Role Of Admixture In Concrete

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ROLE OF ADMIXTURES IN READYMIX CONCRETE

Contents 1

INTRODUCTION

2 GLENIUM CONCRETE 3 SHRINKAGE REDUCING CONCRETE 4 ULTRA HIGH STRENGTH CONCRETE 5 CONCLUSION

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

Slump flow [cm]

Main effect of plasticizing admixtures

1

with Plasticizer 2

without Plasticizer Water/Cement Ratio

1

Higher workability at constant w/c ratio

2

Increase of strength parameters through reduction of w/c ratio at constant slump flow

Types of concrete admixtures 

Lignosulphonates – LS



Beta-Naphthalenesulphonate - Polycondensate – BNS



Melamine-Sulphonate-Poly-condensate – MFS



Poly Acrylates – PAC



Polycarboxylate Ethers - PCE

Traditional Plasticizers/Superplasticizers Mode of Action

Electrostatic Repulsion

BNS molecules

Mode of Action

1. Step: surface charges ( positive zeta potential) -O

cement grain

-O -O

O-

Ca2+ Ca2+

Ca2+

Ca2+

Ca2+

O-

Ca2+ Ca2+

Ca2+ Ca2+

-O

Ca2+

Ca2+

O-

Ca2+

Ca2+

Ca2+

Ca2+ Ca2+

Ca2+

Ca2+

Ca2+

O-

Ca2+

-O

Ca2+

Ca2+

formationCa Ca of positively charged Ca Ca Ca Ca Ca surfaces Ca

Ca2+

O-

2+

2+

2+

-O

2+

2+

2+

-O -O

O-

2+

2+

Ca2+ Ca2+ Ca2+ Ca2+

Ca2+

Ca2+

Ca2+

O-

Ca2+

Ca2+

O-

Ca2+

-O

Ca2+

Ca2+

Ca2+ Ca2+

OCa2+

Ca2+

-O

Ca2+

Ca2+

Ca2+

Ca2+

O-

cement grain

Ca2+

Mode of Action nd

step: adsorption of dispersants negatively functional negativelycharged charged functionalgroups groups 2+  Ca Oprovide providewater watersolubility solubilityand andaffinity affinityto to positively charged surfaces 2+ positively charged surfaces 

O-

Ca

Ca -O  -OCa

2+

2+ 2+  Ca

O-

Ca2+ -O

st nd addition OCa additionof of11stor or22ndgeneration generation (super-)plasticizers O(super-)plasticizers Ca 2+

 -OCa

2+

2+

OCa e.g. e.g.lignin ligninsulfonates, sulfonates, naphthalene-sulfonatenaphthalene-sulfonate Ca O-O Ca formaldehyde formaldehyderesins resins Ca melamine-formaldehyde-sulfonate -O melamine-formaldehyde-sulfonate OCa resins resins OCa  Ca -O 2+

Ca2+ -O 2+

2+

2+

2+

2+

Ca -O

2+

2+

2+ Ca

O-

cement grain

2+

 -OCa

cement grain

2

Mode of Action th

4 step: loss of workability over time 2+ Ca

O-

2+

Loss Lossof ofdispersing dispersingeffect! effect!

cement grain

 2+ Ca

-O  -OCa

2+  Ca

O-

2+ 2+  Ca

O-

-O

Ca2+ 

2+ Ca

-O

Ca2+

OOCa 2+

 2+ Ca

O-

Ca2+ -O

 -OCa

2+

2+  Ca

O-

 -OCa

2+

 2+ Ca

-O

 -OCa

2+

2+ Ca

Incorporation Incorporationof ofsuperplasticizers superplasticizers into intogrowing growinghydrate hydratephases phases

O-

 2+ Ca

O-

2+ Ca

O-

cement grain

 -OCa

Volume of Admixtures

Innovation History of Water Reducer Technology

AE high water-reducing agent Super plasticizer [Glenium] Conventional AE waterreducing agent [Pozzolith] High water-reducing agent [Rheobuild]

1950

1960

1970

1980 Year

1990

2000

2010

PCE Molecule 

  

complex and flexible molecules, comprising of main chain Side chains functional groups.

PCE Based - GLENIUM Molecules

Electrostatic and Steric Repulsion GLENIUM molecules

Mode of Action

 -OCa  -OCa

cement grain

2+ 2+

2+ 2+

Introduction Introductionof of side sidechains chains

2+ 2+   Ca Ca

O-

2+ 2+   Ca Ca

O-

2+ 2+   Ca Ca

O-

2+ Ca2+

-O

2+ 2+   Ca Ca

-O

2+ Ca2+

2+ Ca2+ -O

 -OCa

2+ 2+

 -OCa

2+ 2+

  2+ 2+ Ca Ca

O-

2+ 2+   Ca Ca

O-

O-

2+ 2+

2+ 2+

polyether carboxylates Coulomb Coulomb Coulomb andonly! steric repulsion repulsion only! repulsion

2+ 2+

2+ 2+   Ca Ca

 -OCa  -OCa

st st generation: 1 21nd generation: generation:

O OCa Ca

more effective!

 2+  2+ Ca Ca

O-

 2+  2+ Ca Ca

O-

cement grain

2+ 2+

 -OCa

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



Constraint – Shrinkage, which is sensitive to use of higher cement content & SF

Large pours to be done Voids & honeycombs cannot be tolerated

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

How does Glenium Work?

GLENIUMTM molecules

Improved Dispersion due to electrostatic and steric repulsion ….low w/cm

Glenium Concrete GLENIUM helps in

 Excellent dispersion of binders  Better Hydration  Water reduction upto 40%  Reduction in Cement content  Lower risk to Thermal Shrinkage  High early strengths  Reduce/Eliminate SF  Reasonably lower w/c ratios

 Faster de-stripping possible  Economical concrete  Tolerant to changes in moisture content

M 60 Grade at a Site in Chennai

Typical Glenium Mix – M 60 Mix with SF

Mix with Glenium

Cement

430

425

Flyash

80

150

Silica Fume

35

0

565

575

Total Aggregates

1782

1722

Water

158

161

Traditional Admix

1.8%

xxx

Glenium Range

XXX

1.2%

W/B Ratio

0.28

0.28

1 Day

19.02

18.30

3 Days

39.46

37.40

7 Days

58.47

58.2

28 Days

72.34

71.11

Nil

Nil

Binder

Depth of water penetration

Economical Glenium Concrete Rs./Kg

Mix with SF

Mix With Glenium

Cement

4.25

1828

1806

Flyash

1.0

80

150

Silica fume

30

1050

0

Total Aggregates

0.40

713

689

Water

0.08

11

13

Trad. Admixture

50

509

0

Glenium Range

160

0

1120

4191

3778

Material Cost/Cu.M

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 GLENIUM helps in

 Excellent dispersion of binders  Better Hydration  Reduction in Cement content  Water reduction

 Early Strength gain  Addition of Flyash

 lower w/c ratios

 Economical concrete  Tolerant to changes in water content

Typical Glenium Mix – M 30 Traditional M 30

Glenium Concrete

Cement

280

220

Flyash

60

120

340

340

Total Aggregates

1842

1820

Water

162

152

Traditional Admix

1.0%

xxx

Glenium Range Admixture

XXX

0.6%

W/B Ratio

0.46

0.42

1 Day

8.30

7.8

3 Days

16 .23

18.40

7 Days

26.42

28.92

28 Days

35.32

38.40

Binder

Economical Glenium Concrete Rs./Kg

Traditional

Mix With Glenium

Cement

4.25

1190

935

Flyash

1.0

60

120

Total Aggregates

0.40

737

728

Water

0.08

13

12

Trad. Admixture

28

95

0

Glenium Range

130

0

265

2095

2060

Material Cost/Cu.M

Shrinkage Reducing Admixture

TETRAGUARD®     

PLASTIC SHRINKAGE DRYING 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

Drying Shrinkage

Sub-Base Inter-panel Cracking

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.



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

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

Shrinkage-Reducing Admixtures 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%.

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

0 -100 -200

 Reduction of curling

µ strain

-300 -400 -500 -600 -700 -800 -900 -1000 0

100

200

300

400

Test Age (Days)

Reference

SRA

500

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 Sand, kg/m3 3/8” Aggregate, kg/m3 1” Aggregate, kg/m3 Total Water, kg/m3 Water/Cement Ratio

383 761 197 845 172 0.45

383 761 197 845 172 0.45

383 761 197 845 172 0.45

383 761 197 845 172 0.45

Admixtures Superplasticizer, g/cwt Air Entrainer, g/cwt SRA, l/m3

142 11.3 0.0

142 11.3 2.5

142 11.3 3.7

142 11.3 5.0

Hardened Properties of Burbank Water Treatment Facility Mixtures

Mixture Reference Mixture 2 Mixture 3 Mixture 4

Average Compressive Strength (psi) 1-day 3-day 7-day 2340 4270 4740 2640 3770 5210 2670 4690 5100 2890 4650 5410

28-day 4900 5860 6210 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 (µ µstrain) Reference Specimens Laboratory Average Field Average

28-day -663 -653

115-day -917 -870

320-day -1003 -950

474-day -1063 -1023

SRA Treated Specimens Laboratory Average Field Average

28-day -420 -370

115-day -630 -620

320-day -720 -700

474-day -777 -747

ASTM C 157 Shrinkage Data for Dupont Circle Full Depth Repair

L ength C hange (µ strain)

100 0 -100 -200 -300 -400 -500 -600 -700 -800 -900 -1000 -1100 -1200 0

50

100

150

200

250

300

350

400

450

500

Test Age (days)

Reference - Lab

Reference - Field

SRA - Lab

SRA - Field

In situ Shrinkage Data for Dupont Circle Full Depth Repair 0 -100 -200

µ strain

-300 -400 -500 -600 -700 -800 -900 -1000 0

100

200

300

400

Test Age (Days)

Reference

SRA

500

Shrinkage Reduction with SRA 60

ASTM C157 In situ

% Drying Shrinkage Reduction

50

40

30

20

10

0 28 Days

474 Days

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.

Market of Ultra High-Strength Concrete Production Volume of RMC in Japan (2005)

Design Strength (Mpa/mm2)

Concrete Volume (×thousand m3)

Composition Ratio (%)

80<

10

0.0

50-80

1,130

0.9

<50

120,410

99.1

Total

121,550

100

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

Small

Small

Large

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

Fiber:

Polypropylene Fiber Cx5%

Cx3% Same condition W/C=15% Cement paste

Existing Product

RHEOBUILD SP8HU

Mix Design of UHSC Mix Design

Mix Design of Ultra High-Strength Concrete

Design No.

1)

Type of Cement

W/B (%)

W

C

Max.2

SF premixed

15.0

155

1033

(103)

2.5

65±10

Max.2

SF premixed

18.0

155

862

(86)

2.5

60±10

2±1.5

SF premixed

20.0

155

775

(78)

1.0

60±10

2±1.5

L + SF

20.0

155

697

78

1.0

60±10

2±1.5

SF premixed

30.0

155

517

-

1.0

60±10

2±1.5

M, L

25.0

170

680

-

1.0

Strength (Mpa)

Flow (cm)

Air (%)

1

150

65±10

2

130

3

100

4 5 6

80

Unit Weight (kg/m3)

Remarks 1) Type of Cement: L=Low-heat Portland Cement, M=Moderate-heat Portland Cement 2) SF: SF=Silica Fume

2)

SF

Fiber

Performance of Glenium 8008 Performance Requirements

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.

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

SP dosage (Cx%)

3.5 3.0

Existing Product

2.5 2.0 1.5

Glenium 8008

1.0 12

14

16

18

20

22

24

Water-cement ratio (%)

26

Performance of Glenium 8008 Electric power consumption of Mixer (A)

Mixing Time

Existing Product SP8HU

+G Glenium 8008

+G

Discharge

Discharge

Existing Product

The improvement of dispersibility enables shortening the manufacturing time.

faster Mortal (W+AD+C+S)

Mortal +G

90sec

150sec Mortal (W+AD+C+S)

90sec

faster

Mortal +G

90sec

Hardened Property of UHSC Condition of Mix Design

Kind of binder

W/B

s/a

(%)

(%)

LS12

0.12

23.3

LS15

0.15

35.7

LPC+ SF

No.

LS18

0.18

41.9

LS22

0.22

46.6

L30

0.30

51.8

OP55

55.0

47.0

LPC OPC

Water (kg/m3)

150

Kind of admixture

Glenium 8008

160 176

AE water reducing

Air

Slump flow

content

(cm)

(%)

4.0

43.0

2.5

2.0

68.5

1.8

1.5

70.0

1.8

1.2

68.0

2.0

0.65

67.5

3.7

Dos. (Bx%)

250ml /B=100k g

Slump 19.0

4.5

Hardened Property of UHSC Compressive Strength Standard Curing Compressive strength (Mpa)

200

1year 28days

6months 7days

91days 1days

W/C=18% W/C=18%isisthe the highest highestMAX:170 MAX:170 56days Mpa Mpa

150

100

50

0 LS22

LS18

LS15

LS12

OP55

Hardened Property of UHSC Autogenous Shrinkage Age (day) Autogenous shrinkage strain (µ)

-28 0

28 56 84 112 140 168 196 224 252 280 308 336 364 392

200 0

L30

-200

LS18

-400 -600 -800 -1000 -1200

LS15

LS22

LS12

Hardened Property of UHSC Drying Shrinkage Age (week) Length changing ratio (%)

-10

0

10

20

30

40

0.00

-0.04

•• The The lower lower the the water-binder water-binder ratio, ratio, the the lower lower the the drying drying shrinkage shrinkage

-0.06 -0.08

-0.12

60

•• Drying Drying shrinkage shrinkage is is remarkably remarkably less less than than that that of of OP55 OP55

-0.02

-0.10

50

LS12

LS15

LS22

OP55

LS18

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!!

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