uhpc overlays
TRANSCRIPT
UHPC Overlays:An Emerging Repair Solution
Zach Haber, PhDBridge Engineering ResearcherGenex Systems – FHWA TFHRC
Ph: 202-493-3469Email: [email protected]
Bridge Deck Deterioration
2
Traditional Solutions
3
• High-Performance Concretes (HPC)• Low-Slump Concretes• Latex-Modified Concrete (LMC)• Asphalt with Water-Proofing Membrane• Polymer-Based Materials
Potential Advantages of UHPC Overlays
4
• Very Low Permeability • Very Good Freeze-Thaw Resistance• Good Abrasion Resistance• Low Shrinkage, Very Small Crack Width• Bonds Well to Existing Concrete• High Strength and Stiffness
Comparison of Overlay Thickness
5
Overlay Type Overlay Thickness, inHigh-Performance Concrete 1 – 5*
Low Slump Concrete 1.5 – 4*Latex-Modified Concrete 1 – 5*
Asphalt with a Membrane 1.5 – 4*Polymer-Based 0.13 – 6*
UHPC 1 - 2
*Data from NCHRP 20-07 by Krauss et al. 2009
Properties of UHPC Overlay:
6
In general, the properties of UHPC
formulated for an overlay are similar
to those found in typical UHPC
formulations
There are some exceptions!
Properties of UHPC Overlays: Tensile Behavior
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0
2
4
6
8
10
12
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
0 0.005 0.01
Aver
age
Axia
l Str
ess
(MPa
)
Aver
age
Axia
l Str
ess
(ksi
)
Average Axial Strain
NOTE: Both formulations had 3% fiber reinforced by volume, and had compressive strengths between 13 ksi - 15.5 ksi
Direct Tension Test Method
Properties of UHPC Overlays: Bond to Concrete
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0.413 ksi0.356 ksi
0
1
2
3
4
5
6
0.0
0.2
0.4
0.6
0.8
1.0
Inte
rfac
e Te
nsile
Bon
d St
reng
th (M
Pa)
Inte
rfac
e Te
nsile
Bon
d St
reng
th (k
si)
Direct Tenion Pull-Off Test(ASTM C1583)
Typical Formulation
*Concrete had an exposed aggregate (EA) surface preparation
Properties of UHPC Overlays: Shrinkage
9
-800
-600
-400
-200
0
0 20 40 60 80 100 120 140 160 180 200
Shrin
kage
(µε)
Time (days)
Drying Shrinkage
Typical
Measured Using ASTM C157
-800
-600
-400
-200
0
0 20 40 60 80 100 120 140 160 180 200
Shrin
kage
(µε)
Time (days)
Autogenous Shrinkage
Typical
Properties of UHPC Overlay: Rheology
10
Typical UHPCFormulation
Overlay UHPCFormulation
Properties of UHPC Overlay: Rheology
11
Typical UHPCFormulation
Overlay UHPCFormulation
Non-Thixotropic Thixotropic
Deployments
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Chillon Viaduct, Switzerland
Laporte Road Bridge, Brandon, IA
We will look at two previous deployments of UHPC as a bridge deck overlay:
Chillon Viaduct UHPC Overlay Project
13Chillon Viaduct near Lausanne, Switzerland
Chillon Viaduct UHPC Overlay Project
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ExistingSuperstructure
UHPC Overlay
Section View
Chillon Viaduct UHPC Overlay Project
15
Specially-Designed, Multi-Functional UHPC Placement Machine
Chillon Viaduct UHPC Overlay Project
16
Laporte Road Bridge Project
17Laporte Road Bridge, Brandon, Iowa
Laporte Road Bridge Project
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Existing Bridge Deck Distress…
Laporte Road Bridge Project
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Laporte Road Bridge Project
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Completed May 2016
Laporte Road Bridge Project
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Overlay Bond Testing• 5 Locations Tested
UHPC-ConcreteInterface
Pre-existing damage inthe concrete deck
Load
InterfaceSaw Cut
1.5" (38 mm)
1" (25 mm)
OverlayMaterial
Good Apparent Bond
Cores From Test Location with:Poor Apparent Bond
Laporte Road Bridge Project
22
UHPC-concrete interface Pre-existing delamination in deck concrete
UHPC overlay
Existing deck concrete
Concrete Deck
UHPC OverlayInterface
Scanning Electron Microscope Imaging
Visual Inspection of Test Locations
Concluding Remarks
23
• UHPC can be formulated specifically for overlay applications.
• There are a number of potential advantages to UHPC overlay
• Previous deployments have been successful
• Future deployments planned by New Mexico, Delaware, & Iowa
PDH Questions
24
Which of the following is the primary difference between a typical UHPC formulation and one designed for overlays
a) Compressive Strengthb) Rheologyc) Bond Strength to Concrete d) Tensile Ductility
PDH Questions
25
Select all that apply:
Which of the following are advantages of UHPC overlays?
a) Very low permeability b) Very good freeze-thaw resistancec) Will completely replace conventional solutionsd) Good bond to concretee) Good abrasion resistance
UHPC Haunch Connections:Status Update
Zach Haber, PhDBridge Engineering ResearcherGenex Systems – FHWA TFHRC
Ph: 202-493-3469Email: [email protected]
Background
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Hidden Deck-to-Girder Connections in NY State:
Background
28
Hidden Deck-to-Girder Connections in NY State:
Short Studs Long Studs
Background
29
In Summary, These Connections are…• Structurally Effective for Fatigue and
Ultimate Limit States
Yet…
• Can Have Constructability Challenges • Precast Decks Have a Tendency to Crack
Due to Haunch Void
Alternative Design Concepts
30
• UHPC Shear Lug Connection
A
A
B B
B-B
A-A
Precast Concrete Deck
Steel Girder
Shear Studs
UHPC Shear Lug
Field-Cast UHPC
Shear Studs
Alternative Design Concepts
31
• Rebar Dowel Shear Connectors
A-ADetail A
Precast Concrete Deck
Rebar Connectors
ExposedAggregate
Field-CastUHPC
A
A
Steel Girder
Shear Studs
Rebar Connectors
Field-Cast UHPC
Questions to be Addressed:
34
UHPC Shear Lug Connections• What is the Direct Shear Strength of UHPC?
• Interaction Between UHPC Lug and Shear Studs?
• Characteristic Failure Modes, Compare w/ AASHTO?
Rebar Dowel Connections • Interaction Between UHPC Haunch and Rebar
Connectors
• Characteristic Failure Modes, Compare w/ AASHTO?
Direct Shear Strength – Small-Scale Testing
36
UHPC Prism Specimen
2” 2”
6”
Goal: Establish some baseline data for direct shear strength of UHPC
Direct Shear Test Set-Up
0 50 100 150 200
0
50
100
150
200
250
300
350
0123456789
0 5 10 15 20 25 30
Compressive Strength of UHPC, f 'c (MPa)
Shea
r St
ress
, τ (M
Pa)
Shea
r St
ress
, τ (k
si)
Compressive Strength of UHPC, f 'c (ksi)
Preliminary Testing: Small-Scale Testing
37
Graybeal (2012) – Shear Stress Demand on Minimum Shear Plane
Crane (2010) – Direct Shear Failure of Uncracked UHPC
Specimen DetailsPreliminary Testing: Large-Scale Testing
38
UnbondedSurface
UHPC
UHPC Shear Lug
Conventional Concrete Deck Donut
8.5”
Specimen DetailsPreliminary Testing: Large-Scale Testing
39
Prior to Casting UHPC UHPC Lug Geometry
6” & 8”
6”
Preliminary Testing: Large-Scale Testing
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Large-Scale Test Set-up LVDTs To Measure Slip
Preliminary Testing: Large-Scale Testing
41
0 0.5 1 1.5 2 2.5
0
500
1000
1500
2000
2500
3000
0
100
200
300
400
500
600
700
0 0.02 0.04 0.06 0.08 0.1
Haunch Slip (mm)
App
lied
Load
(kN
)
App
lied
Load
(kip
)
Haunch Slip (in)
6” x 6” Lug
6” x 8” Lug
A
B
Load Direction
Geometry: “A” x “B”
Lug Geometry
Preliminary Testing: Large-Scale Testing
42
Failure Mode
How Do Small- and Large-Scale Tests Compare…
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0 50 100 150 200
0
50
100
150
200
250
300
350
0123456789
0 5 10 15 20 25 30
Compressive Strength of UHPC, f 'c (MPa)
Shea
r St
ress
, τ (M
Pa)
Shea
r St
ress
, τ (k
si)
Compressive Strength of UHPC, f 'c (ksi)
6”x6” Lug
6”x8” Lug
Large-ScaleSmall-Scale (2”x2” Lug)
Phase II Testing: Deck-to-Girder Connections
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Concrete Deck Segment Steel Beam Section
UHPC Haunch
Phase II Testing: Deck-to-Girder Connections
45
Objectives
• Investigate UHPC Haunch Behavior
• Investigate Influence of Detailing
• Characterize Failure Modes
• Compare with AASHTO LRFD
UHPC Lug Connections
46
20 in
W10x60
24 in712 in
712 in
6 in
6 in
712 in
78" Dia. Nelson Stud
UHPC
2 Studs / Side 4 Studs / Side 6 Studs / Side
Line of Symmetry3 in
8 in
78" Dia. Nelson Stud
212 in
Precast ConcreteDeck DonutUHPC
6”x6” Lug with Different Stud Configurations
0 0.5 1 1.5 2 2.5
0
500
1000
1500
2000
050
100150200250300350400450500
0 0.2 0.4 0.6 0.8 1
Average Haunch Slip (mm)
App
lied
Load
(kN
)
App
lied
Load
(kip
)
Average Haunch Slip (in)
Capacity of 6"x6" UHPC Lug - Preliminary Testing
AASHTO Factored Resistance
Results: 2 Studs / Side
47
0 0.5 1 1.5 2 2.5
0
500
1000
1500
2000
050
100150200250300350400450500
0 0.2 0.4 0.6 0.8 1
Average Haunch Slip (mm)
App
lied
Load
(kN
)
App
lied
Load
(kip
)
Average Haunch Slip (in)
Capacity of 6"x6" UHPC Lug - Preliminary Testing
AASHTO Factored Resistance
Results: 4 Studs / Side
48
0 0.5 1 1.5 2 2.5
0
500
1000
1500
2000
050
100150200250300350400450500
0 0.2 0.4 0.6 0.8 1
Average Haunch Slip (mm)
App
lied
Load
(kN
)
App
lied
Load
(kip
)
Average Haunch Slip (in)
Capacity of 6"x6" UHPC Lug - Preliminary Testing
AASHTO Factored Resistance
Results: 6 Studs / Side
49
Key Finding: Failure Dependent on Relative Lug / Stud Locations
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Centerline
LoadCase 1: 4 Studs / Side
Key Finding: Failure Dependent on Relative Lug / Stud Locations
51
Centerline
LoadCase 2: 6 Studs / Side
Rebar Dowel Connections
52
Stud & Dowel Locations
Detail “A”
312 in
ExposedAggregate;1.5" Recess
Line of Symmetry
20 in
W10x60
24 in
78" Dia. Nelson Stud
6.5d Rebar Dowelb
5 in
178 in
Detail “B”
Detail “A” vs. “B”
Line of Symmetry
8 in
2.5" x 78" Dia.Nelson Stud
Precast ConcreteDeck DonutUHPC
6.5d Rebar Dowelb
ExposedAggregate
5 in
Rebar Dowel Connections
53
Pu = 318 kips
Detail “A”
Detail “B”Detail “A”
Pu = 297 kipsCalculated Resistance (AASHTO) = 245 kip
Detail “A” vs. “B”
Rebar Dowel Connections
54
Rebar Dowel Connections
55
Strong Connection: 8 Dowel / Side
Strong vs. Weak Deck-Haunch Connection
20 in
W10x60
24 in
78" Dia. Nelson Stud
6.5d Rebar Dowelb
5 in
178 in
5 in
178 in
Weak Connection:4 Dowels / Side
Rebar Dowel Connections
56
Detail “A”
Weak – 4 Dowels / SideStrong – 8 Dowels / Side
429 kipsFailure LoadAASHTO Resistance
Strong vs. Weak Deck-Haunch Connection
318 kips229 kips245 kips
Rebar Dowel Connections
57
Stud & Dowel Locations
Effect of Dowel Length
5 in
178 in
8 in
312 in
4d Rebar DowelbLine of Symmetry
Line of Symmetry
8 in
2.5" x 78" Dia.Nelson Stud
Precast ConcreteDeck DonutUHPC
6.5d Rebar Dowelb
ExposedAggregate
5 in
Long – 6.5db
Short – 4db
0 10 20
0
500
1000
1500
2000
2500
3000
050
100150200250300350400450500
0 0.25 0.5 0.75 1
Average Haunch Slip (mm)
App
lied
Loa
d (k
N)
App
lied
Loa
d (k
ip)
Average Haunch Slip (in)
AASHTO Factored Resistance
Rebar Dowel Connections
58
6.5db
UH
PC H
aunc
h
Effect of Dowel Length
4db
Con
cret
e D
eck
Concluding Remarks
59
• These new connection details show promise
• Discovered that some additional detailing may be required
• Unanswered Question: Fatigue Resistance?
PDH Questions
60
TRUE or FALSE ?
The ultimate capacity of proposed deck-to-girder connection details always exceeded the factored resistance determined using AASHTO?
PDH Questions
61
Which of the following were found to influence the capacity of proposed deck-to-girder connection details?
a) Location of studs relative to the location of shear connectors.
b) Embedment length of shear connectors c) Geometry of the UHPC shear lugd) All of the above