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Optimizing Concrete Pavement Mixes with Slag Cement Optimizing Concrete Pavement Mixes with Slag Cement WCPA Workshop February 12 th , 2015 Oshkosh, WI WCPA Workshop WCPA Annual Concrete Pavement Workshop Bruce Blair Presentation February 12, 2015 1 of 41
Transcript of Optimizing Concrete Pavement Mixes with Slag Cement · Slag cement performs very well up to 50%...
Optimizing Concrete Pavement Mixes with Slag Cement
Optimizing Concrete Pavement Mixes with Slag Cement
WCPA Workshop
February 12th, 2015
Oshkosh, WI
WCPA Workshop
WCPA Annual Concrete Pavement Workshop
Bruce Blair Presentation February 12, 2015 1 of 41
Today’s TopicsToday’s Topics
What is slag cement?How it is made
How it is used
What effect does slag cement have on concrete?
Environmental impacts
Performance characteristics
Projects
WCPA Annual Concrete Pavement Workshop
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What do you call it?What do you call it?
“Ground granulated blast-furnace slag”
“GGBFS”
“Slag”
“Slag Cement”
WCPA Annual Concrete Pavement Workshop
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Non-metallic product of an iron blast furnace
Granulated
What is slag cement?What is slag cement?
WCPA Annual Concrete Pavement Workshop
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Non-metallic product of an iron blast furnace
Granulated
Ground
Cementitious material
What is slag cement?What is slag cement?
SlagCement
WCPA Annual Concrete Pavement Workshop
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0
20
40
60
80
100
0 20 40 60 80 100
SiO
2
CaO
Portland
Slag
F Ash
C Ash
Silica Fume
Metakaolin
Al2O3
0
20
80
60
40
Chemistry of different materials
WCPA Annual Concrete Pavement Workshop
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Slag: Chemical PropertiesSlag: Chemical Properties
• Similar mineral oxides as portland cement, but in different proportions & phases
Note: Slag cement from a given source tend to be very consistent
SlagPortland Cement
SiO2, % 32-42 22Al2O3, % 7-16 4.1CaO, % 32-45 66MgO 5-15 1.2Fe2O3, % 0.1-1.5 3.2
WCPA Annual Concrete Pavement Workshop
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Slag Cement ReactionsSlag Cement Reactions
Slag Cement + Ca(OH)2+
Water From
Portland Cement
Calcium-Silicate Hydrate (Additional)
Slag Cement + Alkalis +
Water
Calcium-Silicate Hydrate
Hydraulic Reaction
From Portland Cement
WCPA Annual Concrete Pavement Workshop
Bruce Blair Presentation February 12, 2015 8 of 41
Slag Cement ReactionSlag Cement Reaction
Portland Cement Concrete System
Portland-Slag Cement Concrete System
Aggregate
Portland CementSlag Cement
AggregateVoidsand
Ca(OH)2
Calcium Silicate Hydrate
WCPA Annual Concrete Pavement Workshop
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Slag Cement in Concrete -Standard SpecificationsSlag Cement in Concrete -Standard Specifications
Slag cement as a constituent of blended cementASTM C595 or AASHTO M 240 Standard Specification for Blended Hydraulic Cements
Type IS(35) = 65% PC + 35% SlagType IT(S25)(P15) = 60% PC + 25% Slag + 15% PozzolanType IT(S25)(L10) = 65% PC + 25% Slag + 10% Limestone
Slag cement as a SCM in concreteASTM C989 or AASHTO M 302 Standard Specification for Slag Cement for Use in Concrete and Mortar
WCPA Annual Concrete Pavement Workshop
Bruce Blair Presentation February 12, 2015 10 of 41
Min. 28-day Index*
% of Reference
Grade 80 75
Grade 100 95
Grade 120 115
Performance benefits of slag cement are achievable with all grades Trial batches determine appropriate proportions for desired concrete
performance characteristics
Slag-Activity Index and Grades(ASTM C989 and AASHTO M 302)Slag-Activity Index and Grades(ASTM C989 and AASHTO M 302)
* Average of 5 consecutive samples
WCPA Annual Concrete Pavement Workshop
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Slag Cement in ConcreteSlag Cement in Concrete
Typical– binary mixtures:25% to 50% for most general, structural applications, paving, precast and concrete product applications
Up to 65% for high-durability/strength mixes
Up to 80% for mass concrete
Typical– ternary mixtures:Portland (60-40%)/Slag Cement (25-35%)/Fly Ash (15-25%)
Portland (72-48%)/Slag Cement (25-45%) /Silica Fume (3-7%)
WCPA Annual Concrete Pavement Workshop
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Environmental - Life Cycle Inventory for Portland vs. Slag CementsEnvironmental - Life Cycle Inventory for Portland vs. Slag Cements
Item Units *Portland Cement
*Slag Cement
Virgin Material lb/ton 2,851 -
Energy MBTU /ton 4.57 0.62
Carbon Dioxide lb/ton 1,801 42
*These are typical numbers
WCPA Annual Concrete Pavement Workshop
Bruce Blair Presentation February 12, 2015 13 of 41
Environmental SavingsMaterial, Energy and Greenhouse GasEnvironmental SavingsMaterial, Energy and Greenhouse Gas
7%
24%
31%
10%
34%
45%
15%
37%
46%
13%
42%
59%
0%
10%
20%
30%
40%
50%
60%
70%
Raw Material Energy Carbon Dioxide
Savi
ngs
(Per
cent
)
Ready Mix (35% Slag) Ready Mix (50% Slag)
Precast (50% Slag) Mass (80% Slag)
WCPA Annual Concrete Pavement Workshop
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Effects of Slag Cement on Concrete PropertiesEffects of Slag Cement on Concrete Properties
Plastic Properties
Setting Time
Heat of Hydration
Color
Strength
Durability
WCPA Annual Concrete Pavement Workshop
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Reduced Water DemandReduced Water Demand
•Reduces water demand in concrete, typically by 0% to 5% with slag cement
•Also tends to have better slump retention
WCPA Annual Concrete Pavement Workshop
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Reduced Water DemandReduced Water Demand
0
2
4
6
8
10
300 320 340 360
Water Content (lb/cy)
Slum
p (in
)
100% Portland50% Slag Cement
water required to produce a 4” to 6” slump
WCPA Annual Concrete Pavement Workshop
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Plastic Properties
Slag cement• Improves pumpability• Improves workability• Easier to place, consolidate and finish
WCPA Annual Concrete Pavement Workshop
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Effects on Setting TimeEffects on Setting Time
0
2
4
6
8
10
12
Type I Type IS(25) Type IS(25)+15C Type IS(25)+15F
Initi
al S
et,h
r.
50F (10C)73F (23C)92F (33C)
WCPA Annual Concrete Pavement Workshop
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Effect of Slag Cement on Heat of HydrationEffect of Slag Cement on Heat of Hydration
0
10
20
30
40
50
60
70
80
90
0 50 60 70 80 90
Hea
t of H
ydra
tion,
cal
/g
Percentage of Slag Cement
WCPA Annual Concrete Pavement Workshop
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Temperature Rise – 20-ft. (6-m) Mass PlacementTemperature Rise – 20-ft. (6-m) Mass Placement
0102030405060708090
020406080
100120140160180200
0 5 10 15
Tem
pera
ture
, C
Tem
pera
ture
, F
Days After Casting
OPC
50% Slag Cement
70% Slag Cement
WCPA Annual Concrete Pavement Workshop
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ColorColor
• Slag cement enhances the lightness and brightness of concrete
• Lighter concrete• provides greater safety on streets and parking lots due to higher
reflectivity
• Lighting requirements may be reduced
• reflects more light, reducing the “urban heat island” effect
• Slag cement reduces efflorescence by reduced permeability and increasing the consumption of calcium hydroxide and alkalis
Portland vs. Slag cement concrete
WCPA Annual Concrete Pavement Workshop
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Concrete Performance: Binary System Compressive StrengthConcrete 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)
100% Portland
25% Slag Cement
50% Slag Cement
Lower early strengths, but better later strengths (typical crossover 7 to 14 days)
WCPA Annual Concrete Pavement Workshop
Bruce Blair Presentation February 12, 2015 23 of 41
Compressive Strength Blended Cement – Type IS(25)Compressive Strength Blended Cement – Type IS(25)
0
20
40
60
80
100
120
140
0 7 14 21 28
Stre
ngth
as
Per
cent
of T
ype
I at
28
day
s
Age, days
Type I
Type IS(25)
Nominal Propertiesw/cm = 0.45565 pcy (335 kg/m3) cementitious material4-in. (100-mm) slump6.5% air content
Moist cured 4x8-in. (100x200-mm) cylindersType I strength at 28 days = 6120 psi (42 MPa)
WCPA Annual Concrete Pavement Workshop
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Compressive Strength Development – Ternary SystemsCompressive Strength Development – Ternary Systems
0
20
40
60
80
100
120
140
0 7 14 21 28
Stre
ngth
as
Per
cent
of T
ype
I at
28
day
s
Age, days
Type I
Type IS(25)+15C
Type IS(25)+15F
Nominal Propertiesw/cm = 0.45565 pcy (335 kg/m3) cementitious material4-in. (100-mm) slump6.5% air content
Moist cured 4x8-in. (100x200-mm) cylindersType I strength at 28 days = 6120 psi (42 MPa)
WCPA Annual Concrete Pavement Workshop
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Effect of Slag Cement on Flexural StrengthEffect of Slag Cement on Flexural Strength
0%
20%
40%
60%
80%
100%
120%
140%
7 28
Flex
ural
Str
engt
h,
% o
f 28
day
OP
C
Age, days
100% OPC
50% OPC/50% Slag Cement
OPC @28 days = 830 psi (5.7 MPa)Aggregate
MoreCalcium Silicate Hydrate
WCPA Annual Concrete Pavement Workshop
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Durability - Chloride PermeabilityASTM C1202Durability - Chloride PermeabilityASTM C1202
0
2,000
4,000
6,000
8,000
0% 25% 50%
Slag Cement Replacement (%)
Cha
rge
Pas
sed
(Cou
lom
bs)
W/C = 0.45
W/C = 0.55
W/C = 0.70
Aggregate
MoreCalcium Silicate Hydrate
WCPA Annual Concrete Pavement Workshop
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Effect of Slag Cement on Sulfate ResistanceEffect 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
OPC
25% Slag Cement
50% Slag Cement
180-day Limit
1-year Limit
ASTM C1012
WCPA Annual Concrete Pavement Workshop
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Slag Cement and Total Concrete Alkali LoadingSlag Cement and Total Concrete Alkali Loading
From Thomas and Innis, 1998
0.000.020.040.060.080.100.120.140.160.180.20
0.00 1.00 2.00 3.00 4.00 5.00 6.00
% E
xpan
sion
at 2
Yea
rs
Concrete Alkali Content, kg/m3
Control25% Slag35% Slag50% Slag65% Slag
• Concrete Prisms ~ ASTM C1293• Sudbury Aggregate
WCPA Annual Concrete Pavement Workshop
Bruce Blair Presentation February 12, 2015 29 of 41
Slag Cement and Total Concrete Alkali LoadingSlag Cement and Total Concrete Alkali Loading
0.000.020.040.060.080.100.120.140.160.180.20
0.00 1.00 2.00 3.00 4.00 5.00 6.00
% E
xpan
sion
at 2
Yea
rs
Concrete Alkali Content, kg/m3
Control25% Slag35% Slag50% Slag65% Slag
• Concrete Prisms ~ ASTM C1293• Sudbury Aggregate
From Thomas and Innis, 1998
WCPA Annual Concrete Pavement Workshop
Bruce Blair Presentation February 12, 2015 30 of 41
Deicer Salt Scaling Resistance Laboratory vs. FieldDeicer Salt Scaling Resistance Laboratory vs. Field
In field exposures:Slag cement performs very well up to 50% slag cement“Good” concrete will scale if not finished/cured properly
In laboratory studies:Scaling tends to increase with higher levels of slag cement or fly ashAt high levels of slag (>50%) or fly ash (>25%), scaling can reach a high level
Stoney Creek, Ontario Test Pavements
Dike
6 mm of salt solution onspecimen during freezing
ASTM C672 – Deicer Scaling Test
Test Specimen
WCPA Annual Concrete Pavement Workshop
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Deicer Salt Scaling Resistance ACI 318 – Building Code RequirementsDeicer Salt Scaling Resistance ACI 318 – Building Code Requirements
Cementitious Materials Maximum % of Total Cementitious Materials Deicing Chem. Exposure
Slag cement, ASTM C989 50
Fly ash/other pozzolans, ASTM C618
25
Silica fume, ASTM C1240 10
Slag + Pozzolan + Silica Fume 50
Pozzolan + Silica Fume 35
WCPA Annual Concrete Pavement Workshop
Bruce Blair Presentation February 12, 2015 32 of 41
Use of Slag Cement with Portland-Limestone CementUse of Slag Cement with Portland-Limestone Cement
ASTM C595/AASHTO M 240 (first included in 2012 Editions)
5% to 15% limestone
Type IL(10) = 90% PC + 10% LS
Type IT(S35)(L10) = 55% PC + 35% Slag + 10% LS
Same physical requirements as existing C595/M240 cements
not permitted in moderate sulfate (MS) or high sulfate (HS) resistant blended cements
Note: WisDOT established a nominal replacement level of 10% limestone and allows the same SCM replacement levels as previously instituted
WCPA Annual Concrete Pavement Workshop
Bruce Blair Presentation February 12, 2015 33 of 41
Set Time – Compressive StrengthPC, PLC and Slag CementSet Time – Compressive StrengthPC, 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
Tim
e -m
inut
es
Com
pres
sive
Str
engt
h -P
SI
1 day 7 day 28 day Initial Set
WCPA Annual Concrete Pavement Workshop
Bruce Blair Presentation February 12, 2015 34 of 41
PC, PLC, and Slag Cement C1202 Chloride Ion Penetration PC, PLC, and Slag Cement C1202 Chloride Ion Penetration
0
1000
2000
3000
4000
5000
6000
7000
Type I-II Type IL 50IL/50S
Cou
lom
bs –
28
day
s
500 lb cement 564 lb cement
WCPA Annual Concrete Pavement Workshop
Bruce Blair Presentation February 12, 2015 35 of 41
Delaware DOT State Route 1Delaware DOT State Route 1
Built 1989-2004
1 Million cy concrete
35-50% slag cement
Mitigated ASR
Allowed use of local aggregates
WCPA Annual Concrete Pavement Workshop
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Miami Access Tunnel 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 lifeSulfate resistance and chloride penetration resistancef’c = 6,000 psi
WCPA Annual Concrete Pavement Workshop
Bruce Blair Presentation February 12, 2015 37 of 41
I-70 Mississippi River Bridge PylonsI-70 Mississippi River Bridge Pylons
St Louis Missouri-Illinois
1500-ft span
70% Slag cement - mass concrete
Exceeded 6000 psi f’c – often > 8000 psiPeak temperature of 119 F (met 150 F limit)
Triple Bottom LineEnhanced performanceConstruction efficiencyReduced Environmental Footprint
WCPA Annual Concrete Pavement Workshop
Bruce Blair Presentation February 12, 2015 38 of 41
Considerations for SpecificationsConsiderations for Specifications
Slag cement grades – performance benefits can be achieved with all grades
Total concrete alkali specifications for ASR – calculations are based on alkalis from portland cement
Consider use of ternary (and quaternary) cementitious systems, including portland-limestone cements
Provide for performance options
WCPA Annual Concrete Pavement Workshop
Bruce Blair Presentation February 12, 2015 39 of 41
Reduced environmental footprint
Raw materials
Energy
Greenhouse Gas
Improves concrete performance
Fresh Properties
Heat of Hydration
Long-term Strength
Durability
Use of Slag Cement for Sustainable and PerformanceUse of Slag Cement for Sustainable and Performance
WCPA Annual Concrete Pavement Workshop
Bruce Blair Presentation February 12, 2015 40 of 41
Thank You!Thank You!Slag Cement Association
38800 Country Club Drive
Farmington Hills MI 48331
(847) 977-6920
www.slagcement.org
WCPA Workshop
WCPA Annual Concrete Pavement Workshop
Bruce Blair Presentation February 12, 2015 41 of 41
