Issues Arising from UsingIssues Arising from UsingIssues Arising from Using Issues Arising from Using Supplementary Cementing Supplementary Cementing Materials in Cement Based Materials in Cement Based

FoamsFoamsFoamsFoamsFARNAZ BATOOL , MUHAMMAD MAMUN

AND

VIVEK BINDIGANAVILE*University of Alberta, Edmonton ,Canada

OUTLINEOUTLINE

IntroductionIntroductionProduction of Cement Based FoamsProduction of Cement Based FoamsR l t T t & E p i t l S t pR l t T t & E p i t l S t pRelevant Tests & Experimental Set up Relevant Tests & Experimental Set up Results & DiscussionResults & DiscussionConcluding RemarksConcluding Remarks

INTRODUCTIONINTRODUCTIONINTRODUCTIONINTRODUCTION

Cement Based Foams

Supplementary Cementing Materials

What are Cement Based Foams?What are Cement Based Foams?What are Cement Based Foams?What are Cement Based Foams?

Cement based foam is a light weight mixture of:- Cementitious material- Fine aggregate (for density higher than 800 kg/m3)- Water - Stable foam

Appli ti t pi ll i l d Applications typically include: - Engineered, non-structural fill- Precast panelsPrecast panels- Thermal and acoustic insulation - Refractory materials y

Cement Based Foams In AlbertaCement Based Foams In Alberta

Principal advantages:- High strength to weight ratio- Low demolition cost- Favourable thermal properties

Properties of Interest Rh l ( b lf l lli )- Rheology (must be self-levelling)

- Thermal Conductivity

Mix Constituents & Supplementary Mix Constituents & Supplementary Cementing MaterialsCementing Materials

Silica FumeFoaming agent

Polypropylene fibre

Portland cement (Type HE)

MetakaolinFly ash (class C)

(Type HE) 

Typical Mix Constituents Alternate SCM

Supplementary Cementing MaterialsSupplementary Cementing MaterialsSupplementary Cementing MaterialsSupplementary Cementing Materials

Fly ash (class C) was Chemical C i i % Fly Ash (Class C) Silica Fume Metakaoliny ( )

introduced at 20%, 25% and 50% of the binder.

Composition% Fly Ash (Class C) Silica Fume Metakaolin

Silicon Dioxide (SiO2)

35 90 51

Silica fume at 10% and 20%

Metakaolin at 10% and 20% f h bi d

Aluminum Oxide (Al2O3)

20 2 42

Ferric Oxide  5 2 0 50of the binder. (Fe2O3)5 2 0.50

Calcium Oxide (CaO) 20 0 0.35

Production of Cement Based FoamsProduction of Cement Based FoamsProduction of Cement Based FoamsProduction of Cement Based Foams

1. Foam GenerationDil d f i d i d i• Diluted surfactant is aerated using compressed air.

• Liquid-air combine is then forced to pass through a nozzle.2. Preparing the Slurry3. Flow Check for Target Density4. Adding the Foam to the Slurry

Ingredient Weight (%)

F tt Al h l 1 10Fatty Alcohol 1-10

Alcohol 6.5-35

Fatty Acid 10-65

Schematic of a foam generator

y

Composition of synthetic foaming agent

Components of the Foam GeneratorComponents of the Foam Generator

Liquid to N l

Liquid

Nozzle

qIntake

Air to Nozzlezz

100 Psi100 Psi Air Source

Sequence for Foam GenerationSequence for Foam Generation

foam1

3% foaming agent

f m

3

Nozzleair2

StepStep--1. Foam Production1. Foam Production

Stable foam coming out from nozzle

Foam ready to be mixed with slurry

Step 2. Preparing the Slurry

• Dry Powder of Cement and SCM is Mixed with Water.

M difi d D ill (P i Mi ) d f Mi i• Modified Drill (Paint Mixer) used for Mixing.

Cement, Water and SMC Mixing with Drill

Step 3. Flow Check for Target Density

Time taken for 350 ml of slurry to flow through the Marsh funnel relates to cast density.Besides density, this test also ensures flow-ability.

p g y

y y

152 mm

m30

5 mm

m50

.8 m

m

4 76 (ID)4.76 mm (ID)

Marsh Funnel Marsh Funnel Test

Step 4. Adding Foam to Slurry

Gradual mixing of foam and slurry. Addition of fibre reinforcement, if any. Check for cast density of foam concrete intermittently.

• Cast at 400, 600 and 800 kg/m3g

Slurry in rotary type mixer Mixing foam with slurry

Polypropylene Fibres

Property ValueFibre Length (mm) 20Fibre Length (mm) 20

Density ( kg/m3) 910Tensile Strength (MPa) 450

Modulus of Elasticity (MPa) 3450Modulus of Elasticity (MPa) 3450Denier 3

C i i f Mi E i dC i i f Mi E i dComposition of Mixes ExaminedComposition of Mixes ExaminedSCM Cast Density

kg/m3Cementkg/m3

Water kg/m3

SCMkg/m3

Foam kg/m3

Fibre (0.2% Vf)

20%Fly Ash 800 425 291 85 18 2320%Fly Ash 800 425 291 85 18 23

600 319 218 64 22 23

400 213 146 43 28 23

25% Fly Ash 800 408 291 102 18 23

600 306 218 77 22 23

400 204 146 51 28 23

50% Fly Ash 800 340 291 170 17 23

600 255 218 128 22 23

400 170 146 85 27 23

10% Silica Fume 800 464 291 47 17 2310% Silica Fume 800 464 291 47 17 23

600 348 218 35 22 23

400 232 146 24 27 23

20% Silica Fume 800 425 291 85 16 23

600 319 218 64 21 23

400 213 146 43 26 23

10% Metakaolin 800 464 291 47 17 23

600 348 218 35 22 23

400 232 146 24 27 23

20% Metakaolin 800 425 291 85 16 2320% Metakaolin 800 425 291 85 16 23

600 319 218 64 21 23

400 213 146 43 27 23

Tests Conducted

1. Compressive Test(ASTM C 39)

2. Thermal Conductivityy(ASTM D5334)

Foam ConcreteFoam ConcreteFoam Concrete Foam Concrete SpecimensSpecimens

Thermal TestCompressive Test

Size of cylinders 3in x 6in (75 mm x 150 mm) Size of cube 50 mm x 50 mm x 50 mm

Experimental Set UpExperimental Set Up

Th l P b N dl T t ASTM D 5334 th d iThermal Probe Needle Test ASTM D 5334 method is:

A transient heat method. Capable of determining the thermal conductivity & diffusivity of soil and soft Capable of determining the thermal conductivity & diffusivity of soil and soft rock. Suitable only for isotropic materials.

Applicable to dry materials over a wide temperature range from <0 to >100°C, depending on the suitability of the thermal needle probe construction to

temperature extremes.

Also used for specimens containing moisture.

Thermal ConductivityThermal ConductivityThermal ConductivityThermal Conductivity

Coefficeint of thermal expansion for cellular concrete varies Coe ce o e e p s o o ce co c e e v esdirectly with density

Typically 5.0 to 7.0 x 10-6 per o F ( 9.0 to 12.6 x 10-6 per o C)

Oven Dry Density Thermal Conductivity, K

lb/ft^3 kg/m3 BTU x in (h x ft2 x oF) w/(m x K)

20 320 0.75 0.11

30 480 0 91 0 1330 480 0.91 0.13

40 640 1.11 0.16

50 800 1.36 0.20

Typical thermal conductivity values for oven dry cellular concrete

Transient Line Source Thermal TestTransient Line Source Thermal TestTransient Line Source Thermal Test Transient Line Source Thermal Test (ASTM D 5334)(ASTM D 5334)

Schematic of electrical circuit and data acquisition system at the University of Alberta

Components of the Components of the Thermal Probe NeedleThermal Probe NeedleThermal Probe NeedleThermal Probe Needle

Base platform with axial heating source

Power Supply

Computerized data-acquisition

Sample PreparationSample Preparation

D illi th pl t d t thF t li d Drilling the sample to accommodate the thermal probe

Foam concrete cylinders

Testing of SpecimensTesting of Specimens

Sample mounted and ready for testingy g

Base platform with axial heating source

Calculation of Thermal ConductivityCalculation of Thermal ConductivityCalculation of Thermal Conductivity Calculation of Thermal Conductivity

Temperature of needle and time-history are recorded

Power supply values were recorded

Graph plotted between needle temperature and time (ln) in seconds

• Slope of the plot is calculated

Th l d i i K l l d f h bThermal conductivity K was calculated from the above

R l & Di iR l & Di iResults & DiscussionResults & Discussion

Effects of SCM on:a) Fresh Propertiesb) Compressive Strength of Hardened Samples

Effects of Thermal Conductivity on:a) 20 to 50% of Fly Ashb) 10 20 % f Sili Fb) 10 to 20 % of Silica Fumec) 10 to 20 % of Metakaolin

Effects of Supplementary Cementing M i lMaterials

Fresh PropertiesTime taken by slurry to flow through the funnel decreases with an increase in Fly Ash

Silica Fume and Metakaolin registered higher time-to-flow for the same cast density

SMC % of Replacement Materials

Marsh  Funnel Reading (s)

In particular, Metakoalin showed asignificant increases in time-to-flow

Fly Ash

20% 35-40

25% 34-39

50% 33-37

compared with Silica Fume for identicaldosage and density.

Uneven fibre dispersion was observed

Silica Fume10% 40-49

20% 60-64

10% 60-70

Uneven fibre dispersion was observedwith reduced flowability at higher dosageof SCM, in all cases.

Metakoalin 20%(7 ml HRWRA)

90-12054-60

Compressive Strength (1)

FLY ASH

12

14

16

18

engt

h (M

pa)

FLY ASH

Increased amount of Fly Ash reduces the compressive strength.

2

4

6

8

10 FA 50%

FA 25 %

FA 20%

ompr

essi

ve S

tre

Difficult to minimize the difference between cast and dry density specially for < 600 kg/m3.

00.21 0.31 0.42

Co y p y g

Relative Density

Compressive StrengthCompressive Strength (2)(2)p gp g ( )( )

12

14

16

th (M

Pa)

SILICA FUME

Increased amount of SilicaFume increases the compressivestrength

4

6

8

10

SF 10 %

SF 20 %

mpr

essi

ve s

treng

tstrength.

0

2

0.21 0.315

Com

0.42Relative Density

Compressive Strength (3)

Higher Dosage of Metakoalin increases the compressive strength.

Si ifi d i d i h d d i i ll f d iSignificant drop was noticed in the dry density specially for cast density less than 600 kg/m3.

Small sizes of samples should be avoided specially for lower density as it

16

18METAKOALIN

p p y yled to inconsistent dry density.

Mpa

)

10

12

14

16

MK 10 %essiv

e St

reng

th (M

2

4

6

8 MK 10 %

MK 20%

Com

pre

00.21 0.315 0.421

Relative Density

11 Fl A hFl A hEffect on Thermal Conductivity

1. 1. Fly AshFly Ash

/m/k

)

1.2000

1.4000

FLY ASH

The thermal conductivitydecreased with an increase

duct

ivity

(W/

0 6000

0.8000

1.0000

FA 20%

FA 25%

decreased with an increasein the fly ash fraction in thebinder.

erm

al Co

nd0.2000

0.4000

0.6000FA 50%

A linear relationship wasobtained between thermalconductivity and dry-density

Relative Density

The

0.00000.421 0.31 0.21

y y yas noted by otherresearchers.

Relative Density

2. Silica Fume

1.200

m/K

)

Silica FumeAn increase in the SilicaFume fraction of the binderl d d i h h l

0.800

1.000

ondu

ctiv

ity (w

/mled to a drop in the thermalconductivity.

0 200

0.400

0.600 SF 10 %

SF 20%

Ther

mal

Co

0.000

0.200

0.421 0.21

Relative Density

0.31

e at ve e s ty

3. 3. MetakoalinMetakoalin

1.200

1.400

Metakaolin

Thermal conductivity increased /m

/K

)

0.800

1.000

MK 10%

Thermal conductivity increasedwith an increase in Metakoalindosage in the binder. (Could this bedue to the Al2O3 component?)

Con

du

ctiv

ity

(W/

0.400

0.600

MK 10%

MK 20%

Th

erm

al C

0.000

0.200

0.42 0.31 0.21R l ti D itRelative Density

There was a linear relationshipbetween thermal conductivity and

Thermal Conductivity vs Relative density

dry density in all cases.

Concluding RemarksConcluding RemarksggIt is difficult to achieve desired dry density for cast density less than 600 kg/m3

oThis was further compounded for smaller specimens

Fly ash with 50% mix in general and 400 kg/m3 in particular was difficult to cast.

Where as the compressive strength decreased with an increase in the dosage of fly ash, silica fume and metakoalin led to an increase in the compressive strength, for the levels examined.

For Fly-Ash and Silica Fume the thermal conductivity decreased with an increase For Fly Ash and Silica Fume, the thermal conductivity decreased with an increase in dosage. On the other hand, metakoalin when used as an SCM led to an increase in the thermal conductivity of the foamed composite.

Exposure toExposure to SulphatesSulphatesExposure to Exposure to SulphatesSulphates

Sulphate Exposed (no fibre)Sulphate Exposed (no fibre)

Sulphate exposed samples exhibit adecrease in thermal conductivityimmediately upon exposure due toonset of cracking. Sustained exposureto sulphates beyond 30 days led to anincrease in the thermal conductivity.This is likely due to self-healingThis is likely due to self healing .

214

Thermal conductivity of plain (0.0% fibre) cement-based foams1

1.5

2

8

10

12

14

ess F

acto

r [ps

i]

ness

Fac

tor [

kPa]

Sulphate immersionWater immersion

Thermal conductivity of plain (0.0% fibre) cement based foamsafter immersion to sulphate bath and water bath for variousduration of exposure(457kg/m3).

0

0.5

1

0

2

4

6

Flex

ural

Tou

ghn

Flex

ural

Tou

ghn

000 7 15 30 60 90

Duration of Exposure [Days]

Sulphate Exposed (with fibre reinforcement)Sulphate Exposed (with fibre reinforcement)

Sulphate exposed samples with fibrereinforcement exhibit an increase in thethermal conductivity upon immediateexposure. This was attributed to crackarrest mechanisms effected through the

f i fibpresence of micro-fibres.

3240485664

250300350400450

ess F

acto

r [ps

i]

ss F

acto

r, [k

Pa]

Sulphate immersionWater immersion

Thermal conductivity of fibre reinforced (0.2%) cement-based foams after immersion to sulphate bath and water bath for various durations of exposure. (cast density = 475kg/m3). 0

8162432

050

100150200

0 7 15 30 60 90

Flex

ural

Tou

ghne

Flex

ural

Tou

ghne

s

f p ( y g )0 7 15 30 60 90

Duration of Exposure [Days]

Eff t fEff t f S l h tS l h tEffect of Effect of SulphatesSulphatesWhen exposed to a sulphate solution specimens with fibres haveWhen exposed to a sulphate solution, specimens with fibres have higher flexural toughness factor and thermal conductivity compared to an unexposed sample. These parameters drop only after 30 days of sustained exposure.y p

This may have a bearing on the choice of SCM, since that will lead to improved fibre-matrix bond.will lead to improved fibre matrix bond.

AcknowledgementsAcknowledgements

CEMATRIX Canada Inc., Calgary

City of Edmonton (Drainage Services)

NSERC Canada

El i ll C i f A iElastizell Corporation of America

THANK YOU!THANK YOU!