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

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

(c) Panel Element Tester

Project Contextualization3

𝑉𝑛 = 𝑉𝑐 + 𝑉𝑠 + 𝑉𝑝

Project Contextualization4

Project Contextualization5

Overview

> Introduction

> Previous Work

> Research Motivation

> Experimental Program

> Experimental Results

> Comparison of Results

> Conclusions

> Recommendations for Future Work

> Acknowledgements

6

Overview

> Introduction

> Previous Work

> Research Motivation

> Experimental Program

> Experimental Results

> Comparison of Results

> Conclusions

> Recommendations for Future Work

> 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

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Introduction

Steel Fibers

Spajic Machines- Steel Fibers

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Introduction

Steel Fibers

Spajic Machines- Steel Fibers

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13 mm long0.2 mm diameter

Introduction

UHPC

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

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Introduction

UHPC Properties

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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

> Research Motivation

> Experimental Program

> Experimental Results

> Comparison of Results

> Conclusions

> Recommendations for Future Work

> 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

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Overview

> Introduction

> Previous Work

> Research Motivation

> Experimental Program

> Experimental Results

> Comparison of Results

> Conclusions

> Recommendations for Future Work

> Acknowledgements

17

Research Motivation

> Rehabilitation

– Strengthening of an existing steel girder using UHPC encasement

Industry Applications

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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.)

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

Research Motivation

> Connections

– Bridge deck

– Pier cap

Industry Applications (cont.)

20

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

Overview

> Introduction

> Previous Work

> Research Motivation

> Experimental Program

> Experimental Results

> Comparison of Results

> Conclusions

> Recommendations for Future Work

> 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

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Experimental Program

Testing Plan

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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

Experimental Program

University of Oklahoma Mix Design

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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

Experimental Program

University of Washington Mix Design

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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

Experimental Program

Specimen Plan

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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

Experimental Program

> UW Panel Element Tester

Pure Shear

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6 ft

Experimental Program

> UW Panel Element Tester

Pure Shear (cont.)

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Experimental Program

> Panel specimen (3’ x 3’ x 2.75”)

Pure Shear (cont.)

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Experimental Program

> Panel specimen (3’ x 3’ x 2.75”)

Pure Shear (cont.)

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Experimental Program

> Instrumentation

Pure Shear (cont.)

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Overview

> Introduction

> Previous Work

> Research Motivation

> Experimental Program

> Experimental Results

> Comparison of Results

> Conclusions

> Recommendations for Future Work

> Acknowledgements

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Experimental Results

Summary of Results

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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

Experimental Results

Pure Shear Test Results (UW2E)

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Experimental Results

Pure Shear Test Results (UW2E)

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Experimental Results

Pure Shear Test Results (UW2E)

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Experimental Results

Pure Shear Test Results

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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)

Experimental Results

Summary of Results based on Test Series

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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

Experimental Results

Material Test Results based on Fiber Content

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

Experimental Results

Pure Shear Test Results based on Fiber Content

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

Overview

> Introduction

> Previous Work

> Research Motivation

> Experimental Program

> Experimental Results

> Comparison of Results

> Conclusions

> Recommendations for Future Work

> Acknowledgements

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Comparison of Results

Summary of Results

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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

Comparison of Results

Compression

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

Comparison of Results

Modulus of Elasticity

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𝐸𝑐 = 46200 𝑓′𝑐 (𝑝𝑠𝑖)

• Modulus of elasticity constant slightly increases as fiber content increases

Comparison of Results

Direct Tension

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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

Comparison of Results

Flexural Beam

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

Comparison of Results

Comparison of Results

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

Comparison of Results

Pure Shear vs. Tensile Strength (Flexural Beam Test)

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UW1

OU2

Overview

> Introduction

> Previous Work

> Research Motivation

> Experimental Program

> Experimental Results

> Comparison of Results

> Conclusions

> Recommendations for Future Work

> 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

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Conclusions

UHPC Shear Estimation

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UHPC Proposed Equation

Shear Strength 𝑣 = 46 𝑓𝑡 (𝑝𝑠𝑖)

𝑣 = 𝑠ℎ𝑒𝑎𝑟 𝑠𝑡𝑟𝑒𝑛𝑔𝑡ℎ

𝑓𝑡 = 𝑡𝑒𝑛𝑠𝑖𝑙𝑒 𝑠𝑡𝑟𝑒𝑛𝑔𝑡ℎ

Overview

> Introduction

> Previous Work

> Research Motivation

> Experimental Program

> Experimental Results

> Comparison of Results

> Conclusions

> Recommendations for Future Work

> 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

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Overview

> Introduction

> Previous Work

> Research Motivation

> Experimental Program

> Experimental Results

> Comparison of Results

> Conclusions

> Recommendations for Future Work

> 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

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