Benefits of Slag Cement In Concrete October 28, 2015

Prepared by: Wayne Wilson – LafargeHolcim

Gardner Kavanagh & Gordon McLellan – Lehigh

John Melander – Slag Cement Association

Presenter: Ryan Betz, Argos Cement

Georgia Chapter ACI Luncheon

Today’s Topics

What Is Slag Cement Where does it come from How it is made How does it react Terminology

Specifications For Slag Cement ASTM C989 & AASTHO M 302 ASTM C595 & AASHTO M 240 DOT specifications

Slag Cement’s Effect On Concrete

Typical replacement values Effects on compressive strength Reducing permeability Sulfate attack Mitigation

Slag Cement and Environmental Initiatives

LEED v.4 Industry Average EPD LCA of Concrete Mixtures New LCA Tool

What Is Slag Cement?

A fine white powder that can be used as a SCM to enhance the properties of concrete In the presence of moisture exhibits hydraulic properties similar to portland cement

What Is Slag Cement?

Non-metallic molten material (slag) is diverted from the waste stream of iron ore blast furnace

Rapidly quenched to produce a glassy granulated product

Where does it come from?

Slag

What Is Slag Cement?

Granules are ground to a suitable fineness

Can be used in concrete mixtures to enhance strength, durability and sustainability

Slag Granules

Typically finer than portland cement

Slag Cement Reaction

Portland Cement Concrete System

Portland-Slag Cement Concrete System

Aggregate

Portland Cement Slag Cement

Aggregate Voids

and Ca(OH)2

Calcium Silicate Hydrate

What do you call it?

“Ground granulated blast-furnace slag”

“GGBFS” for short

“Slag”

“Slag Cement” Term used in ASTM and AASHTO standards

Not to be confused with “Air Cooled Slag”

Specification For Slag Cement

7-day Min. 28-day % of Reference % of Reference

Grade 80 ---- 75 Grade 100 Report 95 Grade 120 Report 115

ASTM C989 & AASHTO M 302

Reference mix = 100% OPC

Performance benefits can be achieved with all grades.

Slag activity determined by 50% P.C. + 50% Slag

Example labeling of blended cements with slag

Specification For Slag Cement

ASTM C595 & AASHTO M 240 Type IS(20)

Type IT(S20)(P10)

Type IT(S15)(L10)

Specifications GDOT

Section 430-Portland Cement Concrete Pavement If high early strengths are not desired, use granulated slag as a partial replacement for Portland cement in concrete. Follow these limits:

Replace the quantity of cement 50 percent or less by weight…

Section 500-Concrete Structures If high-early strengths are unnecessary, the Contractor may use granulated iron blast-furnace slag as a partial replacement for Portland cement in concrete if the following limits are met: a. Replace no more than 50 percent of the cement by weight. b. Replace the cement with slag at the rate of 1.0 lb (1.0 kg) of slag to 1.0 lb of cement.

University of Georgia Study

Conducting Slag Cement Related Study For GDOT Study Objective:

Provide specification recommendations to GDOT

Study will focus on slag cement and metakaolin

Reduction of dependence on fly ash through alternate SCM’s

Improve overall properties of concrete mixtures

Mass concrete designs

Specifications ALDOT

Section 450 - Portland Cement Concrete Pavement

Section 501 – Structural Portland Cement Concrete

Pinellas Bayway Bridge

65-ft clearance 4-lane bridge with 12-ft wide walkway replaced 2-lane drawbridge Slag cement used at 50% replacement in footings, columns, decks and barrier walls Met specified compressive strength 5500 PSI requirement and provided reduced permeability and durability required by Florida DOT for this marine exposure

Miami Access Tunnel

Access between the seaport and I-395 & I-95 Slag cement used in soil stabilization at 70% and in precast concrete liners at 51% Precast ternary mix design

150 year design life Sulfate resistance and chloride penetration resistance f’c = 6,000 psi

One World Trade Center

A world-class structure symbolic of courage and commitment to freedom Concrete performance requirements included:

Heat reduction in mass placements High strength – 14,000 psi Superior rheology Reduced environmental footprint

Concrete included a quaternary mixture containing 52% slag cement with portland cement, fly ash and silica fume

Concrete Performance: Binary System Compressive Strength

0

2,000

4,000

6,000

8,000

10,000

7 Day 28 Day

Com

pres

sive

Str

engt

h (p

si)

Portland 100%Slag Cement 25%Slag Cement 50%

Compressive Strength Development – Ternary Systems

0

20

40

60

80

100

120

140

0 7 14 21 28

Stre

ngth

as

Perc

ent o

f Ty

pe I

at 2

8 da

ys

Age, days

Type I

Type IS(25)+15C

Type IS(25)+15F

Nominal Properties w/cm = 0.45 565 pcy (335 kg/m3) cementitious material 4-in. (100-mm) slump 6.5% air content Moist cured 4x8-in. (100x200-mm) cylinders Type I strength at 28 days = 6120 psi (42 MPa)

Set Time – Compressive Strength PC, PLC and Slag Cement

0

50

100

150

200

250

300

350

0

1000

2000

3000

4000

5000

6000

7000

PC Type I PLC TypeIL(10)

PC 30% Slag IL(10) 30%Slag

Set T

ime

- min

utes

Com

pres

sive

Str

engt

h - P

SI

1 day 7 day 28 day Initial Set

Slag Cement and Reduced Permeability

What is permeability? Measure of how easy it is for water, air and other substances such as chloride ions to enter concrete Commonly measured by ASTM C1202 – rapid chloride permeability

How does slag cement affect permeability? Slag cement reacts with calcium hydroxide CA(OH)2 to create calcium silicate hydrate CSH reducing permeability

Why is it important? Low permeability concrete can reduce corrosion potential of embedded reinforcing steel

Low permeability can be achieved, in binary or ternary mixtures, with 25 to 65% slag cement substitution

Slag Cement replacement and ASTM C1202 Rapid Chloride Permeability

0

2,000

4,000

6,000

8,000

0% 25% 50%

Slag Cement Replacement (%)

Char

ge P

asse

d (C

oulo

mbs

)

W/C = 0.45W/C = 0.55W/C = 0.70

Slag Cement and Improved Sulfate Resistance

What is Sulfate Attack? A form of concrete deterioration caused by sulfates (SO4) Concrete in contact with some soils, salt water or wastewater Water soluble sulfates react with the hydration product of C3A and calcium hydroxide CA(OH)2 to create ettringite

Slag cement can be used to reduce sulfate attack potential

Slag cement does not contain C3A Reduces permeability Reacts with excess CA(OH)2 to create calcium silicate hydrate gel

Effect of Slag Cement on Sulfate Resistance

0.000.010.020.030.040.050.060.070.080.090.10

0 100 200 300 400

Expa

nsio

n, %

Age, days

OPC25% Slag Cement50% Slag Cement180-day Limit1-year Limit

ASTM C1012

Environmental Initiatives & Slag Cement – LEED v4

Use of slag cement in Product Specific EPD can differentiate your “Product” from others

Environmental Initiatives & Slag Cement – Product EPD

Slag Cement Association (SCA) in partnership with ASTM International, the program operator, developed Product Category Rules (PCR) PCR defines the rules and requirements for a slag cement EPD

PCR is posted at: http://www.astm.org/CERTIFICATION/DOCS/160.PCR_ASTM_Slag_Cement_PCR_090814.pdf

Environmental Initiatives – Industry Average Slag Cement EPD

The Industry Average Slag Cement EPD was issued May 2015 and is posted at http://www.astm.org/CERTIFICATION/DOCS/197.EPD_for_Slag_Cement_Association_Industry_Average_EPD_for_Slag_Cement.pdf

SCA commissioned Athena Sustainable Materials Institute to conduct an Industry Average LCA on Slag Cement in the USA and Canada, and to develop a Slag Cement Industry Average EPD in accordance with the Slag Cement PCR. SCA also commissioned ASTM to conduct critical review of LCA and verify EPD.

Slag Cement LCA Results – 1 metric tonne

LCA Results

Slag Cement relative to Ordinary Portland Cement & Portland Limestone Cement ....

0

0.2

0.4

0.6

0.8

1

1.2

OPC PLC SC

Global Warming Potential (kg CO2 equiv./kg)

0

1

2

3

4

5

6

7

OPC PLC SC

Primary Energy Consumption MJ /kg

OPC – 92% clinker, 3% limestone, 5% gypsum PLC – 82% clinker, 13% limestone, 5% gypsum

LCA Results for Ready Mixed Concrete

3,000 psi (20MPa) various design mixes with progressive use of slag cement

USA Average 3,000 psi mix, lbs. per cubic yard

Units 100%

Portland Cement**

US Average

Mix*

30% Slag Cement**

40% Slag Cement**

50% Slag Cement**

Portland Cement lbs. 486 455 340 292 243 Slag Cement lbs. 0 20 146 194 243 Fly Ash lbs. 0 88 0 0 0 Coarse Aggregate lbs. 1677 1633 1677 1677 1677 Fine Aggregate lbs. 1360 1368 1350 1347 1343 Water lbs. 261 302 261 261 261

* NRMCA Regional Benchmark LCA **NRMCA Industry Wide EPD www.nrmca.org/sustainability

LCA Results for Concrete

256 244 198 179 159

050

100150200250300

100%PortlandCement

USAverage

Mix

30% SlagCement

40% SlagCement

50% SlagCement

GWP - kg CO2e/cubic yard 3,000 psi Mix Design Possible savings... • 100 kg CO2 • 200 kg of resources • 500 MJ of energy

1758 1708

1656 1622 1588 1500155016001650170017501800

100%PortlandCement

USAverage

Mix

30% SlagCement

40% SlagCement

50% SlagCement

Non-Renewable Resource Use

kg/cubic yard 2014 1944 1707 1606 1504

0500

1000150020002500

100%PortlandCement

USAverage

Mix

30% SlagCement

40% SlagCement

50% SlagCement

Primary Energy Consumption MJ/cubic yard

LCA Results for FA & SC 3,000 psi Concrete

SCA Development of LCA Calculator

Utilizes SCA EPD and NRMCA industry average EPD

Can be used to compare different ready mix concrete design for various environmental impact

Ready Mixed Concrete LCA Calculator for Slag Cement

Slag Cement % Region20% 20% NRMCA

Adjust Slag Cement % Select Mix to Adjust Select Region

SCA Development of LCA Calculator

Concrete MixMix ID 2500 PSI 0% Slag Same mix with 20% Slag

Slag Cement (%) 0% 20%Strength (psi) 2500 2500

Portland Cement (lb) 429 343Slag Cement (lb) 0 86

Fly Ash (lb) 0 0Crushed Coarse Aggregate (lb) 1677 1677Natural Coarse Aggregate (lb) 0 0

Crushed Fine Aggregate (lb) 1408 1408Natural Fine Aggregate (lb) 0 0

Accelerating Admixture-Chlorides (oz) 20 20Air Entraining Admixture (oz) 1 1

Water Reducing Admixture - plasticizer (oz) 3 3High Range Water Reducing Admixture - superplasticizer (oz) 0 0

Water (gal) 31 31

NRMCA Benchmark mix design can be selected or mixes can be customized

SCA Development of LCA Calculator

Provides LCA properties comparison

Life Cycle Assessment ResultsMix ID 2500 PSI 0% Slag Same mix with 20% Slag

Climate Change (kg CO2-eq) 230.43 196.16Ozone depletion (kg CFC-11-eq ) 4.16E-06 4.17E-06

Acidification (kg SO2-eq ) 1.03 0.95Eutrophication (kg N-eq ) 0.13 0.12

Photochemical Ozone Creation/Smog (kg O3-eq ) 12.77 12.28Total primary energy consumption (MJ ) 1,844.52 1,664.47

Depletion of non-renewable energy resources (MJ ) 1,827.61 1,646.87Use of renewable primary energy (MJ ) 16.91 17.60

Depletion of non-renewable material resources (kg ) 1,742.71 1,685.72Use of renewable material resources (kg ) 0.53 0.58

Concrete batching water consumption (m3) 0.24 0.12Concrete washing water consumption (m3) 0.13 0.13

Total water consumption (m3) 0.37 0.25Concrete hazardous waste (kg) 0.31 0.31

Concrete non-hazardous waste (kg) 13.27 11.04

SCA Development of LCA Calculator

Tool can compare impact of mix designs on project Compares custom mixes to benchmark building

Reduces environmental impact of concrete mixtures

In Conclusion: Slag Cement

Widely accepted by various specifiers/ organizations

Can be used in conjunction with various cement and pozzolan types to achieve required strength

Is a recycled material from steel production process

Pinellas Bayway Bridge

Effective in reducing permeability and increasing durability of concrete

Thank You! Slag Cement Association

38800 Country Club Drive Farmington Hills MI 48331 (847) 977-6920 www.slagcement.org info@slagcement.org