WOC 2010 Final Handouts

8/14/2019 WOC 2010 Final Handouts

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Sustainable Concrete and You

How to Survive and Thrive in the

Concrete Green Revolution


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AIA Credits

This program is registered with the AIA/CES for continuing professional education. As such, it doesnot include content that may be deemed or construedto be an approval or endorsement by the AIA of anymaterial of construction or any method or manner of

handling, using, distributing or dealing in any materialor product.Questions related to specific materials, methods and

services will be addressed at the conclusion of thispresentation.

Hanley Wood is a Registered Provider with The AmericanInstitute of Architects Continuing Education Systems. Credit earned on completion of this program will be reported toCES Records for AIA members. Electronic Certificates of Completion for all attendees available 6-7 weeks post show.


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Copyright Materials

This presentation is protected by US and Internationalcopyright laws. Reproduction, distribution, display anduse of the presentation without permission of the

speaker is prohibited.

Kevin A. MacDonald 2010


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Learning Objectives

Upon completing this program, the participant shouldbe able to:

1.Critically review concrete mixture proportions withrespect to the nature of the hydraulic binder present.

2.Explain the role of reduction of cement content inreducing the emissions of Carbon Dioxideassociated with concrete construction.

3.Make knowledgeable recommendations wherepozzolan contents can or should be raised or lowered.


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Where Are We Today?

Portland cement is (relatively) cheap andplentiful

Made from common materials Desirable properties are readily achieved


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So why disturb this situation?

The production of CO 2 occurssimultaneously with the production of cement

Estimates vary, but there is a generalagreement that about 5 to 10 percent of the worldwide emissions of due to CO 2

are from cement plants


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Cements which will setup and be resistantto the action of water

Pozzolans ACI definition Functional Definition Geographic Definition

Hydraulic Materials


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For our purposes, Silica Fume, Flyash andSlag are Po zzolans

Even Though Class C ash and Sla g areHydraulic Ce ments themselves

Pozzolans
http://d/CD%20Directory/1%20Concrete%20Tech/b%20SCM/MK1_016.jpghttp://d/CD%20Directory/1%20Concrete%20Tech/b%20SCM/MK1_016.jpghttp://d/CD%20Directory/1%20Concrete%20Tech/b%20SCM/MK1_016.jpghttp://d/CD%20Directory/1%20Concrete%20Tech/b%20SCM/MK2_006.jpghttp://d/CD%20Directory/1%20Concrete%20Tech/b%20SCM/MK1_016.jpghttp://d/CD%20Directory/1%20Concrete%20Tech/a%20Cement/MK2_072.jpg


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Natural Pozzolans

Industrial ByProducts Flyash GGBFS Silica Fume

Rice Hull Ash

Pozzolanic Materials


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SiO 2

Al 2O3CaO

Silica Fume

Metakaolin

Portland Cement

Glass

Class CFlyashGGBFS

Type F Flyash

NaturalPozzalans

Clay


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http://id-archserve.ucsb.edu/arthistory/152k/large_pictures/lgA69.1.htm


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http://id-archserve.ucsb.edu/arthistory/152k/large_pictures/lgA69.1.htm


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Concretes containing pozzolans havedifferent properties due to the chemicaland physical interaction

Initial use of these materials waseconomic

The best argument for their use is the

technical aspects of the concrete

Pozzolanic Materials


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ASTM C618 Class C High Calcium Class F - Low Calcium

Need new ( and better ) ways tocharacterize cement and flyash reactivity

Fly Ash


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FlyashParticles


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ASTM C 618 - Fly Ash & Natural

PozzolansClass N Natural PozzolanCalcined or uncalcined

Class F Fly AshFrom burning bituminous

or anthracite coalHas pozzolanic properties15% - 20% cement

replacementClass C Fly Ash

From burning sub-

bituminous or lignitecoalPozzolanic & cementitious

properties20% - 30% cement

replacement


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Premarc 1/18/07

Benefits of Fly AshBenefits of Fly Ash

Lower permeabilityLower permeabilityReduced shrinkageReduced shrinkageLower heat of hydrationLower heat of hydrationHigher ultimate strengthHigher ultimate strengthIncreased durabilityIncreased durabilityActs like ball bearings to improve flowability andActs like ball bearings to improve flowability and

workabilityworkabilityCost effectivenessCost effectivenessImprove sulfate resistance and ASRImprove sulfate resistance and ASRNot all fly ashes are the same !Not all fly ashes are the same !


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Class C ashes contain C 2S and

Will have some hydraulic action Can contribute Alkali (K+, Na+)

Class C Flyash


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Pozzolanic action alone Longer term strength gain over Class C Retards more than class C

Class F Ash


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SettingEffect Set Time of LMN Cement & ICF AshReplacements

Updated Data of New Lehigh Cement (8/1/03)Laboratory Condition

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

3:00 3:30 4:00 4:30 5:00 5:30 6:00 6:30 7:00

Age, hr:min

P e n e

t r a

t i o n

R e s

i s t a n c e ,

p s

i

LMN & 0% ash (3:45 / 5:40)

LMN & 10% ash (3:50 / 5:50)+0:05/+0:10

LMN & 20% ash(4:05 / 6:10)+0:20/+0:30

LMN & 30% ash (4:30 / 6:25)+0:45/+0:45


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Fly Ash ManufacturingFly Ash Manufacturing


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Flyash is not a constant

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

5500

6000

6500

7000

2:00 3:00 4:00 5:00 6:00 7:00 8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00

P e n e t r a t i o n R e s i s t a n c e , p s i

A e hr:m in

Mortar Fraction, 6 1/4 Bag, 0.45 W/C, 1490 lb SSDLLFA per C.YLM1 standard & 20% , 40% Replacement

2 0% ICF(4 :0 0 / 6:1 0) 4 0% ICF(5 :15 / 7:3 0)

20% MPC (6:40 / 9:45) 40% MPC(8:50 / 12:20)


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Extracted from the non-ferrous product of a Bessemer furnace

Material is cooled rapidly to trap slag inthe glass state

Consists mainly of aluminates andsilicates of Calcium

GGBFS


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Slag CementSlSl ag Cementag Cement

manufactured under manufactured under ASTM C 989ASTM C 989HydraulicHydraulic cementcementCo-productCo-pr oduct of a highlyof a highly

controlled metallurgicalcontrolled metallurgicalprocessprocessEnhances concreteEnhances concrete

propertiesproperties

Environmentally positiveEnvironmentally positivematerialmaterial


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Slag CementSlag CementDefinition: Finely ground

granulated materialoriginating from an iron blastfurnace and consisting of primarily calcium (CaO) andaluminum (AL 2O3) silicates(SiO 2) , used as a partialreplacement for portlandcement in concrete

Also known as:

Ground Granulated Blast-Furnace SlagGGBFSSlag


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Slag Cement HistorySlag Cement History

AspdinAspdinpatentspatentsportlandportlandcementcement

SlagSlagcementcement

producedproducedas aas aseparateseparatematerialmaterial

...18241824 1950s1950s 2000s2000s

SparrowsSparrowsPoint startsPoint startswidespreadwidespread

use inuse inEasternEastern

U.S.U.S.

LoriotLoriotmakesmakesslag-slag-limelime

mortar mortar

17741774 1890s1890s

First slagFirst slagportlandportlandblendedblendedcementscements

19821982

RapidRapid

expansionexpansionthroughoutthroughoutU.S.U.S.


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How Is Slag Produced?How Is Slag Produced?


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Premarc 1/18/07

Granulation Process

hot slag

High pressure water 6 - 10 tons water/ton slag

Slag is changed to glassy sand likesubstance known as granulated blastfurnace slag - GBFS


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Premarc 1/18/07


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Condensed molten siliceous material amorphous in nature

Product of the silicon and ferrosilicon smelting

industries Mean Diameter of 0.15m Specific Surface Area of 15000 20000 m 2/kg At 10 percent, there are 50000 to 100000

particles present for each grain of cement

Silica Fume


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350 kg of Cement 3000 m 2/kg 105000 m 2

8 percent silica fume 28 lb 560000m 2

Large Surface Forces result in verycohesive mixture

Large Surface area and high proportion of reactive material makes it extremelyreactive

Silica Fume


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Properties of Materials

Property SilicaFume

Slag Fly Ash

SpecificGravity 2.2 2.85 2.6-2.75

SpecificSurface

Very Fine Varies Finer thancement

Reactivity Very RapidVaries withsize andChemistry

Varies withsize andChemistry


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Chemically active Major and Minor Constituents Sulfate Form can be very important Solids must either dissolve in solution or a

surface reaction takes place

Cement Chemistry


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C3S

C2S

C3A C4AF

CaSO 4

Major Components


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Chemical reaction between individualclinker minerals, calcium sulfate andwater

Proceed at different rates in series andin parallel and influence one another

Hydration


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Cement + Water Glue and Ca(OH)2

Ca(OH)2 + Pozzolans More Glue

Pozzolanic Reaction


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High Volume Flyash Concrete

Significant increases in ASR, sulphate andthermal cracking resistance are possibleat 25 percent or higher flyash

replacement Problems with setting time and early age

strength gain


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High Volume Flyash Concrete

Minimum of 50 percent flyash by mass of cementitious materials

Low water content 130 kg/m3 Low cement content 200 kg/m3 Air entrained for freeze thaw 4500 psi, 6 inch or higher w/cm ~0.3 Below 4500 psi , w/cm ~ 0.4


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Comparisons to OPC Concrete

High Volume FlyAsh Concrete

Less energyintensivemanufacture

Higher ultimatestrength

More durableUses a waste by-

productLess global warminggases created

ConventionalConcrete

Energy intensivemanufacture

Weaker ultimatestrength

Less durableUses virgin materials

onlyMore global warming

gases created


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Plastic Properties

Low water content dictates use of Superplasticizer So slump is availableas required

Concrete is readily air entrained usingconventional admixtures

Workability is high, and fines content

promotes cohesion


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Plastic Properties

Bleeding - Negligible to very small Time of set may be significantly

increased depends on flyash beingused

Autogenous temperature rise peaktemperature is lower


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Hardened Concrete Properties

Strength Early age and later age strength

dependent on choosing the right cement

and flyash 1 day strength 900 to 1200 psi 28 day strength 4000 to 8000 psi routinely

available

Accelerators or type III Cement will give 1day strengths of 2500 psi or more


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Hardened Properties

Tensile strength and flexural strength arethe same as OPC Concrete

Modulus of Elasticity is high 35 GPa(~10 7psi)

Caused by infilling of the ITZ flyash asmicrofine aggregate


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Hardened Properties

Creep and Shrinkage Drying strains are lower than conventional

concrete Creep is lower than conventional concrete Likely due to denser microstructure


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Durability

Water Permeability Low Freezing and Thawing Behaves as

conventional air entrained concrete

Scaling resistance Some sidewalks havebeen constructed in Canada with goodreported performance. Others have notseen the same results. Should beavoided in deicer exposure


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Durability

Penetration of Chloride Ions Rapid Chloride Permeability

28 days 2500 coulombs passed 90 days 1000 coulombs passed 365 days 150 coulombs passed


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Durability

og Time

,

Charge

Passed

Coulombs

HVFA

i l ica Fume

1000

2000


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0

.0002

.0004

.0006

.0008

.001

.0012

.0014

.0016

C h e m i c a l S h r i n k a g e , m l / m l

Time, minut e

Mixture No .5

Mixture No .2

Mixture No .3

Mixture No .1

Mixture No .1

Mixture 5 100% OPCMixture 2 Slag: OPCMixture 3 Flyash:OPCMixture 1,10 FA:Slag:OPC


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Drying Shrinkage, 7 day cure

0.0005.001

.0015.002

.0025.003

.0035.004

.0045

0 5 10 15

Mix 1

Mix 2Mix 3

Mix 5

Log. (M ix2

Log. (M ix1

Log. (M ix5

Log. (M ix3

Time, Days

Shrinkage%

IncreasingPozzolanContent


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Chemical reaction between individualclinker minerals, calcium sulfate andwater

Proceed at different rates in series andin parallel and influence one another

Hydration


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Hydration Curve

Time

HeatEvolved,dH/dt


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Progress dependent on Rate of dissolution Rate of Nucleation and Crystal growth Rate of Diffusion of reagents through

hydration products

Hydration


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Water/Cement Ratio Curing Conditions and Humidity Hydration Temperature Presence of Admixtures

Hydration

Mi t P ti i d


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Mixture Proportioning andAdjustment


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Water Content

Water can be expressed in many ways:

Lb per cubic yard Gallons per cubic yard

Water cement ratio is not one of them


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550 lb cement and 220 lb water

660 lb cement and 264 lb water

Both have the same water : cement ratio


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Water Content will dictate the slump andworkability

Water:cement ratio will dictate the strengthand durability


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Water Cement Ratio

HighLow

The fluidity of a water-cement system is afunction of attractive and repulsiveforces between cement particles


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Workability Ease of Finishing


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Slump and Viscosity

Shear Stress

Shear Rate

Viscosity is slope of line


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Viscosity Models

.

0 +=

BinghamPlastic


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Bingham Model

Shear Stress

Shear Rate


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Viscosity Behavior

Shear Stress

Shear Rate

Viscosity is slope of line

WRDA

HRWRDA

SCC

Water


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Mixture Design - Rheology

0

Viscosity

2

10

20

Water

SuperPlasticizer

Air VMA

Flyash Slag*

Silica Fume


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Dispersion the water

reduction trickCapillaryPores

Gel

Pores


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Water:Cement Ratio

Controls the pore space

Lower w/c = fewer pores=less water


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Life-Cycle Costing


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Case Studies


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Great River Energy


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Freeze-Thaw Resistance

Freeze thaw resistance is imbued by air entrainment

Pozzolans do not change this low permeability ASTM C666 testing Very high class C may be detrimental

secondary crystallization


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Drying Period

Water in concrete can fill pores that oncedried cannot be refilled

So concrete may be more saturatedbefore drying than after immersionfollowing drying


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Scaling Resistance

Making the skin of concrete becauseconcrete beauty is skin deep


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f


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Modified Pore Structure

Gel pores Capillary Pores

0.001 0.01 0.1 110 Pore diameter, m

In

truded Volume

OPC

OPC +GGBFS

60 %Hydration

d f d


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Modified Pore Structure

Gel pores Capillary Pores

0.001 0.01 0.1 110 Pore diameter, m

In

truded Volume

OPC 3Days

OPC +GGBFS

28 days

60 %Hydration

Platinum LEED 45 percent


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Platinum LEED 45 percentreduction in cement content


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Flyash replacement of 60 percent Total cementitious content increased Net reduction 45 percent

I 35 W S A h F ll B id


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I 35 W St. Anthony Falls Bridge

All concrete in foundation andsubstructure is High Pozzolan Content

Conventional cementitious contents

less than 625 lb per cubic yard


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756


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319

783

756


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Thank You!

This concludes the American Institute of ArchitectsContinuing Education Systems Program.

Any Questions?Kevin A. MacDonald

1-800-CEMSTONE

WOC 2010 Final Handouts

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