UHPC Overlays

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

7

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

8

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

12

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


14

ExistingSuperstructure

UHPC Overlay

Section View


15

Specially-Designed, Multi-Functional UHPC Placement Machine


16

Laporte Road Bridge Project

17Laporte Road Bridge, Brandon, Iowa


18

Existing Bridge Deck Distress…


19


20

Completed May 2016


21

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


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

27

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

40

Large-Scale Test Set-up LVDTs To Measure Slip


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


42

Failure Mode

How Do Small- and Large-Scale Tests Compare…

43

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

44

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


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


App

lied

Load

(kN

)

App

lied

Load

(kip

)





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


App

lied

Load

(kN

)

App

lied

Load

(kip

)





49

Key Finding: Failure Dependent on Relative Lug / Stud Locations

50

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


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


6.5d Rebar Dowelb

ExposedAggregate

5 in


53

Pu = 318 kips

Detail “A”

Detail “B”Detail “A”

Pu = 297 kipsCalculated Resistance (AASHTO) = 245 kip

Detail “A” vs. “B”


54


55

Strong Connection: 8 Dowel / Side

Strong vs. Weak Deck-Haunch Connection

20 in

W10x60

24 in


6.5d Rebar Dowelb

5 in

178 in

5 in

178 in

Weak Connection:4 Dowels / Side


56

Detail “A”

Weak – 4 Dowels / SideStrong – 8 Dowels / Side

429 kipsFailure LoadAASHTO Resistance

Strong vs. Weak Deck-Haunch Connection

318 kips229 kips245 kips


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


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


App

lied

Loa

d (k

N)

App

lied

Loa

d (k

ip)




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

Documents

UHPC Overlays