Georgia Chapter ACI Luncheon Benefits of Slag...
Transcript of Georgia Chapter ACI Luncheon Benefits of Slag...
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.
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
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 [email protected]