Use of Steel Slag as a Geotechnical Material: Research and ... · Shear strength-Large-scale direct shear ... IndustrialResourcesCouncil.org 6 21 LDS Test ... Use of Steel Slag as

Use of Steel Slag as a Geotechnical Material: Research and Implenentation

Monica Prezzi & Irem Zeynap Yildirim -- 2012 Industrial Materials Conference -IndustrialResourcesCouncil.org 1

Use of Steel Slag as a Geotechnical Material – Research and

Implementation

Monica Prezzi and Irem Zeynep Yildirim

Industrial Materials Use in Sustainable Pavement Systems: State-of-the-Practice

Students Helen Santoso Meera Vasudevan

Funding INDOT/JTRP Multiserv Co. Edward C. Levy Co.

2Use of Steel Slag as a Geotechnical Material

GOAL: Find new, innovative uses for BOF and EAF steel slag in geotechnical applications

Publications Yildirim, I. Z., and Prezzi, M. (2009). "Use of Steel Slag in

Subgrade Applications." FHWA/IN/JTRP-2009-32/SPR-3129, Joint Transportation Research Program, Purdue University.

Yildirim, I. Z. (2009). "Experimental Study Of The Use of Steel Slag as a Geotechnical Material." Ph.D. Thesis, Purdue University.

Yildirim, I. Z., and Prezzi, M. (2011). “Chemical, Mineralogical, and Morphological Properties of Steel Slag,” Advances in Civil Engineering, vol. 2011, Article ID 463638, 13 pages doi:10.1155/2011/463638

Yildirim, I. Z., Santoso, H., Vasudevan, M., and Prezzi, M. (2012). "Use of Soil-Steel Slag-Fly Ash Mixtures in SubgradeApplications." FHWA/IN/JTRP-2012-32/SPR-3477, Joint Transportation Research Program, Purdue University.

3

Recyclable Materials

BOF and EAF steel slagTires/tire shreds Fly ash, bottom ash and ash mixtures

Foundry sandCrushed glassCement kiln dustConcrete materials from building demolition



Introduction Technical considerations

Mechanical behaviorSpecific characteristics of each material (lightweight/combustibility/volume instability/insulation properties)

Construction techniquesQuality controlQuality assuranceLong term behaviorEnvironmental impact

6

Sizing

•Coarse

(2.5”- 8”)64-203 mm

•Intermediate

(5/8” - 2.5”)16-64 mm

• Fine

(Minus 5/8”)0-16 mm

7

Motivation Almost no use for finer gradation steel slag

Problems related to volumetric instability

Problems related to disposal (stockpiling and land filling)

Limited research on the use of steel slag as a geotechnical material

1) Determine the geotechnical properties of BOF and EAF slag2) Develop a methodology to deal with the volumetric instability

problems3) Design mixtures suitable for geotechnical engineering applications

8

Testing Materials BOF slagMittal Steel, Indiana Harbour Works Plant

(Integrated mill with BF and BOF processing, BOF slag is processed by Multiserv)

Batch-1 Fresh BOF slag Batch-2 Fresh BOF slag Batch-2 Aged BOF slag (aging=1 year) Batch-3 Aged BOF slag (aging=1 year)

8



9

Testing Materials EAF(L) slagNucor Steel, Whitesville Mill(Mini Mill with EAF and LF processes, EAF(L) slag processed by Levy Co.)

Batch-1 Fresh EAF(L) slag Batch-2 Fresh EAF(L) slag Batch-2 Aged EAF(L) slag (aging=1 month)

10

Experimental ProgramEXPERIMENTAL PROGRAM FOR BOF AND EAF(L) SLAG SAMPLES

Index Properties

Grain-size distributionSoil classification Specific gravity

Absorption of the coarse aggregate

Mineralogy and Morphology

Chemical composition Mineralogy (X-Ray Diffraction)

Morphology (Optical Microscopy and SEM )

MechanicalBehavior

Compaction Maximum and minimum dry unit weight

Shear strength-Large-scale direct shear

-Triaxial

Swelling Potential Long-term CBR swelling

Environmental

Corrosivity potential-pH

-electrical resistivity Leachate characterization

11

Grain-Size Distribution

(ASTM D422-63)

12

Sieve Analyses of BOF Slag Samples

100.000 10.000 1.000 0.100 0.010 0.001Particle Size (mm)

0

20

40

60

80

100

Perc

ent F

iner

(%

)

Batch-1 Fresh BOF slagBatch-2 Fresh BOF slagBatch-2 Aged BOF slagBatch-3 Aged BOF slag

SILTGRAVEL SAND



13Grain-Size Distribution of Batch-1 Fresh BOF slag

100.000 10.000 1.000 0.100 0.010 0.001

Particle Size (mm)

0

20

40

60

80

100

Perc

ent F

iner

(%

)

Batch-1 Fresh BOF slag

SILTGRAVEL SAND

Poorly-graded sand with silt and gravel

14

Sieve Analyses of EAF(L) Slag Samples

100.000 10.000 1.000 0.100 0.010 0.001Particle Size (mm)

0

20

40

60

80

100

Per

cent

Fin

er (

%)

Batch-1 Fresh EAF(L) slagBatch-2 Fresh EAF(L) slag

SILTGRAVEL SAND

15Grain-Size Distribution of Batch-1 Fresh EAF(L) slag

100.000 10.000 1.000 0.100 0.010 0.001

Particle Size (mm)

0

20

40

60

80

100

Perc

ent F

iner

(%

)

Batch-1 Fresh EAF(L) slag

SILTGRAVEL SAND

Well-graded sand with silt and gravel

Specific Gravity of BOF and EAF (L) Slag

16

Sample ID

Batch-1 Fresh BOF slag 3.29

Batch-2 Fresh BOF slag 3.34

Batch-2 Aged BOF slag 3.32

Batch-3 Aged BOF slag 3.34

,s averageG

Average specific gravity of the BOF slag samples

Sample ID

Batch-1 Fresh EAF(L) slag 2.73

Batch-2 Fresh EAF(L) slag 3.04

,s averageG

Average specific gravity of the EAF(L) slag samples



17

Chemical CompositionBOF slag

Oxide Composition by %

CaO 39.40

FeO 30.23

SiO2 11.97

MgO 9.69

MnO 2.74

Al2O3 2.16

P2O5 1.00

TiO2 0.40

Na2O 0.25

Cr2O3 0.20

SO3 0.12

K2O 0.05

Cl 0.01

L.O.Ia 1.80

EAF(L) slagOxide Composition by %

CaO 47.52

Al2O3 22.59

FeO 7.61

MgO 7.35

SiO2 4.64

SO3 2.28

MnO 1.00

Cr2O3 0.37

TiO2 0.33

P2O5 0.09

Zn 0.06

K2O 0.02

Na2O 0.01

L.O.Ia 6.20a Loss on ignitiona Loss on ignition

18

Morphological Properties of BOF slag

Fresh and aged gravel-size BOF slag particles

Subrounded to subangular bulky particles with distinct asperities Rough surface texture

Gravel-size fresh BOF slag particles Gravel-size aged BOF slag particles

Agglomerates in aged BOF slag

19

Morphological Properties of EAF(L) slag

Subrounded to subangular bulky particles with distinct asperities Platy particles with very sharp edges Rough surface texture B-1 Fresh EAF(L) slag: particles with popcorn-like porous structure

Gravel-size particles from B-1 Fresh EAF(L) slag Gravel-size particles from B-2 Fresh EAF(L) slag

20

0 5 10 15 20 25

Axial Strain, 1(%)

0

200

400

600

800

1000

Dev

iato

ric s

tres

s (

' 1-

' 3) (k

Pa)

200 kPa110 kPa50 kPa

Triaxial Test Results - BOF Slag (aged)

0 5 10 15 20 25

Axial Strain, 1(%)

2

1

0

-1

-2

-3

-4

Vol

ume

tric

Str

ain

, v

(%)

200 kPa110 kPa50 kPa

EffectiveConfining Stress

Relative Compaction

Peak Friction Angle

Critical-stateFriction Angle

(kPa)

50 89% 47.3° ~41.1°

110 91% 45.2° ~39.6°

200 92% 43.5° ~40.2°

pR'c c



21

LDS Test Results - EAF(L) Slag Samples

0 100 200 300 400

Normal Stress (kPa)

0

100

200

300

400

500

She

ar S

tren

gth

(kP

a)

Batch-1 Fresh EAF(L) slag @R=95% and R=100%

c

0 100 200 300 400

Normal Stress (kPa)

0

100

200

300

400

500

She

ar S

tren

gth

(kP

a)

Batch-1 Fresh EAF(L) slag @R=95% and R=100%

c

0 100 200 300 400

Normal Stress (kPa)

0

100

200

300

400

500

She

ar

Str

eng

th (

kPa)

B-1 Fresh EAF(L) slag @w=10%, R=95% B-1 Fresh EAF(L) slag @ w=14%, R=100%

c- fitting parameters

67 kPa - 45.20 @ R=100%26 kPa - 44.50 @ R= 95%

Results for Batch-1 Fresh EAF(L) slag samples

Critical states Peak states

22

Swelling Tests

23

Swelling Tests Steel slag samples were prepared at their optimum moisture content

Samples were compacted to 97-100% relative compaction in CBR molds (Diameter=6in)

A steel mesh was placed in each container to give access to water from the bottom of the samples

Surcharge weight = ~2.5 kPa

Samples were soaked in water and swelling was monitored for ~ 17 months

25 mm -range dial gauge

Tripod

Extension rod

Adjustable stem of the perforated swell plate

Perforated swell plate

Annular Surcharge : 4.5 kg

25 mm -range dial gauge

Tripod

Extension rod

Adjustable stem of the perforated swell plate

Perforated swell plate

Annular Surcharge : 4.5 kg

(ASTM D1883)

24

Long-Term Swelling of BOF Slag

0 200 400

Time Elapsed (Days)

0

1

2

3

4

Vol

umet

ric

Str

ain,

v

(%)

B-1 Fresh BOF slagB-2 Fresh BOF slagB-2 Aged BOF slagB-3 Aged BOF slagB-3 Aged BOF slag

The swelling rates for the Batch-1 Fresh BOF slag:0-7 months 9.69x10-3 % /day7-10 months 1.08x10-2 % /day 10-13 months 3.22x10-3 % /day13-17 months 1.73x10-3 % /day

- max. swelling strain of 3.5%

Batch-2 Fresh and Batch-2 Aged BOF slag samples:

- max. swelling strains of 0.6% and 0.5%

Batch-3 Aged BOF slag samples:-max. swelling strains of 1.2-1.3%

Use of fresh BOF slag with fine gradation is detrimental

Aging alone is not sufficient to suppress swelling of the BOF slag samples tested



25

Long-Term Swelling of EAF(L) Slag

0 200 400

Time Elapsed (Days)

0

0.4

0.8

1.2

Vol

umet

ric S

trai

n,

v (%

)

B-2 Fresh EAF(L) slagB-2 Aged EAF(L) slag

Batch-2 Fresh EAF(L) slag:-initial 10 days 0.008%/day-10 days-17months 1.804x10-3%/day- max. swelling strain of 0.98%

Batch-2 Aged EAF(L) slag:-initial 10 days 0.01%/day-10 days-17months 1.556x10-3%/day- max. swelling strain of 0.83%

No stabilization was observed after 17 months of monitoring

Aging of the EAF(L) slag sample for one month reduced slightly the swelling rate

Aging alone was not sufficient to suppress the swelling of the EAF(L) slag samples tested

26

Steel Slag Mixtures

27

Steel Slag Mixtures

Class-C fly ash Ground rubber 10/20 (0.85-2mm range)(Rubber Mulch Products ,IN)(Nipsco Company, IN)

Materials used in Steel Slag Mixtures:

Strength gaincharacteristics

EAF(L) slag + Class-C fly ash mixturesBOF slag + Class-C fly ash mixtures

Swelling behaviorEAF(L) slag + Class-C fly ash mixturesBOF slag + Class-C fly ash mixturesBOF slag + ground rubber mixtures

28

Experimental ProgramEXPERIMENTAL PROGRAM FOR STEEL SLAG MIXTURES

Properties Tested Mixtures

CompactionCharacteristics

EAF(L) slag+ 5% Class-C fly ashEAF(L) slag+20% Class-C fly ash

Strength Gain Characteristics (UC tests)

EAF(L) slag+ 5% Class-C fly ashEAF(L) slag+10% Class-C fly ashEAF(L) slag+ 20% Class-C fly ash

Strength Gain Characteristics (UC tests)

BOF slag+ 5% Class-C fly ashBOF slag+10% Class-C fly ash

Swelling Behavior(Long-Term CBR Swelling Tests)

EAF(L) slag+ 5% Class-C fly ashEAF(L) slag+10% Class-C fly ashEAF(L) slag+ 20% Class-C fly ash

Swelling Behavior(Long-Term CBR Swelling Tests)

Fresh BOF slag+ 10% Class-C fly ashAged BOF slag+10% Class-C fly ashFresh BOF slag+ 10% ground rubberAged BOF slag+10% ground rubber



29Compaction Characteristics of EAF(L) Slag and Class-C Fly Ash Mixtures

0 4 8 12 162 6 10 14

Moisture content, w (%)

19.0

20.0

21.0

18.5

19.5

20.5

21.5

Dry

uni

t w

eig

ht, d

ry (

kN /

m3 )

Batch-2 Fresh EAF(L) slagBatch-2 Fresh EAF(L) slag + 5% Class-C fly ashBatch-2 Fresh EAF(L) slag + 20% Class-C fly ash

Sample ID

(%) (kN/m3) (pcf)

Batch-2 Fresh EAF(L) slag 11 20.02 127

Batch-2 Fresh EAF(L) slag +5% fly ash

10 19.92 124

Batch-2 Fresh EAF(L) slag +20 % fly ash

10 20.09 128

,maxd,maxdoptw

30

Unconfined Compression Tests(a) (b)

(c) (d)

(e) (f)

(a) (b)

(c) (d)

(e) (f)

(a) (b)

(c)

(d) Unconfined Compression Machine

LVDT

Load cell

(g) (h)

(i)

(j) Unconfined Compression Machine

LVDT

Load cell

(ASTM D5102-04)

Strain rate:0.75% /min.

4in (10cm)

8in

(20

cm)

1,2,4,7, 14 and 30 days

31

Unconfined Compression Tests

0 1 2 3 4 5

Axial Strain (%)

0

40

80

120

160

200

20

60

100

140

180

Axi

al s

tres

s (k

Pa)

After curing 1 dayAfter curing 2 daysAfter curing 3 daysAfter curing 7 days

Unconfined compression tests on Batch-1 Fresh EAF(L) slag samples

Batch-2 Fresh EAF(L) slag samples

Intact UC samples of Batch-1 Fresh and Batch-3 Aged BOF slag could not be recovered from the molds

32

Unconfined Compression Tests Dry mixtures were prepared with mixing steel slag and Class-C fly ash

The EAF(L) slag and Class-C fly ash mixtures were compacted at ~10% moisture content with standard proctor energy

Batch-2 Fresh EAF(L) slag + 5 % Class-C fly ash (by weight)Batch-2 Fresh EAF(L) slag + 10 % Class-C fly ash (by weight) Batch-2 Fresh EAF(L) slag + 20 % Class-C fly ash (by weight)

The BOF slag and Class-C fly ash mixtures were compacted at ~7% moisture contentwith standard proctor energy

Batch-3 Aged BOF slag + 5 % Class-C fly ash (by weight)Batch-3 Aged BOF slag + 10 % Class-C fly ash (by weight)



33UC Test Results for EAF(L) Slag and Class-C Fly Ash Mixtures

0 1 2 3 4 5Axial Strain (%)

0

400

800

1200

1600

2000

Axi

al S

tre

ss (

kPa)

After curing 1 dayAfter curing 2 daysAfter curing 4 days

After curing 7 daysAfter curing 14 daysAfter curing 30 days


0

1000

2000

3000

4000

Axi

al S

tre

ss (

kPa)



B-2 Fresh EAF(L) slag +

5% Class-C fly ash mixture





0

2000

4000

6000

8000

Axi

al S

tres

s (k

Pa)




20% Class-C fly ash mixture EAF(L) slag and 5, 10, 20% Class-C fly ash mixtures

0 10 20 30 40

Curing Time (days)

0

2000

4000

6000

8000

Unc

onfin

ed C

ompr

essi

ve S

tren

gth

(kP

a)

EAF(L) slagEAF(L) slag + 5% Class-C fly ash mixtureEAF(L) slag + 10% Class-C fly ash mixtureEAF(L) slag + 20% Class-C fly ash mixture


Unconfined compressive strength of EAF(L) Slag and Class-C fly ash Mixtures (kPa)

Curing time: 1 day 2 day 4 day 7day 14 day 30 day

Fresh EAF(L) slag + 5% Class-C Fly ash

810 842 932 986 1021 1866


1614 1804 2059 2387 2512 3833


4672 4871 6024 6255 7351 7905

Mixtures (kPa) (psi) R2

EAF(L) slag + 5% Class-C Fly ash = 725.75 t0.2086 = 105.26t0.2086 0.7354

EAF(L) slag + 10% Class-C Fly ash = 1532.2 t0.235 = 222.2 t0.2350 0.9281

EAF(L) slag + 20% Class-C Fly ash = 4587.2 t0.1666 = 665.32t0.1666 0.9695

qu=unconfined compressive strength; t=time (in days)

uq

uq

uq

uq

uq uq

Summary of the UC strength of EAF(L) slag Mixtures

Time vs. unconfined compressive strength gain of EAF(L) slag and Class-C fly ash mixtures

36UC Test Results - BOF Slag and Class-C Fly Ash Mixtures


0

500

1000

1500

2000

2500

Axi

al S

tre

ss (

kPa)



B-3 Aged BOF slag +



0

2000

4000

6000

Axi

al S

tre

ss (

kPa)



B-3 Aged BOF slag +




37UC Test Results - BOF Slag and Class-C Fly Ash Mixtures

0 10 20 30 40

Curing Time (days)

0

2000

4000

6000

8000

Unc

onf

ine

d C

ompr

essi

ve S

tren

gth

(kP

a) BOF slag + 5% Class-C fly ash mixtureBOF slag + 10% Class-C fly ash mixture

BOF slag and 5 and 10% Class-C fly ash mixtures

Unconfined Compressive Strength of BOF Slag and Class-C Fly ash Mixtures (kPa)

Curing time: 1 day 2 day 4 day 7day 14 day 30 day

Aged BOF slag + 5% Class-C Fly ash

675 915 1379 1447 1936 2328

Aged BOF slag + 10% Class-C Fly ash

2337 2873 3458 3768 4170 5874

Mixtures (kPa) (psi) R2

BOF slag + 5% Class-C Fly ash = 724.08 t 0.3628 = 104.99 t 0.3631 0.9714

BOF slag + 10% Class-C Fly ash = 2362.2 t 0.2496 =342.61 t 0.2496 0.9717uququq

uq

Time vs. unconfined compressive strength gain of BOF slag and Class-C fly ash mixtures

Summary of the UC strength of BOF(L) slag Mixtures

38

Swelling Tests

39Long-Term Swelling Tests on Steel Slag Mixtures Dry mixtures were prepared by mixing steel slag and Class-C fly ash or ground

rubber

The samples were compacted in CBR molds assembled with dial gauges

The steel slag samples were monitored for 9-15 months

Long-term CBR swelling tests were performed on the following mixtures:

Batch-2 Fresh EAF(L) slag + 5 % Class-C fly ash (by weight) Batch-2 Fresh EAF(L) slag + 10 % Class-C fly ash (by weight) Batch-2 Fresh EAF(L) slag + 20 % Class-C fly ash (by weight)

Batch-1 Fresh BOF slag + 10 % Class-C fly ash (by weight) Batch-3 Aged BOF slag + 10 % Class-C fly ash (by weight) Batch-1 Fresh BOF slag + 10 % ground rubber (by weight) Batch-3 Aged BOF slag + 10 % ground rubber (by weight)

40Long-Term Swelling Tests on EAF(L) Slag Mixtures

0 100 200 300 400 500

Time Elapsed (Days)

0

0.04

0.08

0.12

0.16

Vol

umet

ric S

trai

n,

v (%

)

B-2 EAF(L) slag + 5% Class-C fly ashB-2 EAF(L) slag + 10% Class-C fly ashB-2 EAF(L) slag + 20% Class-C fly ash

0 200 400

Time Elapsed (Days)

0

0.4

0.8

1.2

1.6

Vol

umet

ric S

trai

n,

v (%

)

B-2 Fresh EAF(L) slagB-2 Aged EAF(L) slagB-2 EAF(L) slag + 5% Class-C fly ashB-2 EAF(L) slag + 10% Class-C fly ashB-2 EAF(L) slag + 20% Class-C fly ash

Results of long-term swelling tests for EAF(L) slag and Class-C fly ash mixtures

Results of long-term swelling tests for all EAF(L) slag and EAF(L) slag and Class-C

fly ash mixtures



41Long-Term Swelling Tests on BOF Slag Mixtures

Results of long-term swelling tests for

BOF slag mixtures

Results of long-term swelling tests for

BOF slag and mixtures of BOF slag

0 100 200 300

Time Elapsed (Days)

0

1

2

3

Vol

umet

ric S

trai

n,

v (%

)

B-1 Fresh BOF slag+10% Class-C fly ashB-3 Aged BOF slag + 10% Class-C fly ashB-1 Fresh BOF slag + 10% ground rubberB-3 Aged BOF slag + 10% ground rubberB-1 Fresh BOF slagB-3 Aged BOF slag

0 100 200 300

Time Elapsed (Days)

0

1

2

3

Vol

umet

ric S

trai

n,

v (%

)

B-1 Fresh BOF slag+10% Class-C fly ashB-3 Aged BOF slag + 10% Class-C fly ashB-1 Fresh BOF slag + 10% ground rubberB-3 Aged BOF slag + 10% ground rubber

42Summary of Results for Steel Slag Mixtures Compaction characteristics:

EAF(L) slag and 5% Class-C fly ash mixture: wopt = ~10% dry = 19.9 kN/m3

EAF(L) slag and 20% Class-C fly ash mixture: wopt = ~10% dry = 20.1 kN/m3

The fresh EAF(L) slag and Class-C fly ash mixtures:-excellent strength gain with time- The two-day unconfined compressive strength formixtures with 5 % Class-C fly ash (by weight) 842 kPa

10% Class-C fly ash (by weight) 1804 kPa20% Class-C fly ash (by weight) 4871 kPa

The aged BOF slag and Class-C fly ash mixtures:-excellent strength gain with time- The two-day unconfined compressive strength formixtures with 5 % Class-C fly ash (by weight) 915 kPa

10% Class-C fly ash (by weight) 2873 kPa

43Summary of Results for Steel Slag Mixtures

Addition of 10% Class-C fly ash suppresses the swelling of both fresh and aged BOF slag samples significantly

Addition of 10% Class-C fly ash is more effective in stabilizing the swelling of BOF slag than the addition of 10% ground rubber

Addition of 5-10% Class-C fly ash suppresses the swelling of fresh EAF(L) slag almost completely

44

Conclusions BOF and EAF(L) slag have superior frictional properties and densities than

conventional soils

In the presence of water, fresh and aged BOF and EAF(L) slags increase in volume

Aging of BOF and EAF(L) slag is not sufficient to suppress swelling

BOF and EAF(L) slags do not show strong self-cementing properties

The UC strength of BOF and EAF(L) steel slag improved significantly with the addition of Class-C fly ash

Addition of 5-10% Class-C fly ash was effective in suppressing swelling of fresh EAF(L) slag

Addition of 10% Class-C fly ash was effective in suppressing swelling of fresh BOF slag

Both mixtures of BOF slag and Class-C fly ash and mixtures of EAF(L) slag and Class-C fly ash can be utilized effectively in geotechnical applications



Steel Slag ImplementationI65 -Crown Point, Indiana

(Soil + 7%Steel Slag +3%Class-C Fly Ash Mixture)

I-65 and 109th Avenue, Crown Point Indiana

46

Crown Point, IndianaCrown Point, Indiana

•Clayey in situ soils

Stabilizing Agent•Class-C fly ash (NIPSCO) •EAF steel slag fines (Edward C. Levy Co.)

Stabilizing Mixtures (by weight of soil) •5 % steel slag - 5 % Class C fly ash •8 % steel slag - 2 % Class C fly ash•7 % steel slag - 3 % Class C fly ash

In Situ Soils47

•Per AASHTO Soil Type: A-6 (PI=12-13)

• Average UC strength = 275 kPa (40 psi)

Proctor Compaction Tests48

8 12 16 20 2410 14 18 22

Moisture content, w (%)

15

16

17

18

19

20

16

17

18

19

20

Dry

uni

t wei

ght, d

ry (k

N /

m3 )

NW6 ClayNW6 Clay - 7% steel slag - 3% fly ash mixture

R2= 0.923

R2= 0.960

• Optimum Water Content = ~15.5% • Maximum Dry Unit Weight = 18 kN/m3 (114.3 pcf)



Unconfined Compression Tests

0 10 20 30

Curing Time (days)

0

300

600

900

1200

1500

Unc

onfin

ed C

ompr

essi

ve S

tren

gth

(kP

a)

NW6 Clay - 7% steel slag - 3% fly ash mixture

Swelling Tests50

uquququq

0 40 80 120

Time Elapsed (Days)

0

-0.1

-0.2

-0.3

-0.4

-0.5

Vol

umet

ric S

tra

in, v

(%

)

NW6 ClayNW6 Clay - 7% steel slag - 3% fly ash S-1NW6 Clay - 7% steel slag - 3% fly ash S-2

Ramp Prior to Stabilization51

•Truck used for uniformly spreading the slag- fly ash mixture on the subgrade

Spreading the Slag-Fly Ash Mixture

•Spreading the slag- fly ash mixture on the subgrade



Mixing

•Mixing the Slag-Fly Ash Mixture with in-situ soil

Mixing

•Mixing and checking moisture content using nuclear gauge

Compaction55

•Compacting with sheepsfoot roller and smooth-wheeled drum roller•Subgrade after compaction

Subgrade



Quality Control – Nuclear Gauge Density Tests

57 Quality Control – Dynamic Cone Penetration Tests

•Measurements for determining DCPT stations

•DCPT test in progress

59

DCP criteria (NDCP) for a penetration of 0 to 150 mm

(0 to 6 inch) (modified after Kim et al. 2010)

(a) DCP blow counts associated with a CBR of 8 (ILDOT 2005).(b) Iowa DOT classified the soil either “suitable soil” or “unsuitable soil” in each group of soil. The values show the ranges of it (Larsen et al. 2007).(c) The cri teria of sandy soil apply for “granular” base layer; MnDOT recorded NDCP values only for blow counts that are higher than two (Burnham 1997).(d) DCP blow counts associated with a CBR of 8 (Gabr et al. 2000).

Pavement Work

•Placement of reinforcement

•Cleaning



Preparation for Concrete Placement

•Layout of the new ramp

•Spraying the machines with form oil to prevent the concrete from sticking to the metal

Concrete Placement

•Transferring the concrete from the trucks to the ramp; concrete later placed by the vibrating machine

Concrete Placement63

• Placement of concrete: before and after the initial leveling by the vibratory equipment

Concrete Work

•Leveling the concrete



Concrete Work65

•Tinned concrete surface

Finishing Concrete Work

• Coating concrete surface with 1600-white, water-based, wax-based concrete curing compound

Acknowledgments Nayyar Zia Siddiki (INDOT) Barry Partridge (INDOT) John Yzenas (Edward C. Levy Co) Multiserv Co. Hobi Kim (Fugro Consultants) Helen H. Santoso Meera Vasudevan

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Thanks!



69

X-ray Powder Diffraction Data

20 40 6010 30 50

2 (deg)

0

400

800

1200

1600

200

600

1000

1400

Inte

nsi

ty(C

ou

nts

)

B-1 Fresh BOF slag X-ray diffraction patternB-3 Aged BOF slag X-ray diffraction pattern

20 40 6010 30 50

2 (deg)

0

1000

2000

3000

4000

500

1500

2500

3500

Inte

nsity

(Cou

nts)

B-1 Fresh EAF(L) slag X-ray diffraction patternB-2 Fresh EAF(L) slag X-ray diffraction pattern

CH

CC

C2S

C3S/C2S

MgO

Ca3Mg (SiO4)2

CaMg(CO3)2

Ca2Fe2O5

Ca12 Al14033

CH

C2S

CaO

MgO

MgSO4. 5H20

(Mg, Fe)CO3

70

X-ray Diffraction Analysis B-1 Fresh and B-3 Aged BOF slag

Well-defined overlapping peaks Very crystalline structure

Main Mineral Phases

Portlandite Ca(OH)2

Merwinite Ca3Mg(SiO4)2

Srebrodolskite Ca2Fe2O5

Minor and probable phases include:Lime CaODolomite CaMg(CO3)2

Calcite (Ca, Mn)CO3

Larnite Ca2SiO4

Periclase MgOMagnesite MgCO3

B-1 Fresh and B-2 Fresh EAF(L) slag

Well-defined overlapping peaks with very high intensities

Very crystalline structure

Main Mineral PhasesB-1 Fresh EAF(L) slag B-2 Fresh EAF(L) slag

Portlandite Ca(OH)2 Portlandite Ca(OH)2

Mayenite Ca3Mg(SiO4)2 Mayenite Ca3Mg(SiO4)2

Malenterite FeSO4.7H2O Periclase MgOMagnesite (Mg, Fe)CO3

Minor and probable phases include:B-1 Fresh EAF(L) slag B-2 Fresh EAF(L) slagLime CaO Lime CaOPericlase (MgO) Mayenite Ca3Mg(SiO4)2

Larnite Ca2SiO4 Larnite Ca2SiO4

Pentahydrite MgSO4.5H2O Pentahydrite MgSO4.5H2O Wollastonite (Ca, Fe)SiO3 Wollastonite (Ca, Fe)SiO3

71

0 10 20 30

Curing Time (days)

0

300

600

900

1200

1500

Unc

onfin

ed C

ompr

essi

ve S

tren

gth

(kP

a)

NW6 Clay - 7% steel slag - 3 % fly ash mix.NW6 Clay - 7% steel slag - 3 % blast furnace slag mix.

72

10 10020 30 40 50 60 70 80 90

Number of Blows (N)

0

5

10

15

20

25

30

35

40

45

50

Wat

er

Con

tent

(%

)

NW6 Clay-S2

NW6 Clay-S4NW6 Clay-S1NW6 Clay - 7% steel slag - 3% fly ash mixture

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