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WATER RESISTING ADDITIVES FOR CEMENT BASED BUILDING MATERIALS BY USING SILICONE TECHNOLOGIES 3.NOVEMBER 2016 MARKUS ROOS

CALUCEM DAYS - EVONIK NUTRITION & CARE GMBH

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AGENDA

•  Basics

•  Silicone Chemistry

•  Test Results

DAMAGE MECHANISM: I. WATER UPTAKE DUE TO CAPILLARY ACTION

Water

bigger pore

Smaller pore

Water transport in pores due to capillary action

Capillary action occurs if the adhesion of water to the walls is stronger than the cohesive forces between the liquid molecules.

The smaller the pore diameter the higher is the capillary pressure to raise water.

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Efflorescence The optical function of concrete elements can be affected by efflorescence.

Primary Efflorescence

The calcium hydroxide Ca(OH)2 of young concrete can react with carbon dioxide CO2 from the air. The result is a whitish efflorescence of calcium carbonate CaCO3 on the young concrete surface.

Secondary Efflorescence

Minerals solved in water are transported to the surface. If the water evaporates the salts will remain on the top.

Crystallisation pressure

By reversibly absorbing crystallization water the volume of certain salts increases. This crystallization pressures cause structural cracks.

Damage mechanism II. Efflorescence

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Na2SO4 +10 H2O + < 32,7°C >>> Na2SO4 . H2O

DAMAGE MECHANISM: III. FREEZE / THAW DAMAGE

Water freezes to ice

Volume increase by almost 10% Destroyed cement based joints

due to freeze deicing damage

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DAMAGE MECHANISM: IV. REBAR CORROSION

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AGENDA

•  Basics

•  Silicone Chemistry

•  Test Results

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SILICONES

Benefits

physiologically indifferent

high chemical stability

low surface tension

liquid in a broad field of temperature

good gliding properties

good spreadability

hydrophobic

high temperature stability

M D D‘ M

R

Low surface tension to avoid water uptake

TEGOSIVIN

Water and dissolved pollutions are repelled by a TEGOSIVIN

treatment

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High Surface Tension e.g. pure water (72 mN/m)

Low Surface Tension

Surface Tension is responsible for the shape of liquid droplets

MAJOR USED SILICONES AS WATER REPELLENTS

Silanes Siloxanes Silicone Resins

•  monomeric molecules

•  low molecular weight

•  alkoxyfunctional

•  high VOC

•  Octyl-/iso-octyl-/isobutyl

•  alkyl chain-length provides steric protection

•  excellent impregnation depths specifically in alkaline substrates ( concrete )

•  oligomeric or polymeric molecules

•  alkoxyfunctional

•  organo-modified siloxanes

•  low VOC

•  good beading performance

•  can be used in low solid formulation

•  mainly used for hydrophobisation of neutral and natural substrates

•  highly branched polysiloxanes of higher molecular weight

•  less penetration depth

•  low alkaline stability

•  provide excellent beading properties

•  Only used in coatings

R R

OR

RO

RO

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SILANE STRUCTURES –

FUNCTIONALITY

Short Length of Alkyl chain - Hydrophobic Groups Long

H

C H H

Si

R—

O

Methyltriethoxysilane [MTEOS]

CH3

CH2 CH2

CH2 CH2

CH2 CH2

CH2

Si

R—

O

n-Octyltriethoxysilane [n-OCTEO]

Reactive Alkoxy Groups - Bonding

Stronger Water Repellency Weaker

Methyl (CH3) Octyl (C8H17)

Weaker Alkali resistance by steric hinderance Stronger

Short Length of Alkyl chain – Bonding Groups Long

Little Mobility Better

Methoxy (OCH3) Ethoxy (OC2H5)

Faster Reaction speed Slower

Alkyl Groups Water Repellency

SILICONE WATER REPELLENTS

PRODUCT CLASSES

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Con

cent

rate

s fo

r sol

vent

bor

n sy

stem

s

• 100% actives

• Diluent: white spirit

• Ready for use concentation 5-100%

• For the use on very dense substrates

• Silanes mainly for concrete protection

• Siloxanes for neutral and natural substrates only

Con

cent

rate

s fo

r wat

er b

orn

syst

ems • 40-60 % actives

• Diluent water

• Ready for use concentation 5-40%

• For the use on variety of substrates

• Silanes mainly for concrete protection

• Siloxane/Siloxane blends for neutral and natural substrates only

• For the use as an admixture into concrete

Past

y sy

stem

s re

ady

for u

se

• 25 -80% actives

• Ready to use –no dilution is needed

• High active cremes are for special applications like DPC and concrete protection

• Low actives cremes for fassade application

Pow

dere

d pr

oduc

ts

• 20-100% actives

• Ready for use

• Just for drymix mortar applications

• Preblended into mortars

Water Repellency and Efflorescence Control Our high performance water repellents provide durable protection against water by Silane and

Siloxane technologies. They are highly efficient hydrophobizing agents for concrete and dry-mix

applications:

Drymix Mortars

Renders Repair Mortars Technical Mortars Flooring Products Tile Adhesives Grouts Joint Fillers

APPLICATION FIELDS

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Semi Dry Concrete

•  Pigmented Concrete •  Concrete pavers

Wet Concrete

•  Prefab concrete •  Concrete tubes •  Concrete curbs •  Transport concrete •  Water proofing concrete

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AGENDA

•  Basics

•  Silicone Chemistry

•  Test Results

ADMIXTURE PREPARATION

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Powdered Admixture Blend all the dry components for 2 minutes with a Mixer at low shearing speed. Add the water to the dry blend and keep on stirring for 1 Minute. Fill the mortar into forms and compress it with a vibrator table for 45 sec. Seal the form with a cover and store it for 2 days at room temperature. Remove the concrete from the form and store it for additional 26 days at room temperature before you make the water absorption tests. Liquid Admixture Blend the admixture with the water at first. Add the water/Admix blend to the dry blend and keep on stirring for 1 Minute. Fill the mortar into forms and compress it with a vibrator table for 45 sec. Seal the form with a cover and store it for 2 days at room temperature. Remove the concrete from the form and store it for additional 26 days at room temperature before you make the water absorption tests.

CAPILLARY WATER UPTAKE

ACC. TO EN ISO 15148

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After impregnation and airing, the test specimens are, as described above, stored on a soft foam saturated with polyurethane ether. Due to their own weight, the specimens press water out of the foam, so that constant contact of the contact surface is ensured. By weighing after 1h, 4h, 9h, and 25h, the water uptake in g/m² is monitored. Before each weighing, any water adhering to the surface is blotted with an absorbent paper towel. The reduction of water uptake should be > 70 % relative to the blank value.

SILANE/SILOXANE BASED WATER REPELLENTS

FOR DURABLE PROTECTION

Capillary water uptake of treated tile grouts over repeated test cycles

0

50

100

150

200

250

300

350

0 10 min. 20 min. 30 min. 60 min. 4 h 6 h 24 h 48 h 72 h

mg/

cm²

Time

Control 1st cycle Metalsoaps 4th cycle, Metalsoaps

1st cycle, Sitren P 750 4th cycle, Sitren P 750

Stearates: Loss of Protection

Siloxane/Silane: permanent

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0

1

2

3

4

5

6

0 1 H 5 H 8 H 24 H 48 H

WAT

ER A

BSO

RPT

ION

(%)

TIME (HOURS)

Blank 0.1% - P 750 0.2% - P 750 0.3% - P 750 0.4% - P 750 0.5% - P 750

SITREN® P 750 IS HIGHLY EFFICIENT AT REDUCING WATER ABSORPTION THROUGH CAPILLARY UPTAKE

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Mixing Design Cement I 42,5 R 900 g Sand < 2 mm 2700 g Water repellent 0,9 g Pigment 7,2 g Water 360 g

SALT BLOOMING RESULTS

- SECONDARY EFFLORESCENCE

Control Metal Soap Siloxane / Silane

Determination of the salt blooming according DIN 52111

The hardened concrete (28d) is placed partially (approx. 1 cm) in a sodium sulfate solution (100g sodium sulfate / 900g water). The surface control for salt blooming has daily observed for results up to 14d.

SILICONE BASED POWDERED WATER REPELLENT

COMPRESSIVE STRENGTH AT 1, 7, & 28 DAYS

0

5

10

15

20

25

30

1 7 28

CO

MPR

ESSI

ON

(MPA

)

TIME (DAYS)

BLANK 0.1% - P 750 0.2% - P 750 0.3% - P 750 0.4% - P 750 0.5% - P 750

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§  Specimens are made and cured according to ASTM C 109. §  From each formulation at least 3 specimen are prepared. §  Release agent is not used on the mold to avoid any possible interference.

*: REFERRED TO TOTAL AMOUNT OF DRY COMPONENTS

0

20

40

60

80

100

120

140

160

Mortar 0.1% 0.2% 0.3% 0.4% 0.5%

mm

% SITREN® P 750*

Flow (mm)

0

2

4

6

8

10

12

14

16

Mortar 0.1% 0.2% 0.3% 0.4% 0.5%

%

% SITREN® P 750*

Air Content (%)

NO INFLUENCE ON FRESH MORTAR PROPERTIES

AIR CONTENT & FLOWABILITY

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PROTECTION AGAINST ALGAES

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Concrete slabs with silicone based water

repellent (speciman middle)

1 year of outside exposure Only the speciman containing silicones

shows no dirt pick up and no growth of algae

Outperforming Most Competitive Products

Benefits are:

§  Efflorescence control

§  Outstanding water repellency

§  Reduced water absorption

§  Durability

§  Very good free-flow behavior

§  Paintable

§  High alkaline stability

§  Easy handling

§  Improvement of tensile adhesion strength

SILICONE BASED WATER REPELLENTS SET THE

BENCHMARK

JS

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In contrast to common metal soaps, Silicone based products provide long lasting performance and cannot be washed out. Stearates lose their effectiveness relatively fast.

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