Role of Admixture in Concrete

ROLE OF ADMIXTURESROLE OF ADMIXTURES

IN IN

READYMIX CONCRETE READYMIX CONCRETE

Contents

INTRODUCTION1

GLENIUM CONCRETE 2

SHRINKAGE REDUCING CONCRETE3

ULTRA HIGH STRENGTH CONCRETE4

CONCLUSION5

Admixtures?

What admixtures can do!

What Admixtures can do!

Chemical Admixtures

� ASTM C 494

� EN 934 – 2

� IS 9103:2003

Chemical Admixtures

Type Description

A Water Reducing admixture (WRA)

B Retarding Admixture

C Accelerating Admixture

D Water Reducing & Retarding Admixture

E Water Reducing & Accelerating Admixture

F High Range Water Reducing Admixture (HRWRA)

G High Range Water Reducing & Retarding Admix

MainMain effecteffect ofof plasticizingplasticizing admixturesadmixtures

1 2Higher workability at

constant w/c ratio

Increase of strength parameters through

reduction of w/c ratio at constant slump flow

Sl ump fl ow [cm]

with

Plasticizer

without

Plasticizer

Water/Cement Ratio

1

2

Types of concrete admixtures

� Lignosulphonates – LS

� Beta-Naphthalenesulphonate - Polycondensate – BNS

� Melamine-Sulphonate-Poly-condensate – MFS

� Poly Acrylates – PAC

� Polycarboxylate Ethers - PCE

Traditional Plasticizers/Superplasticizers

BNS molecules

ElectrostaticRepulsion

Mode of Action

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Ca2+ Ca2+

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Ca2+Ca2+Ca2+

Ca2+

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Ca2+

Ca2+

Ca2+

Ca2+

Ca2+

Ca2+

Ca2+

Ca2+Ca2+Ca2+

Ca2+

Ca2+ formation

of positively charged

surfaces

1. Step: surface charges (��positive zeta potential)Mode of Action

cem

ent gra

in

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negatively charged functional groups

provide water solubility and affinity to

positively charged surfaces

negatively charged functional groups

provide water solubility and affinity to

positively charged surfaces

2222ndndndnd step: adsorption of dispersantsstep: adsorption of dispersantsstep: adsorption of dispersantsstep: adsorption of dispersants

addition of 1st or 2nd generation

(super-)plasticizers

e.g. lignin sulfonates,

naphthalene-sulfonate-

formaldehyde resins

melamine-formaldehyde-sulfonate

resins

addition of 1st or 2nd generation

(super-)plasticizers

e.g. lignin sulfonates,

naphthalene-sulfonate-

formaldehyde resins

melamine-formaldehyde-sulfonate

resins

Mode of Action

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Ca2+

Ca2+

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cem

ent gra

in

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Ca2+

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Ca2+

Ca2+

Incorporation of superplasticizers

into growing hydrate phases

Incorporation of superplasticizers

into growing hydrate phases

Loss of dispersing effect!Loss of dispersing effect!

4444thththth step: loss of workability over timestep: loss of workability over timestep: loss of workability over timestep: loss of workability over timeMode of Action

1950 1960 1970 1980 1990 2000 2010

Volume of Admixtures

Conventional AE water-

reducing agent [Pozzolith]

High water-reducing

agent [Rheobuild]

AE high water-reducing agent

Super plasticizer [Glenium]

Innovation History of Water Reducer Technology

Year

PCE Molecule

� complex and flexible

molecules,

� comprising of main chain

� Side chains

� functional groups.

PCE Based - GLENIUM Molecules

GLENIUM molecules

Electrostatic and StericRepulsion

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ent gra

in

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ent gra

in

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ent gra

in

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ent gra

in

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Ca2+

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Ca2+

Ca2+

Ca2+

Ca2+

Ca2+

Ca2+

Ca2+

2nd generation:

polyether carboxylates

Coulomb and steric

repulsion

more effective!

1st generation:

Coulomb

repulsion only!

1st generation:

Coulomb

repulsion only!

Introduction ofIntroduction ofIntroduction ofIntroduction of

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Introduction ofIntroduction ofIntroduction ofIntroduction of

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Mode of Action

Glenium Concrete

� High grades

� Low Grades

� SCC

� Precast

Glenium Concrete for Higher Grades

Why higher grades? (M45 – M 60)

� Early destripping

� Advantages in column size reduction

� Longer spans and thinner decks

� PT slabs – 30 MPa in 3 days

General Practice for Higher Grade

� Use of Higher Cement contents

� Use of very low water /cement ratios

� Use of Expensive Mineral Admixtures

� Phenomenal increase in costs

� Concrete very sensitive to changes in moisture content

� Extra cement content due to retention effect

PT Slab requirements

� 30 MPa in 3 day

� Large pours to be done

� Voids & honeycombs cannot

be tolerated

� Constraint – Shrinkage,

which is sensitive to use of

higher cement content & SF

Critical Areas

� Use of higher cement content – Thermal Shrinkage

� Use of silica fume – Risk of Plastic shrinkage

� Use of low w/c ratio – Higher dosage of SNF admixture

– (retardation effect-plastic shrinkage)

� Higher cost of concrete!

Hydration Reactions

Glenium Concrete

GLENIUMTM molecules

Improved Dispersion

due to electrostatic and

steric repulsion

….low w/cm

How does Glenium Work?

Glenium Concrete

� Excellent dispersion of binders

� Water reduction upto 40%

� High early strengths

� Reduce/Eliminate SF

� Reasonably lower w/c ratios

� Better Hydration

� Reduction in Cement content

� Lower risk to Thermal Shrinkage

� Faster de-stripping possible

� Economical concrete

� Tolerant to changes in moisture

content

GLENIUM helps in

M 60 Grade at a Site in Chennai

Typical Glenium Mix – M 60

NilNilDepth of water penetration

71.1172.3428 Days

58.258.477 Days

37.4039.463 Days

18.3019.021 Day

0.280.28W/B Ratio

1.2%XXXGlenium Range

xxx1.8%Traditional Admix

161158Water

17221782Total Aggregates

575565Binder

035Silica Fume

15080Flyash

425430Cement

Mix with GleniumMix with SF

Economical Glenium Concrete

160

50

0.08

0.40

30

1.0

4.25

Rs./Kg

37784191Material Cost/Cu.M

11200Glenium Range

0509Trad. Admixture

1311Water


01050Silica fume

15080Flyash

18061828Cement

Mix With GleniumMix with SF

Cost Saving ~ Rs. 400/M3

Glenium Concrete for Lower Grades

Requirements in Lower Grade concrete

� Early age strengths

� Reduction in cement

� Addition of Fly ash

� Lower dosage of admixtures

� Extended retention – 2 to 3 hrs

� Avoid retempering of Concrete

� Tolerance to water (10 – 15 Litres)

Glenium Concrete

� Excellent dispersion of binders

� Water reduction

� lower w/c ratios

� Better Hydration

� Reduction in Cement content

� Early Strength gain

� Addition of Flyash

� Economical concrete

� Tolerant to changes in water content

GLENIUM helps in

Typical Glenium Mix – M 30

38.4035.3228 Days

28.9226.427 Days

18.4016 .233 Days

7.88.301 Day

0.420.46W/B Ratio

0.6%XXXGlenium Range Admixture

xxx1.0%Traditional Admix

152162Water


340340Binder

12060Flyash

220280Cement

Glenium ConcreteTraditional M 30

Economical Glenium Concrete

130

28

0.08

0.40

1.0

4.25

Rs./Kg

20602095Material Cost/Cu.M

2650Glenium Range

095Trad. Admixture

1213Water


12060Flyash

9351190Cement

Mix With GleniumTraditional

Shrinkage Reducing Admixture

TETRAGUARD®

� PLASTIC SHRINKAGE

�� DRYING SHRINKAGEDRYING SHRINKAGE

� THERMAL SHRINKAGE

� AUTOGENOUS SHRINKAGE

� CARBONATION SHRINKAGE

Drying Shrinkage Cracking

Cause:

� Volume reduction due to moisture loss

� Loss of moisture from freshly-hardened concrete

� Loss of moisture from concrete into sub-grade

Joint

Inter-panel Cracking

Drying Shrinkage

Sub-Base

Mechanism of Drying Shrinkage

Capillary Tension appears to be the dominant

mechanism in drying shrinkage. Stress upon

drying is related to the surface tension of pore

water.

Addition of SRA lowers the pore water surface

tension.

How is Surface Tension

Related to Drying Shrinkage?

� Pore water loss due to hydration & evaporation.

� As pores become less

than fully saturated,

meniscus forms at the

air-water interface due

to surface tension.

How is Surface Tension Related to

Drying Shrinkage?

� The surface tension of pore solution that forms meniscus also exerts inward pulling force on the side of the pore wall.

� These forces in all pore sizes ranging from 2.5-50 nm is the primary cause of shrinkage.

Magnitude of Drying Shrinkage

28-Day

� Typically 0.040-0.045%

� Range: 0.025-0.080%

Long-Term

� Typically 0.08%

(800 millionths or 800 microstrains)

� Range: Low: 0.04% High: 0.12%

Shrinkage-Reducing Admixtures

� Developed in 1982 in Japan.

� Function by reducing capillary tension and the tensile forces that develop within the concrete pores as it

dries.

� Primarily used as integral admixtures in concrete mixtures, but some can be applied topically to

concrete surfaces.

TETRAGUARD shrinkage-reducing admixtures

TETRAGUARD AS20 – Liquid form

Offer a practical approach to combat drying shrinkage.

� Dosage: 0.5% - 4.0%, most typical dosage is 1-2%.

Shrinkage-Reducing Admixtures

Designer and Producer Benefits

� Reductions in drying shrinkage, drying shrinkage cracking and

curling.

� Elimination of extra reinforcement needed to restrain expansive forces.

� No special silo or bag storage of Type K cement, expansive aids or aggregates

� No increase in porosity due to microcracking

� Enhanced finishability and truck clean-up

Tetraguard AS 20

A new solution to an old problem:

� Reduced drying shrinkage cracking

� Reduction of curling

-1000

-900

-800

-700

-600

-500

-400

-300

-200

-100

0

0 100 200 300 400 500

Test Age (Days)

µµ µµstrain

Reference SRA

Burbank Water Treatment

Facility, US

Design Considerations and Concerns for

Liquid Containment Structure

�Recommendations from ACI 350 for watertight structures were

specified:

Maximized aggregate size, low w/c of 0.45,

compressive strength of 28 MPa and drying shrinkage

of 0.042% at 28 days.

�Producer also needed pumpable mix with 18±2.5 cm slump for

placement and consolidation around restraint and faced

difficulties in meeting drying shrinkage specification with

aggregates.

Concrete Mixture Proportions

Burbank Water Treatment Facility

Materials Control Mix 2 Mix 3 Mix 4

Type II Cement, kg/m3 383 383 383 383

Sand, kg/m3 761 761 761 761

3/8” Aggregate, kg/m3 197 197 197 197

1” Aggregate, kg/m3 845 845 845 845

Total Water, kg/m3 172 172 172 172

Water/Cement Ratio 0.45 0.45 0.45 0.45

Admixtures

Superplasticizer, g/cwt 142 142 142 142

Air Entrainer, g/cwt 11.3 11.3 11.3 11.3

SRA, l/m3 0.0 2.5 3.7 5.0

Hardened Properties of Burbank Water

Treatment Facility Mixtures

Average Compressive Strength (psi)

Mixture 1-day 3-day 7-day 28-day

Reference 2340 4270 4740 4900

Mixture 2 2640 3770 5210 5860

Mixture 3 2670 4690 5100 6210

Mixture 4 2890 4650 5410 6450

Average Length Change, % (negative sign denotes shrinkage)

Mixture 7-day 14-day 21-day 28-day

Reference -0.023 -0.033 -0.044 -0.049

Mixture 2 -0.011 -0.018 -0.027 -0.034

Mixture 3 -0.009 -0.014 -0.024 -0.028

Mixture 4 -0.007 -0.012 -0.020 -0.023

Comparison Testing of In situ

and Laboratory Specimens

ASTM C157 Shrinkage Data

from Laboratory and Field

Specimens (µµµµstrain)

28-day 115-day 320-day 474-day

Laboratory Average -663 -917 -1003 -1063

Field Average -653 -870 -950 -1023

Reference Specimens

28-day 115-day 320-day 474-day

Laboratory Average -420 -630 -720 -777

Field Average -370 -620 -700 -747

SRA Treated Specimens

ASTM C 157 Shrinkage Data for

Dupont Circle Full Depth Repair

-1200

-1100

-1000

-900

-800

-700

-600

-500

-400

-300

-200

-100

0

100

0 50 100 150 200 250 300 350 400 450 500

Test Age (days)

Length Change ( µµ µµstrain)

Reference - Lab Reference - Field SRA - Lab SRA - Field

In situ Shrinkage Data for

Dupont Circle Full Depth

Repair

-1000

-900

-800

-700

-600

-500

-400

-300

-200

-100

0

0 100 200 300 400 500

Test Age (Days)

µµ µµstrain

Reference SRA

Shrinkage Reduction with SRA

0

10

20

30

40

50

60

28 Days 474 Days

% Drying Shrinkage Reduction

ASTM C157

In situ

Additional Findings

� Enhanced Tensile Bond Strength

� Decreased Volume of Permeable Voids

� TETRGUARD addition did not effect set times

� Addition of TETRAGUARD at reduced restrained drying

shrinkage in adverse simulated desert environments

� Synergy with silica fume

Summary

� SRAs provide significant reductions in drying shrinkage and subsequent cracking in both laboratory and field

investigations.

� Substantial benefits with regards to watertightness, aesthetics and overall serviceability can be obtained

with SRAs.

� Inclusion of SRAs to slabs, bridge decks, liquid containment and repair work can be very advantageous

to improving life cycle.

Production Volume of RMC in Japan (2005)

99.1120,410＜50

100121,550Total

0.91,13050-80

0.01080＜

Composition

Ratio

(%)

Concrete

Volume

(×thousand m3)

Design

Strength

(Mpa/mm2)

Market of Ultra High-Strength

Concrete

A present market

size is not so large.

However, this

technology is

becoming a trend

in Japan.

Why Ultra High-Strength Concrete?

Trend of Architectural Design

1. To get wide-span by downsizing column

2. To get no-column living space for future renewal

3. To improve interior comfort by structural stiffness

Larger Living Space

LargeLarge

SmallSmall SmallSmall

Ultra High-Strength Concrete (UHSC)

Typical Projects

Brillia Tower Tokyo

Place: Kinshi-cho, Tokyo (45F, unit: 644)

Owner: Tokyo Tatemono, completed in 2006

Constructor: TAISEI Corp. Fc130Mpa/mm2

THE KOSUGI TOWER

Place: Kawasaki City, Kanagawa (49F, unit: 689)

Owner: Tokyo Tatemono, completed by June of 2008

Constructor: TAISEI Corp. Fc150Mpa/mm2

Mix Design of UHSC

Materials

Cement: Ordinary Port-land, Low heat, Silica fume premixed

Additive: Silica fume (Powder type, Cement mixed type)

Aggregate: Tight sands, Andesite crashed stone, sands

Admixture: Superplasticizer for Ultra-High-Strength concrete

Existing Product RHEOBUILD SP8HU

Same condition

W/C=15%

Cement paste

Cx5% Cx3%

Fiber: Polypropylene Fiber

Mix Design

Mix Design of UHSC

Strength

(Mpa)

Flow

(cm)

Air

(%)W C 2)

SF Fiber

1 150 65±10 Max.2 SF premixed 15.0 155 1033 (103) 2.5

2 130 65±10 Max.2 SF premixed 18.0 155 862 (86) 2.5

3 60±10 2±1.5 SF premixed 20.0 155 775 (78) 1.0

4 60±10 2±1.5 L + SF 20.0 155 697 78 1.0

5 60±10 2±1.5 SF premixed 30.0 155 517 - 1.0

6 60±10 2±1.5 M, L 25.0 170 680 - 1.0

Remarks1) Type of Cement: L=Low-heat Portland Cement, M=Moderate-heat Portland Cement2) SF: SF=Silica Fume

No.

100

80

Design1) Type of

Cement

W/B

(%)

Unit Weight (kg/m3)

Mix Design of Ultra High-Strength Concrete

Performance Requirements

Performance of Glenium 8008

1. Dispersibility of cement should be higher.

2. Mixing time should be shorter.

3. The viscosity of concrete should be lower.

4. Thixotropy of concrete should be lower.

5. It is necessary to make flowability change

according to time smaller.

Dispersibility of cement


1.0

1.5

2.0

2.5

3.0

3.5

12 14 16 18 20 22 24 26

Existing

Product

Glenium 8008

Water-cement ratio (%)

SP d

osage (C

x%

)

Dispersibility of Glenium 8008 is higher than that of existing product.

Ele

ctric

pow

er consum

ption o

f M

ixer （A

)

90sec

+G

90sec

90sec150sec

+G Discharge Discharge

fasterfaster fasterfaster

Mortal (W+AD+C+S)

Mortal (W+AD+C+S) Mortal +G

Mortal +G

SP8HUSP8HU

GleniumGlenium 80088008Existing Existing

ProductProduct


Mixing Time

Existing Existing

ProductProduct

The improvement

of dispersibility

enables shortening

the manufacturing

time.

Condition of Mix Design

Hardened Property of UHSC

3.767.50.65160LPC51.80.30L30

OP55

LS22

LS18

LS15

LS12

No.

2.543.04.023.30.12

1.868.52.035.70.15

1.870.01.541.90.18

250ml

/B=100k

g

1.2

Dos.

(Bx%)

4.5Slump

19.0

AE water

reducing176OPC47.055.0

2.0

Air

content

(%)

46.6

s/a

(%)

LPC+

SF

Kind

of

binder

68.0

Glenium

8008

150

0.22

Slump

flow

(cm)

Kind of

admix-

ture

Water

(kg/m3)

W/B

(%)

Compressive Strength


0

50

100

150

200

LS22 LS18 LS15 LS12 OP55

1year 6months 91days 56days

28days 7days 1days

Compressive strength(Mpa)

W/C=18% is the

highest MAX:170

Mpa

W/C=18% is the

highest MAX:170

Mpa

Standard Curing

Autogenous Shrinkage


Autogenous shrinkage strain (µ)

Age (day)

-1200-1200-1200-1200

-1000-1000-1000-1000

-800-800-800-800

-600-600-600-600

-400-400-400-400

-200-200-200-200

0000

200200200200

-28-28-28-28 0000 28282828 56565656 84848484 112112112112 140140140140 168168168168 196196196196 224224224224 252252252252 280280280280 308308308308 336336336336 364364364364 392392392392

L30

LS22

LS18

LS15

LS12


Drying Shrinkage

-0.12

-0.10

-0.08

-0.06

-0.04

-0.02

0.00

-10 0 10 20 30 40 50 60

LS12 LS15 LS18

LS22 OP55Length changing ratio (%)

• Drying shrinkage

is remarkably

less than that of

OP55

• The lower the

water-binder

ratio, the lower

the drying

shrinkage

• Drying shrinkage

is remarkably

less than that of

OP55

• The lower the

water-binder

ratio, the lower

the drying

shrinkage

Age (week)

Admixtures for all Situations

� High compressive strength

� Shrinkage Reduction

� Economical Concrete

� Water Tight Concrete

� Extended Haul Concretes

� Speedy Construction

� Impermeable Concrete

� Durable Concrete

Thank You!!

Role of Admixture in Concrete

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