutumluer and Anochie Boateng (2006) TRB Record No. 1952
y = 152281e0.001x
R2 = 0.86
175000
200000
225000
250000
275000
200 300 400 500 600Composite AI Index
Res
ilien
t Mod
ulus
MR (
kPa)
Crushed granite-uncrushed gravel blendsCrushed limestone-uncrushed gravel blendsCrushed gravel-uncrushed gravel blendsSlag-uncrushed gravel blendsSandstone-uncrushed gravel blendsUncrushed gravel only
y = 166430e0.1848x
R2 = 0.91
175000
200000
225000
250000
275000
0.50 1.00 1.50 2.00 2.50 3.00
Res
ilien
t Mod
ulus
MR
(kPa
)
Composite ST Index
Crushed granite-uncrushed gravel blendsCrushed limestone-uncrushed gravel blendsCrushed gravel-uncrushed gravel blendsSlag-uncrushed gravel blendsSandstone-uncrushed gravel blendsUncrushed gravel only
• No fines, dry, and same gradation • All the specimens tested at the same voids content of 41%
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Need for Sustainable Practices in Illinois• Illinois Subgrade Stability Manual and Illinois DOT (IDOT)
pavement design procedures do not differentiate between aggregate properties when recommending layer thickness
• IDOT Experimental Feature IL 03-01 indicated aggregate properties have a significant effect on their performance in subgrade replacement and subbase applications– 203-mm crushed aggregate layer performed as well as 305-mm. of
the same material– 203-mm crushed aggregate performed better than a 305-mm gravel
More economical (SUSTAINABLE) use of aggregates by either Reducing Layer Thickness
or Avoiding Aggregate Failures
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
ICT R27-1 Research Project Performances of crushed gravel, dolomite, & limestone aggregates studied in Illinois Engineered properties & studied behavior
% fines, plasticity of fines, aggregate shape/angularity, & moisture state
2006-2009
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
ICT R27-1 Lab Test Matrix• Aggregate type: (1) dolomite, (2) limestone, (3) gravel
• Particle shape & angularity quantified via imaging
• Fines content: 4%, 8%, 12%, & 16% passing sieve No.200
• Plasticity of fines: 0% (non-plastic mineral filler) & ~10%
• Moisture-density (compaction) condition: At optimum moisture content (OMC), 90% of OMC, and 110% of OMC (Standard Proctor Procedure, AASHTO T99)
4x2x3 factorial studied for each aggregate material
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
(3) gravel
(1) dolomite
(2) limestone
typical midrange IDOT CA-6 gradations
4%, 8%, 12%, & 16% fines
Engineered Gradations
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
ICT R27-1 Project Findings• The most important parameter at low fines contents was
found to be the aggregate type/angularity (crushed vsuncrushed)– Crushed aggregates showed higher tolerance to accommodate
increasing %fines (16-17% for crushed vs 12-14% fines for gravel)
• The second most important parameter to affect aggregate behavior was plasticity of fines
• High amounts of plastic fines at wet of optimum moisture conditions created the worst combination and destroyed the load transfer matrix, resulting in excessive permanent deformations
ICT R27-1 Study –Tutumluer, Mishra and Butt (2009)
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
y = 7.8302x0.5477R² = 0.9882
y = 12.61x0.5222R² = 0.9755
0
50
100
150
200
250
300
350
400
450
0 100 200 300 400 500 600 700 800
Axial R
esilien
t Mod
ulus (M
pa)
Bulk Stress (KPa)
Comparing Limestone and Gravel at 4% Fines, Wopt
G_0_NP_OptL_0_NP_Opt
Crushed Limestone Shows Consistently Higher MR values compared to Uncrushed Gravel
Effects of Crushed vs Uncrushed on MR
Mishra & Tutumluer (GeoShanghai 2010)
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
y = 4.2282x0.6477R² = 0.9835
y = 3.2801x0.6532R² = 0.9707
0
50
100
150
200
250
300
350
0 100 200 300 400 500 600 700 800
Axial R
esilien
t Mod
ulus (M
pa)
Bulk Stress (kPa)
Effect of % Fines on MR of Gravel with Non‐Plastic Fines
Higher fines results in lower MR and lower rate of stress hardening
16 % Fines 90% Wopt
4 % Fines 90% Wopt
Effects of Percent Fines on MR
Mishra & Tutumluer (GeoShanghai 2010)
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
More Drastic Effect on Permanent Deformation than Resilient Modulus
Comparing Dolomite specimens with 4% and 16% Nonplastic Fines Tested at Std Proctor Optimum Moisture Content
ICT R27-1 Study –Tutumluer, Mishra and Butt (2009)
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
0 100 200 300 400 500 600 700 800 900 1000
Perm
anen
t Def
orm
atio
n (m
m)
Number of Cycles
4% Fines8% Fines12% Fines16% Fines
Dolomite with NP fines at Wopt
D – 8% NPD – 4% NP
D – 12% NP
D – 16% NP
% Fines on Permanent Deformation p
ICT R27-1 Study –Tutumluer, Mishra and Butt (2009)
Stabilizing effects
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
0
0.1
0.2
0.3
0.4
0.5
0.6
0 100 200 300 400 500 600 700 800 900 1000
Perm
anen
t Def
orm
atio
n (m
m)
Number of Cycles
Gravel with NP fines at 90% Wopt
G – 4% NP
G – 8% NPG – 12% NP
G – 16% NP
% Fines on Permanent Deformation p
ICT R27-1 Study –Tutumluer, Mishra and Butt (2009)
No stabilizing effects
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
0
0.1
0.2
0.3
0.4
0.5
0.6
0 100 200 300 400 500 600 700 800 900 1000
Perm
anen
t Def
orm
atio
n (m
m)
Number of Cycles
Dolomite Non-Plastic 90% Wopt
Dolomite Non-Plastic 110% Wopt
Dolomite Plastic 90% Wopt
16% Fines Content
Plastic Fines are Bad Even at Low Moisture Contents
D – NP 90% wopt
D – NP 110% wopt
D – Plas 90% wopt
Effect of Plasticity of Fines on p
ICT R27-1 Study –Tutumluer, Mishra and Butt (2009)
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
0
0.5
1
1.5
2
2.5
3
0 100 200 300 400 500 600 700 800 900 1000
Perm
anen
t Def
orm
atio
n (m
m)
Number of Cycles
Gravel 12% Non-Plastic FinesDolomite 12% Non-Plastic FinesGravel 12% Plastic Fines
Effect of Plastic Fines on p - 110% Wopt
Plastic Fines with wet conditions create the worst problems
G – 12% Plastic
G – 12% NPD – 12% NP
ICT R27-1 Study –Tutumluer, Mishra and Butt (2009)
Shear Failure!!!
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Aggregate Layer Design ConceptsRutting due to
base compaction
AggregateSoil
Rutting due to shear in base
AggregateSoil
b
b/3
b
b/3
• Resist shear deformation within the aggregate base– Crushed, angular stone for higher stability/strength
– Proper compaction!!!
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
ICT R27-81 Research Project
Construct Engineered Aggregate Test Sections over Soft Subgrade
Evaluate Performance through Accelerated Testing Field Characterization
DCP, LWD, GeoGauge, Nuclear, and Handheld GPR
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
ATREL Full-Scale Test Sections
University of Illinois, ATREL Facility
Cell 3 Cell 4
Cell 2 Cell 5
Cell 1 Cell 6
Basin Flow Direction towards West
In total, 6 cells constructed in 3 test strips, 237.5 ft each
The test strips separated by 12 ft
Test Cells Constructed for APT Testing
Each Cell Had 3 Test Sections
122.5’ 22.5’10’10’ 15’ 15’ 15’
T T2 310’ 10’
130ft ATLASCrawlerPlacement
TransitionZoneTestSectionSpeedStabilizationZone
14” 14” 12” 8” 8”8” 12” UnboundAggregateLayer
CBR = 3 Subgrade top 12” (305 mm) tilled & compacted
18ft
Transversedrainsinstalled Test cell 5 had a subgrade of CBR 6 with aggregate layers of thicknesses 254 mm, 203 mm, and 152 mm respectively
Topview
Profileview
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Subgrade Soil Characteristics
Soil is CL-ML
OMC = 10.2%MDD = 19.9 kN/m3 (126.6 pcf)
Standard Compactive Effort
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Tilling Stage-I to mix soil from top 305 mm
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Moisture Content Determination with Microwave
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Adding Water to Achieve Target CBR
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
DCP Testing – CBR Profile
LOG (CBR) = 0.84 – 1.26 * LOG (PR)
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Light Weight Deflectometer (LWD), GeoGauge, & Electrical Density Gauge (EDG) on Finished Subgrade
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Asphalt Prime Coating for Moisture Retention
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Subgrade Pressure Cell Installation along Wheel Path
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Aluminum Paint & Foil at Subgrade Interface
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Aggregate Placement & Compaction
Aggregate Bases Constructed
Cell Number Subgrade CBR Material Type Aggregate Layer Thickness (in.)
1 3 Uncrushed, HighFines, Non-Plastic 8, 12, 14
2 3Crushed, Low Fines, Moderately Plastic
8, 12, 14
3 3 Crushed, High Fines, Non-Plastic 8, 12, 14
4 3 Crushed, High Fines, Non-Plastic 8, 12, 14
5 6Crushed, Low Fines, Moderately Plastic
6, 8, 10
6 1 Large Aggregate topped with CA-6
12-in. thick large aggregate overlain
by 6-in. CA-6
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Accelerated Testing & Loading System - ATLAS
10 kip (44 kN), Single Wheel Load - 110 psi (759 kPa)
Tire Pressure
22.5’ 22.5’Wheel Span = 85 feet
(constant Speed Achieved for 65 feet)
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Rut Measurement at Different Passes
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Investigation of Failure Modes by Trenching
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Cell 1 Uncrushed Gravel Test Sections
Section1(14”‐356mm)
Section2(12”–305mm)
Section3(8”203mm)
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Measured Subgrade Stress Levels (Cell 1: N = 2)
3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 8020406080100120140160180200
Time(sec)
SubgradeStre
ss(kPa)
305mmAggregateLayer203mmAggregateLayer169.8kPa(24.6psi) 195.5kPa(28.4psi)
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Excavated Trench Photos Showing Surface and Aggregate-Subgrade Interface Deformations
356-mm (14-in.) thick aggregate layer
Subgrade displacement laterally offset from wheel path
Gravel undergoing shear failure
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 201254
Cell 1 Subgrade – LWD, GeoGauge & DCP
Section3subgradewassignificantlystrongerthantheothertwosections
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Cell 1: Uncrushed Gravel Layer Moduli
GeoGuagemeasuredmodulishowsimilartrendasinsubgrade
LWDresultssignificantlyaffectedbysubgradeduetogreaterdepthofinfluence
Notethehighercompactionlevelsachievedonstrongersubgrade
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Laboratory Assessment of Aggregate Behavior
ϕ=150mm;H=150mm
1000loadapplications
s =104kPa (15psi)
d =104kPa (15psi)
1d
s
s s
Uncrushed gravel underwent significantly higher permanent deformation
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Custom Designed GPR Track for Rut- Measurement
Ground Penetrating Radar (GPR) Measurements Aggregate vs. Subgrade Rutting
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Cell 4 - Limestone - 168 passes
Section 1 (14” 356 mm)
Section 2 (12” 305 mm)
Section 3 (8” 203 mm)
Rutting primarily in subgrade (wheel path directly corresponds to subgrade dip)
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
‐40 ‐30 ‐20 ‐10 0 10 20 30 40
‐40
‐20
0
20
40
60
80
100
120
LateralPosition(in.)N<<‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐>>S
RutDepth(mm)
Section1@N=1
Section1@N=10
Section1@N=55
Section1@N=100
Section1@N=168
Cell 4 – Limestone (356 mm) – Rut Development Due to Subgrade
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
‐40 ‐30 ‐20 ‐10 0 10 20 30 40
‐80
‐60
‐40
‐20
0
20
40
60
80
100
120
LateralPosition(in.)N<<‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐>>S
RutDepth(mm)
Section1@N=1
Section1@N=10
Section1@N=47
‐40 ‐30 ‐20 ‐10 0 10 20 30 40
‐40
‐20
0
20
40
60
80
100
120
LateralPosition(in.)N<<‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐>>S
RutDepth(mm)
Section1@N=1
Section1@N=10
Section1@N=55
Section1@N=100
Section1@N=168
Uncrushed Gravel
Crushed Limestone
Early and Sudden Shear Failure in the Gravel Layer
Progressive Failure of the Subgrade
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Cell 3 – Dolomite Section 1 (356 mm)
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Cell 3 – Dolomite Section 2 (305 mm)
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Cell 3 – Dolomite Section 3 (203 mm)
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Cell 6 - Large Sized AggregateConstructed on CBR =1 Subgrade
Mishra and Tutumluer (2nd ICTG, Hokkaido 2012)
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012 2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
-48 -40 -20 0 20 40 48
100
80
60
40
20
0
-20
-40
-48 -40 -20 0 20 40 48
100806040200
-20-40-60
Rut
Dep
th (m
m)
Lateral Position (in.)
1 Pass 10 Passes 33 Passes 63 Passes
Rut
Dep
th (m
m)
Lateral Position (in.)
1 Pass 10 Passes 33 Passes 63 Passes 100 Passes 159 Passes
Section 2Manteno (3-5 in. size)
North Wheel Path(without Geotextile)
South Wheel Path(with Geotextile)
Effect of Woven Geotextile
Mishra and Tutumluer (2nd ICTG, Hokkaido 2012)
New ICT R27-124 Research Project(8/2012 – 7/2014) Evaluation of “Aggregate Subgrade” Materials Used as Pavement Subgrade/Granular Subbase “Aggregate Subgrade” materials – Large-sized virgin aggregates,
recycled concrete aggregate (RCA), reclaimed asphalt pavement (RAP), or combinations
Develop characterization techniques Evaluate field performances through accelerated full-scale testing
Unsurfaced working platform application Asphalt surfaced low volume pavements
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Mechanisms contributing to failure of unsurfaced pavements change significantly based on aggregate quality
Uncrushed gravel with high fines underwent internal shear failure
Pavement sections with crushed aggregates failed primarily due to shear movement of the subgrade
Effect of compactive effort was critical to layer stability when crushed aggregates lad low (< 5%) fines content
ICT R27-124: Lessons Learned
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Benefits to Illinois DOT• Anecdotal evidence based on years of experience with
the different types of aggregate available throughout the state suggests that IDOT uses approximately 1.7 million metric tons of aggregate in improved subgrade applications annually
• With an average cost per metric ton of $14, IDOT spends approximately twenty-nine million dollars per year for aggregate improved subgrades
More economical (SUSTAINABLE) use of aggregates by either Reducing Layer Thickness
or Avoiding Aggregate Failures
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
• replacing conventional aggregates with more marginal natural materials where possible
• replacing conventional aggregates with waste / by-product / residue / recycled materials (RAP, RCA, etc.)
Sustainable Practices Target
67.4% 80.4%
21.7%4.3%
Reclaimed AsphaltPavement (RAP)
Recycled ConcreteAggregates (RCA)
Other (BlastFurnace Slag, GlassCullet, etc.)
None of these
Unbound Aggregate Pavement Base /Subbase Applications (46 respondents –NCHRP Synthesis 43-03 -2012)
http://ict.illinois.edu
ICT R27-27 Research Project
TRB 2010 Paper by Deniz, Tutumluer & Popovics 2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Target Sustainable Aggregate Production
• Research that leads to advances in aggregate technology and innovative products and applications needed to target specific transportation projects
– matching future regional needs with availability of resources – conservation of water and energy in aggregate production and
applications – making beneficial use of micro-fine material – a byproduct
of quarry operations
New ICT R27-125 Research Project(8/2012 – 7/2014) Sustainable Aggregates Production -- Green Applications for Aggregate By-products Investigate and develop a method(s) to utilize product fractions currently
being wasted (approximately 8% of mined & less than ¼ in.) to lower overall costs to IDOT and extend the use of natural aggregate resources
Modify existing specifications or Develop new specifications/mixes to utilize “higher fines materials” PHASE I: STUDY OF ILLINOIS AGGREGATE BY-PRODUCTS PHASE II: GREEN APPLICATIONS FOR AGGREGATE BY-PRODUCTS
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Sustainable Practices Also Target• Adapting and utilizing best practices of road
construction in European and other foreign countries, i.e. South Africa, Australia, etc.
Example: South African Inverted Pavements
High Quality Well Graded Crushed Stone (G1)
• Plasticity Index zero toslightly plastic
• Compacted utilizing a finalslushing process to adensity specification of 86to 88% of “solid density”(~ 100 to 105% ModifiedProctor – AASHTO T180)
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Subgrade
Cement Treated Subbase (3-5% cement)
High Quality Crushed Aggregate Base
Asphalt Concrete3-5 cm
15 cm
FHWA Report FHWA-PL-03-001http://international.fhwa.dot.gov/paveprestech/techdoc.htm
15-20 cm
South African StrategyInverted Pavement Design
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
• Need to do more with less $ while maintaining performance
• Inverted Pavement Systems are green and sustainable Make optimum use of the compressive
characteristics unbound aggregates Better compaction of aggregate placed over
stabilized Less cracking & improved fatigue life due to
lower tensile stresses at bottom of asphalt layer Minimize reflective cracking potential of lightly
(3-5%) cement stabilized subbase Protect subgrade from wheel load stresses Result: Improved Pavement Performance
Why Inverted Pavements?
2nd Int. Conf. on Transportation Geotechnics, Sapporo, Hokkaido, Japan – Sept. 10-12, 2012
Thank you!..