New Advanced Admixtures for UHPC · New Advanced Admixtures for UHPC Vietnam Concrete Association...

New Advanced Admixtures

for UHPC

Vietnam Concrete Association (VCA)

Hanoi, 13 March 2019

Prof. Dr. Johann Plank

Chair for Construction Chemicals

Technische Universität München, Germany

Introduction of Munich and TUM

© Prof. Plank 2019

1995 - Ultra-High Strength Concrete

Microsilica

Dense particle packing in UHPC

w/c ratio < 0.25 !

© Prof. Plank 2019

UHPC can reach 200 MPa compressive strength !

Iconic Buildings

Singapore, Marina Bay Sands Casino

© Prof. Plank 2019

Kingdom Tower, Jeddah, Saudi-Arabia, 1007 m,

built by Saudi Bin Ladin Group

Viewing platform at 800 m

Iconic Buildings Using Hi-Tech Concrete

© Prof. Plank 2019

Content …..

….. PCEs – the basis for UHPC

….. Admixtures for fast flowing concrete

….. Non-adsorbing flow enhancers

….. Phosphate ester superplasticizers

….. Early strength

enhancing admixtures

….. Conclusion

1981 – Invention of Polycarboxylates (PCEs)

CH2 C

CH3

C

ONa

O

CH2 C

CH3

C

O

CH2

CH2

O

CH3

O

a b

n

Methacrylic acid – MPEG Methacrylate ester copolymer

Nippon Shokubai, 1981

Dr. Tsuyoshi Hirata

© Prof. Plank 2019

PAAM PCE

Sika / Toho 2000

MPEG PCE

Nippon Shokubai 1981

VPEG PCE

BASF 1995

APEG PCE

Nippon Oil & Fats 1989

Development of PCE Technology

© Prof. Plank 2019

Development of PCE Technology

X PCE

China, ~ 2004

HPEG PCE

China, 2000

b

IPEG PCE

Nippon Shokubai 1998

© Prof. Plank 2019

Different Molecular Conformations of PCEs

(1) MPEG

(2) APEG

(3) VPEG

(4) PAAM PCE

(5) HPEG

(6) IPEG

(7) X PCE

© Prof. Plank 2019

Microstructure of PCEs

-

--- -- ---- ----- -- - --- -- ----- ----- -- - -

--- -- ---- ----- -- - --- -- ----- ----- -- -

gradient polymerRegular (statistical) copolymer

© Prof. Plank 2019

PCE Structures For Precast and Ready-Mix Concrete

© Prof. Plank 2019

Precast concrete PCE:

• High anionic character

• Long side chain

Ready-mix concrete PCE:

• Low anionic character

• Short side chain

Examples of Commercial PCEs

Used in Precast Concrete

© Prof. Plank 2019

MPEG-PCE HPEG-PCE

PCE Effectiveness and Time of Addition

© Prof. Plank 2019

➢ Generally, superplasticizers should be added to concrete

as late as possible

➢ Delayed addition can save up to 50 % in dosage

PCEs can introduce significant amounts of air into concrete

© Prof. Plank 2017

Foam of beer

American beer –

unstable foam

German beer –

stable foam

PCEs Introduce Foam into Concrete

Defoaming of PCE Concrete

© Prof. Plank 2019

PCEs always require a defoamer !

A. Jeknavorian,

“Overview of Defoamer Technologies for Polycarboxylates”, in: J. Plank, L. Lei (eds.), workshop on PCE Technology,

27 September 2017, Munich, Germany.

Problems associated with defoamers:

• Must not separate from PCE solution

• Shelf life over at least 1 year required

• Different PCEs need different defoamers

• Defoamers for short and long-term effect

• PCE solutions typically contain mixture

of defoamers

Jeffox WL5000

Mild defoamer, easy to disperse

Jeffamine M2005

Strong defoamer, stable ion-pair with PCE

Tributylphosphate

Moderate defoamer, requires emulsion

Working Mechanism of Defoamers

© Prof. Plank 2019

Spriting effect of defoamers on foam lamella

a defoamer spreads on the surface of the foam lamella (= spriting)

and pushes the surfactant molecules away

the foam lamella becomes unstable and releases the air

defoamer

Content …..







….. Conclusion

Importance of Flow Behavior of Concrete

© Prof. Plank 2019

viscous concreteconcrete with

superplasticizer

PCEs Decrease the Size of Ettringite Crystals

Ettringite, precipitated in

absence of PCE

PCEs can modulate the crystal size of ettringite

Ettringite, precipitated in

presence of MPEG-PCE

5 μm 200 nm

© Prof. Plank 2019

Cement Compatibility of PCEs

Size of ettringite crystals, formed in the presence of

different PCEs

MPEG-PCEs: very small crystals, incompatible with this cement

APEG-PCEs: medium crystal size, moderately compatible

IPEG-PCEs: large crystals, very compatible

PCE Polymer

Size of ettringite crystals[nm]

HLB ValueCompatibility with“difficult” cements

MPEG-7 718 ± 14 16.4 incompatible

MPEG-45 981 ± 24 18.2 incompatible

APEG-23 1,238 ± 27 19.3 medium

IPEG 50 1,936 ± 86 18.6 compatible

APEG-34OH 2,050 ± 65 19.7 compatible

Referenz

ohne PCE~ 5,000 ± 300 - -

© Prof. Plank 2019

Effect of MPEG-PCE on Size of Ettringite

Preparation of synthetic ettringite from Ca(OH)2/Al2(SO4)3

solutions in presence of PCE

© Prof. Plank 2019

Content …..

….. PCE – the basis for UHPC

….. Admixtures for fast-flowing concrete





….. Conclusion

Courtesy of Paul Bowen,

EPFL Lausanne

Molecular simulation of the adsorption

of polyacrylic acid (10 monomer units)

on (104) surface of calcite

(water molecules not shown here)

The Process of Adsorption of PCE

ΔGads = ΔHads - TΔSads

Plank J., B. Sachsenhauser, J. de Reese

"Experimental determination of the thermodynamic parameters affecting the adsorption

behaviour and dispersion effectiveness of PCE superplasticizers",

Cement and Concrete Research 2010, 40, 699 – 709.

© Prof. Plank 2019

Fluidizing Effect of Non-Adsorbing Polymers

Highly important in low w/c concrete like UHPC

© Prof. Plank 2019

Dependence of Effect on w/c Ratio

Effect much more pronounced at w/c = 0.22

Jeffamine® more effective than DEG

© Prof. Plank 2019

Content …..





…... Early strength


…… Conclusion

Phos – PCE Via Free Radical Copolymerization

• Phos-PCEs perform better than pure phosphated comb polymers

• very robust in presence of other admixtures (no desorption)

• work well in blended cements

• Patents from Kao / Japan

© Prof. Plank 2019

Phos – SP Via Polycondensation

• highly effective in cement and gypsum

• works very well also at low w/c ratios (< 0.30)

• provides high flow speed to concrete

• technology of BASF

phenol

© Prof. Plank 2019

Polyphosphate Superplasticizer

Dispersing performance

in cement

Dispersing performance

in CaSO4 hemihydrate

© Prof. Plank 2019

Content …..







….. Conclusion

© Prof. Plank 2019

Strength Development From Clinker Phases

C3S responsible for early strength of concrete:

© Prof. Plank 2019

The Difference Between C3S and C2S

Ca3(SiO4)O (triclinic) Ca2(SiO4)

C3S is tricalcium oxy silicate

O2-

Admixtures For High Early Strength

© Prof. Plank 2019

Alkaline accelerators

Na2SiO3, NaAl(OH)4

Alkali-free accelerators

Al(OH)SO4, Al(OH)2(HCOO),

Al(OH)3 amorphous

Conventional accelerators

Ca(NO3)2, Ca(HCOO)2

Disadvantage: they all reduce final strength !

C-S-H Foils as Nuclei for C-S-H Needles

© Prof. Plank 2019

C-S-H needlesC-S-H foils

1. I.G. Richardson, The calcium silicate hydrates, Cement and Concrete Research, 38 2008, 137-158.

2. E.T. Rodriguez, I.G. Richardson, L. Black, E. Boehm-Courjault, A. Nonat, J. Skibsted,

Composition, silicate anion structure and morphology of calcium silicate hydrates (C-S-H) synthesized by silica-lime

reaction and by controlled hydration of tricalcium silicate, Advances in Applied Ceramics, 114, 2015, 362-371.

Seeding Effect of C-S-H-PCE Nanocomposites

• C-S-H seed crystals accelerate C-S-H formation

Na2SiO3 + Ca(NO3)2 C-S-H - PCEPCE

Thin foils, dispersed by PCE

Preparation of Nano C-S-H Seed Crystals using PCE :

Source: BASF

© Prof. Plank 2019

Early Strength Enhancement with C-S-H-PCE

• Nanofoils of C-S-H - PCE composite produce significantly

higher early strengths

500 nm

TEM image of C-S-H – PCE

nanocomposite

Mortar testing according to DIN EN 196-1

after 6 and 10 h; CEM I 52.5 R, w/c = 0.5

© Prof. Plank 2019

50 nm

50 nm50 nm

Metamorphosis of C-S-H – PCE

4 h4,5 h

4 h

© Prof. Plank 2019

Nanofoils form inside the metastable C-S-H droplets

Recrystallisation of C-S-H

50 nm

Foils

Foils

2 h

50 nm

5 h

2 h

50 nm PCE shell

Acceleration of CEM II /B-V by C-S-H – PCE

Earlier consumption of Portlandite (Ca(OH)2) signifies

that pozzolanic reaction starts earlier

OPC Clinker + 35 % fly ash + 2,0 % C-S-H – PCE:

Portlandite reflection

Kanchanason V., Plank J.,

"Effectiveness of a calcium silicate hydrate – Polycarboxylate ether (C-S-H-PCE) nanocomposite on early strength

development of fly ash cement",

Construction and Building Materials 169 (2018) 20 – 27.

Acceleration of CEM II /B-S by C-S-H – PCE

© Prof. Plank 2019

OPC Clinker + 35 % Slag + 2,0 % C-S-H – PCE:

Portlandite

Hemicarbonate

Strength exceeding

that of OPC !

Acceleration of CEM II /B-V by C-S-H – PCE

© Prof. Plank 2019

OPC Clinker + 35 % Calcined clay + 2.0 % C-S-H – PCE:

Portlandite

Hc

Hemicarbonate

Strength exceeding

that of OPC !

C-S-H-PCE Accelerator Improves Durability of Concrete

© Prof. Plank 2019

normally, C-S-H crystallizes only on the surface of cement particles

C-S-H - PCE initiates C-S-H crystallization also in the pore solution

between cement particles

decreased porosity and permeability increase durability

→ more ecological concrete !

Valentini L., Ferrari G., Russo V., Stefancic, M., Serjun V.Z., Artioli G.,

„Use of nanocomposites as permeability reducing admixtures“,

Journal of the American Ceramic Society 101(2018) 4276.- 4284.

Content …..







….. Conclusion

Low Ductility – The Main Problem of Modern Concrete !

C-S-H phases in concrete

US warship from WW II made from LWAE concrete

The tensile strength of

concrete is too low !

Concrete has poor

fracture toughness and

no ductility

© Prof. Plank 2019

Improvement of Concrete Microstructure

Brittleness of concrete: very low tensile (bending) strength

Ratio between compressive & tensile strength is too high!

Calcite

Hydroxyapatite

Skin

100

10

1

0.1

0.01

0.001

0.0001

0.001 0.01 0.1 1 10 100 1000

To

ug

hn

es

s,

J (

kJ m

)

-2c

Cork

Keratin

Bone

Wood (fibrous mode)

Wood (splitting mode)

Mollusk shell

Enamel

Dentine

Natural elastomers

Natural polymers, polymer

composites

Natural ceramics, ceramic

composites

Modulus, E (G a)PModified after Dunlop and Fratzl (2010). Annu. Rev. Mater. Res. , 40, 1 -24.

For comparison:

(stiffness 300 GPa, strength 4 GPa, toughness 25 MJ m ) (stiffness 200 GPa, strength 1.5 GPa, toughness 6 MJ m )

(Meyers et al. 2008. Progress in Mat. Sci., 53, 1-206)

Carbon fibreHigh-tensile steel

-3

-3

Concrete

UHPC

Concrete

Bone

© Prof. Plank 2019

Importance of Construction Acitivity

© Prof. Plank 2019

o Germany has highest growth rate in Europe

o Reason: larger construction activity

Expanding highwaysConstruction of homes and appartments

Global Superplasticizer Market

© Prof. Plank 2019

Worldwide volume: ~ 4.5 mio tons 40 % liquid

In Germany PCE is used much more than BNS, MFS

Total PCE produced in China:

~ 2.2 mio tons

Top 10 PCE producers in China:

~ 1.2 mio tons

Largest PCE producer in China:

~ 300.000 tons

BNS, MFS

PCE

Total SuperplasticizerGermany

Educational Courses in Building Materials

TUM Singapore

New Advanced Admixtures for UHPC · New Advanced Admixtures for UHPC Vietnam Concrete Association...

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