Effect of Novel Organo-Mineral Phases on Cement Hydration and Concrete Properties

L. Raki, J. J. Beaudoin and G. ChanInstitute for Research in Construction, National Research Council Canada

International Summit on Cement Hydration Kinetics and Modeling

Laval University , Quebec, July 27-29, 2009

Outline

• Background

• Controlled release (CR) technology

• Proof of CR concept in concrete

• Application of CR approach in cement/concrete

• Concluding remarks

Depending on the improved property, admixtures can be classified in

different categories:

• Set modifiers: retarders or accelerators

• Water reducers

• Air entraining agents

• Corrosion inhibitors

• Shrinkage reducers

• Pumping aids

• Anti-bleeding, anti-segregation, or anti-washout agents

• Anti-freezing agents

• Defoamers….etc

• Superplasticizers

Sulfonate-based:

• Polymelamine sulfonates (PMF)

• Poly-β-naphthalene sulfonates (PNF)

Carboxylate-based:

• Polycarboxylates

• Polyacrylates

Concrete Admixtures

Rationale for Use of CR Technology

Slump loss:

CR can minimize workability loss and extend the practical range of on-site delivery

Nature of admixtures interactions with cement hydrates influences hardened properties of concrete:

CR can mitigate the effects of preferential adsorption of superplasticizers by aluminate phases

Our Challenge

Develop new technologies and innovative solutions for delivery of

admixtures in cement systems

Use of nanotechnology approach

Synthesis of novel cement-based materials-CR of chemicals

Controlled Release: A Multidisciplinary Concept

• Pharmaceutical: delivery carrier for drugs

• Medicine: gene reservoirs

• Agriculture: plant growth regulators

• Food industry: flavor protection

• Environment: waste treatment

• Construction: cement-additive for time controlled delivery of superplasticizers, corrosion inhibitors and other functional admixtures

“Encapsulation”

• C. M. Dry:

− coated hollow polypropylene fibers used to disperse a corrosion inhibitor (calcium nitrate); Cem. Concr. Res.

28(8),1133, 1998

− Porous aggregate containing antifreeze; Ceram. Trans. v16, 729, 1991

• B. R. Reddy et al. : Oil well treating fluids encapsulated in porous solid materials eg. Metal oxides containing accelerators, retarders, dispersants. US. Patent 6, 209, 646, 2001

Relevant Literature in Cement Systems

Relevant Literature in Cement Systems

“In situ chemical reactions”

K. Hambae et al. : addition of substances which hydrolyze under alkaline conditions (pH=12.5) to form cement dispersing agents. EU Patent EP0402319, 1994; US. Patent 5350450, 1994.

“Intercalation/de-intercalation”

H. Tatematsu et al. : inorganic and organic cation and anion xchangers eg. Calcium substituted zeolite and hydrocalumite. Exchange of alkali and chloride ion inhibit alkali-aggregate reaction and corrosion of rebar. US. Patent 5,435, 848, 1995.

L. Raki et al.: de-intercalation of layered double hydroxides to control loss of workability in cement-based materials, US. Patent Applic. 0022916 A1, 2007

Chemical Structure of Layered (L) Double (D) Hydroxides(Hs)

[ M(II)1-x M(III)x (OH)2 ] [ An-x/n , mH2O ] 2 < 1-x/x < 5

Anions

Approach

CO32- and NO3

-

0.48nm

C= 0.82nm

C=2.18nm

Note:

H2O Molecules have been omitted

2NS

Synthetic Routes and Modification for LDHs

Pillared/Intercalated LDHs derivatives

- High microporosity

- High thermal stability

- Molecular sieve

Calcined LDHs

- High surface area

- Basic properties

- Mixture of oxides

Co-precipitation

- Easy to synthesize

- High charge density

- Poor basic properties

LDH-X

- Halogen scavenger

- Ion exchanger

Memory effect

450 °C 0.1M HX

Ion exchange

Direct/in situ

HydrothermalAnion exchange

XRD Analysis

10 20 30 40 50

2-Theta(°)

0

500

1000

1500

Inten

sity(C

ounts

)

CaAl-LDH

CaAlNBA-LDH

CaAl26NS-LDH

CaAl2NS-LDH

0.86 nm

1.33 nm

1.73 nm

2.18 nm

Raki et al, Cem. Conc. Res, 34(9), 1717-1724, 2004

CaAl2NS-LDH

CaAl2,6NS-LDH

CaAlNBA-LDH

CaAl-LDH

2

SEM Analysis

Inorganic Host: LDH-CaAlOrgano-mineral composite:

CaAl/NBA

10 20 30 40

2-Theta(°)

0

50

100

150

200

250

300

350

400

450

500

Inte

nsity(C

ounts

)

C2ANBA

Deint15

Deint30

Deint120

Deint180

De-intercalation (0.1M NaOH)

Admixture DeliveryNitrobenzoic Acid (NBA)

2

10 20 30 40

2-Theta(°)

0

250

500

750

Inte

nsity(C

ounts

)

C2ANBA

Deint15

Deint30

Deint120

Deint180

De-intercalation (0.2M NaOH)

Admixture DeliveryNitrobenzoic Acid (NBA)

0

0.5

1

1.5

2

2.5

3

0 5 10 15 20 25 30

Time in Hours

Heat

Ou

tpu

t

Control

Control +0.06 g Composite

Control + 0.06 g Accelerator (NBA)

Control + 0.24 g Composite

Control + 0.24 g Accelerator (NBA)

Conduction Calorimetry

C3 S (w/s=0.50)

Other Organic Species

• 2 Naphtalene sulfonate (2NS)

• 2, 6 Naphtalene sulphonate (26NS)

• Polyacrylique acid (PAA)

• Polyvinyl Alcohol (PVA)

• Dicarboxylate

• Polycarboxylate

• Disal

Different types of interactions: full/partial intercalation, adsorption, exfoliation

Hydration at 28 days

10 20 30 40 50

2-Theta(°)

0

250

500

750

1000

Inte

nsity(C

ounts

)

OPC

OPC Disal 0.3%

OPCCaDisal 2.4%

Mortar Cubes

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

0 5 10 15 20 25 30

Co

mp

res

siv

e s

tren

gth

, M

Pa

Time, days

Compressive strength of mortar cube

OPC Control

0.3% Ca-Al

0.6% Ca-Al

0.3% Disal

0.6% Disal

2.4% Ca-Al_Disal

OPC OPC Disal

OPC CaDisal

• LDH-based composites have the potential to provide improved controlled release of chemical admixtures in cement-based materials

• Application of LDH-based CR technologies are versatile with the potential to use different processes and a variety of admixtures

• Controlled release of all types of superplasticizers in concrete is a promising developing technology

Concluding Remarks

www.irc.nrc-cnrc.gc.ca