behavior and strength of ultra-high performance concrete

Behavior and Strength of Ultra-High Performance Concrete in Shear

Paolo CalviDanielle Voytko

ABC-UTC Research SeminarJuly 30th, 2021

Project Contextualization2

(a) UHPC Bridge Girder

v

(b) UHPC Panel in biaxial stress

conditions

v

(c) UW Panel Element Tester(a) RC bridge girder (b) RC Panel in biaxial stress conditions

(c) Panel Element Tester


𝑉𝑛 = 𝑉𝑐 + 𝑉𝑠 + 𝑉𝑝

Overview

> Introduction

> Previous Work

> Research Motivation

> Experimental Program

> Experimental Results

> Comparison of Results

> Conclusions

> Recommendations for Future Work

> Acknowledgements

6

Overview

> Introduction

> Previous Work





> Conclusions


> Acknowledgements

7

Introduction

> University of Oklahoma (OU)

– UHPC mix design

– Material tests

> University of Washington (UW)

– Pure shear tests

– Material tests

> Florida International University (FIU)

– Material tests

> Iowa State University

– Material tests

> University of Nevada-Reno

– Performance of joints between panels

Collaboration

8

Introduction

> University of Oklahoma (OU)

– UHPC mix design

– Material tests

> University of Washington (UW)

– Pure shear tests

– Material tests

> Florida International University (FIU)

– Material tests

> Iowa State University

– Material tests

> University of Nevada-Reno

– Performance of joints between panels

Collaboration

9

Introduction

> Cementitious material

– Cement

– Slag

– Silica fume

– Ground quartz

– Flay ash

> Aggregate

– Fine sand

> Water

– Water-to-cement ratio: 0.17 to 0.25

> Fiber reinforcement

– Typically steel

– Standard 2% by volume

– Length: 6 to 60 mm

– Aspect ratio (L/D): 20 to 100

> Admixtures

– High range water reducer

– Retarder

Ultra-High Performance Concrete (UHPC) Composition

10

Introduction

Steel Fibers

Spajic Machines- Steel Fibers

11

Introduction

Steel Fibers

Spajic Machines- Steel Fibers

12

13 mm long0.2 mm diameter

Introduction

UHPC

www-personal.umich.edu/~eltawil/uhpc

13

Introduction

UHPC Properties

14

UHPC and Conventional Concrete Comparison

MaterialCompressive

Strength (psi)

Flexural

Strength (psi)

Tensile

Strength (psi)

Conventional Concrete 3,000-6,000 400-700 300-700

UHPC18,000-35,000

(up to 50,000)2200-3600 900-1500

MPa = psi/145

Overview

> Introduction

> Previous Work





> Conclusions


> Acknowledgements

15

Previous Work

> Federal Highway Administration (FHWA)

– Ben Graybeal

> Proprietary mixes with 2% fiber content

> Compressive strength: 17 to 29 ksi

> Modulus of elasticity: 𝐸𝑐 = 46200 𝑓′𝑐 𝑝𝑠𝑖

> Tensile strength: 𝑓𝑡 = 6.7 𝑓′𝑐 𝑢𝑛𝑡𝑟𝑒𝑎𝑡𝑒𝑑 (psi)

𝑓𝑡 = 8.2 𝑓′𝑐 𝑠𝑡𝑒𝑎𝑚 𝑐𝑢𝑟𝑒𝑑 (𝑝𝑠𝑖)

Material Properties

16

Overview

> Introduction

> Previous Work





> Conclusions


> Acknowledgements

17

Research Motivation

> Rehabilitation

– Strengthening of an existing steel girder using UHPC encasement

Industry Applications

18

Graybeal, Benjamin A., et al. “Properties and Behavior of UHPC-Class Materials.” FHWA, 2018.

Research Motivation

> Girders

– Comparison of typical prestressed bridge girders composed of conventional concrete and UHPC

Industry Applications (cont.)

19


Research Motivation

> Connections

– Bridge deck

– Pier cap

Industry Applications (cont.)

20


Overview

> Introduction

> Previous Work





> Conclusions


> Acknowledgements

21

Experimental Program

> Evaluate the shear strength of UHPC.

> Determine the effect of fiber content on the behavior of UHPC by varying the percentage of fibers in UHPC batches.

> Determine the effect of material sourcing on the behavior of UHPC.

Research Objectives

22


Testing Plan

23

University of Washington Testing Plan

Test Dimension (in) Test Day Reference

Compression Cylinder 4x8 3 @ 3, 60 ASTM C39

Modulus of Elasticity 4x8 3 @ 60 ASTM C469

Direct Tension 3.5x2x12 3 @ 60

Flexural Beam 3x3x11 3 @ 60 ASTM C78

Pure Shear 35x35x2.75 1 @ 60


University of Oklahoma Mix Design

24

University of Oklahoma Mix Design

Material Per yd3 Unit Supplier

Type 1 Cement 1179.6 lb Ash Grove (Chanute, KS)

Slag 589.8 lb Holcim (Chicago, IL)

Silica Fume 196.6 lb Norchem (Beverly, OH)

Fine Masonry Sand 1966 lb Metro Materials (Norman, OK)

Steel Fibers (Dramix OL 13/0.2) 255.2 lb Bekaert

Superplasticizer (Glenium 7920) 15.77 oz/cwt BASF

Water 0.2 w/cm


University of Washington Mix Design

25

University of Washington Mix Design

Material Per yd3 Unit Supplier

Type 1 Cement 1179.6 lb Salmon Bay Sand & Gravel (Seattle, WA)

Slag 589.8 lb Lafarge (Seattle, WA)

Silica Fume 196.6 lb Salmon Bay Sand & Gravel (Seattle, WA)

Fine Masonry Sand 1966 lb Salmon Bay Sand & Gravel (Seattle, WA)

Steel Fibers (Dramix OL 13/0.2) 255.2 lb Bekaert

Superplasticizer (Glenium 7920) 20.7 oz/cwt BASF

Retarder (Daratard-40) 5.66 oz/cwt Grace Construction Products

Water 0.2 w/cm *Including admixture water


Specimen Plan

26

University of Washington Specimen Plan

Test Series Batch Name Fiber Content (%) Material Source

0UW2A 2 UW

UW2B 2 UW

1

UW2C 2 UW

UW2D 2 UW

UW2E 2 UW

2 UW1 1 UW

3 OU2 2 OU


> UW Panel Element Tester

Pure Shear

27

6 ft


> UW Panel Element Tester

Pure Shear (cont.)

28


> Panel specimen (3’ x 3’ x 2.75”)

Pure Shear (cont.)

29


> Panel specimen (3’ x 3’ x 2.75”)

Pure Shear (cont.)

30


> Instrumentation

Pure Shear (cont.)

31

Overview

> Introduction

> Previous Work





> Conclusions


> Acknowledgements

32

Experimental Results

Summary of Results

33

UHPC Strength Results

Batch Compression (psi) EMod (ksi) Tension (psi) Flexure (psi) Shear (psi)

UW2A N/A N/A N/A N/A N/A

UW2B 124 5,279 656 2495 1,063

UW2C 18,710 N/A N/A N/A 1,289

UW2D 20,160 5,744 1,194 2,857 1,414

UW2E 19,435 5,686 709 2,437 1,437

UW1 19,290 5,308 676 1,871 1,070

OU2 19,300 6,106 969 2,640 1,347


Pure Shear Test Results (UW2E)

34



35



36


Pure Shear Test Results

37

0 0.05 0.1 0.15 0.2 0.25

Shea

r St

ress

(p

si)

Crack Width (in)

Shea

r St

ress

(p

si)

Crack Slip (in)

Shea

r St

ress

(p

si)

Cra

ck W

idth

(in

)

Crack Slip (in)


Summary of Results based on Test Series

38

UHPC Strength Results

Test Series Compression (psi) EMod (ksi) Tension (psi) Flexure (psi) Shear (psi)

1 19,435 5,715 951 2,654 1,381

2 19,290 5,308 676 1,871 1,070

3 19,300 6,106 969 2,640 1,347

> Test Series 1: UW2C, UW2D, UW2E

> Test Series 2: UW1

> Test Series 3: OU2


Material Test Results based on Fiber Content

39

1% vs. 2% FiberCompressive Strength and Modulus of Elasticity: no differenceTensile and Flexural Strength: 30% reduction


Pure Shear Test Results based on Fiber Content

40

1% vs. 2% FiberShear Stress: 20% reductionCrack Width and Crack Slip: larger

Overview

> Introduction

> Previous Work





> Conclusions


> Acknowledgements

41

Comparison of Results

Summary of Results

42

Naming Convention

Batch Days Fiber (%)Student

ResearcherInstitution

Material

Sourcing

UW 60 1, 2 Voytko UW UW

OU 60 2 Voytko UW OU

C-OU 28 0, 1, 2, 4, 6 Campos OU OU

D-OU 28 0, 1, 2, 4, 6 Dyachkova OU OU

D-FIU 28 0, 1, 2, 4, 6 Dyachkova OU FIU


Compression

43

• Compressive strength increases as fiber content increases• D-OU does not show a big increase from 0 to 6% fibers


Modulus of Elasticity

44

𝐸𝑐 = 46200 𝑓′𝑐 (𝑝𝑠𝑖)

• Modulus of elasticity constant slightly increases as fiber content increases


Direct Tension

45

𝑓𝑡 = 6.7 𝑓′𝑐 𝑢𝑛𝑡𝑟𝑒𝑎𝑡𝑒𝑑 (psi)

𝑓𝑡 = 8.2 𝑓′𝑐 𝑠𝑡𝑒𝑎𝑚 𝑐𝑢𝑟𝑒𝑑 (𝑝𝑠𝑖)

• Tensile strength constant increases as fiber content increases• C-OU constant decreased from 4 to 6% fibers


Flexural Beam

46

• Flexural strength increases as fiber content increases• D-OU strength decreased from 4 to 6% fibers• Flexural Strength less scattered than Tensile strength


Tensile Strength (Direct Tension vs. Flexural Beam)

UHPC Tensile Strength Results

Batch Fibers (%) 𝑓𝑡𝑑 (psi) 𝑓𝑡𝑓 (psi)

UW2D 2 1,194 831

UW2E 2 709 880

OU2 2 969 811

2% Average 957 840

2% Standard Deviation 199 29

UW1 1 676 624


Pure Shear vs. Tensile Strength (Flexural Beam Test)

49

UW1

OU2

Overview

> Introduction

> Previous Work





> Conclusions


> Acknowledgements

50

Conclusions

> Fiber Content

– Fiber content had little effect on compressive strength and modulus of elasticity.

– Fiber content had large effect on tensile strength, flexural strength, and shear strength.

> Mixing procedure

– UHPC was extremely sensitive to mixing procedure.

– Mixing UHPC requires significantly more energy than conventional concrete.

– A high energy mixer would yield more consistent results.

Conclusions

51

Conclusions

UHPC Shear Estimation

52

UHPC Proposed Equation

Shear Strength 𝑣 = 46 𝑓𝑡 (𝑝𝑠𝑖)

𝑣 = 𝑠ℎ𝑒𝑎𝑟 𝑠𝑡𝑟𝑒𝑛𝑔𝑡ℎ

𝑓𝑡 = 𝑡𝑒𝑛𝑠𝑖𝑙𝑒 𝑠𝑡𝑟𝑒𝑛𝑔𝑡ℎ

Overview

> Introduction

> Previous Work





> Conclusions


> Acknowledgements

53

Recommendations for Future Work

> Build on the work completed by Floyd, Azizinamini, Graybeal, and others

> Test UHPC specimens with varying fiber content

– Percentage, shape, size, material

> Optimize UHPC mix design

– Fibers, admixture

> Cost-benefit analysis of UHPC in industry

> Investigate ductility of UHPC

> Conduct more pure shear tests on UHPC to create a database of results

> Model shear response of UHPC with available software (such as Vectr)

Recommendations

54

Overview

> Introduction

> Previous Work





> Conclusions


> Acknowledgements

55

Acknowledgements

> Funding and Collaboration

– Accelerated Bridge Construction (ABC-UTC) at Florida International University

– University of Oklahoma

> PI’s

– John Stanton

– Paolo Calvi

> Undergraduate assistants

– Ben Terry, Rueben Madewell, and Clayton Black

Thank You

56

behavior and strength of ultra-high performance concrete

Documents