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Advanced SeminarRheology of Construction Materials

Rheological measuring systems

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Content

• Overview• Finger, Ford cup• Capillary viscometer• Falling ball viscometer• Rotational viscometer• Rotational rheometer• Selected accessories

• Temperature control units• Measuring geometries• Modules

• Extensional rheometer

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How can you measure viscosity ?

Feed back to other physical quantities, viscosity value relative or absolute.Rheometer: additional measurements of other (elastic) material characteristics

Krebs-Stormer-viscometerRotational viscometer / - rheometer

Compression viscometer

Torsion viscometer

(Mikro) Faling ball viscometerLaray-viscometer

ChangelFord cup(High pressure ) Capillary viscometer

Finger

Device

Force, DisplacementRotation sensor

Force, DisplacementCompression

DampingTorsion

TimeFalling weight

Time

Time (Pressure, Displacement)

Volum flow

Resistance (Force, Pressure)Biosensor

Measured quantityPrinciple

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Testing of Viscosity: Finger

... the cheapest viscometer

Advantages:+ cheap+ easy handling+ fast+ easy cleaning

Disadvantages:- relative- no reproducability- risky→ hazardous materials

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Ford-Cup

Disadvantages:- relative, type of cup and dye have to be

statede.g. DIN-cup Type A Dye Nr. 4

- no temperature control- wrong times for non-Newtonian fluids- not suitable for fluids with yield point

Method:Measurement of time ∆t (for a definedvolume), seconds as an index for theviscosity

Advantages:+ cheap+ easy handling /robust+ fast+ easy cleaning

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Method:The time is measured how long it takes for the fluid to pass two marks

Capillary viscometer (Gravity is the driving force)

Advantage:+ Relatively cheap+ Very precise for low and medium

viscosities+ Can be calibrated+ Absolute for Newtonian fluids

Disadvantage:- Long measuring time- High cleaning effort- Labor intensive (manual version)- relative values - for Non-Newtonian

fluids- Doesn't work for samples with a yield

stress- Limited operating temperature range

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Result:

ν - viscosity (kinematic) [ mm2 / s ] η = ν * ρ

C4 - Capillary constant,

depends on the used capillary and has to be determined by calibration

Boundary condition: L/D > 30 (L: length, D: diameter)

Application:Low viscous fluidse.g. oils

Capillary viscometer (Gravity is the driving force)

ν = C4 * ∆ t

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Method:The sample is pressed with a pistonthrough the capillary. Measurement of thepressure drop ∆p and the volume flow Q

High pressure capillary viscometer

Advantage:+ High shear rates+ Less friction heating because

alway new sample is feeded+ Calibration possible+ Absolute

Disadvantage:- High price- For test with rod capillary three test

are necessary for the Bagley-correction

- Not for low viscous materials- Cleaning

Calculations:

∆p = p1 - p2

τ = R/(2L) * ∆p

γ = 4/(π R3) * Q

η = π R4/8L * ∆p/ Q

Application: Polymers

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Method:Measuring the falling time of a ball bymeasuring marks in a tube with 10°inclination

HAAKE Falling Ball Viscometer Typ C Höppler (DIN 53015 / ISO 12058)

Advantages:+ High accuracy+ Temperature easy to control+ Absolute results for Newtonian

liquids+ Calibration+ Wide viscosity range+ Closed system

Disadvantages:- Long measuring time - Time consuming cleaning effort- Labour-intensive- Relative results for Non-Newtonian

liquids- Limited to transparent samples

without yield point- Sample density required

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Applications:- Low viscous fluids

e.g. oils- Evaporating fluids / solvents

e.g. toluene- Gases

HAAKE Falling Ball Viscometer Typ C Höppler (DIN 53015 / ISO 12058)

Result:

η - Viscosity (kinematic)

K - Calibration factor for the ball, Depends on the diameter of the ball and tube, has to be calibrated

η = K*(ρk - ρFl )*∆ t

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Rotational Viscometer / Rheometer (relative or absolute)

Method:Torque measurement at a given rotationalspeed (CR-Method)Deformation measurement (torque) at agiven torque (CS-Method)Differentiation: Searle-, Couette-type

Advantages:+Wide range of viscosity,

temperature and shear rate+Applicable for Non-Newtonian

liquids and samples with yieldpoint

+Calibration (absolute measuringsystems)

Disadvantages:- Partially cleaning intensive

(cup and rotor)- Slightly limited accuracy

CR-Method CS-MethodMotor

Bearing of measuring shaft

Joint

Measuring and temperature cell

Torque-,Deformation-

sensor

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Method:Rotational viscometer with sensorgeometry (flow field can not be calculated) In most cases measuring cell withouttemperature control

Rotational Viscometer (relative)

Advantages:+ Easy handling+ Quick measurement+ Minimal cleaning effort+ Reasonable in price

Disadvantages:- Relative results for Non-

Newtonian liquids- Comparable results only using

same sensor and same measuringconditions (r.p.m., sensor)

- Faulty viscosity readings due to variation in temperature

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Method:Rotational rheometer with coaxial cylinders,Cone-Plate and Plate-Plate geometries witha calculable flow field

Rotational Rheometer (absolute)

Advantages:+ Absolute readings, calibration+ Modularity thanks different

temperature control units, measuring geometries and accessories

+ Minimal cleaning (P/C and P/P) + Small sample volume (P/C and

P/P)+ Computer controlled

measurement, i. e. user-independent, datadocumentation

Disadvantages:- Price- High cleaning effort (cylinder

measuring geometry)

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Overview about Temperature Control Units* * HAAKE RheoStress 600 and HAAKE MARS available.

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Overview about Measuring Geometries

Coaxial cylinder geometries:- acc. to DIN 53018- acc. to ISO 3219- Mooney/Ewart-system- Double gap acc. to DIN 54453

Plate/Plate- and Cone/Plate

Relative measuring geometries- Brookfield – spindles acc. to ISO 2555- Pin- and vane rotor- Krebs rotor- geometries with serrated surface- …

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Subjective impression of the sample

Low to medium viscosity

easy to clean

High viscous, pastes,

hard to clean

Large particles

sedimentation, separation

Coaxial cylinders

in various

dimensions

Cone/plate

(without particles)

Plate/plate

(with particles)

Special sensors

vane

or

helical groovedsensor

How to choose the measuring geometry

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Coaxial Cylinders

Couette – MethodRotor fix, measuring cup rotates (1888, Couette)+ No Taylor vortex+ Drive unit and torque sensor mechanical separated+ Structural disadvantages (temperature controller rotates)

Searle – MethodeRotor rotates, measuring cup fix (1912, Searle).Common method for commercially available rheometers . + Structural advantages- Taylor vortexes at high rotation speed and low viscosity

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Related to rotor surface

τi = 1 / ( 2π * L * Ri2 cL) * Md = A * Md

γi = 2 * Ra2 / (Ri

2 - Ra2) * 2π / 60 * n = Mk * n

Information and calculations for measuring geometries acc. to Searle method.

Coaxial Cylinders

Shear stressτ(r) = Md / ( 2π * L * r2 )

Shear rateγ(r) = 2 * Ri

2 * Ra2 / (Ri

2 - Ra2) / r2 * ω

Md – Torque [Nm]ω – Angular Velocity [1/s]

ω = ( 2π * n ) /60v(r) = ω * r

n – Rotation speed [1/min]δ – Ratio of radiie

δ =Ra / Ri

cL – Coefficient of resistance

A

Mk.

.

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Coaxial Cylinders acc. to DIN 53018

Application:Samples with medium viscosities+ High accuracy- Cleaning efforts- Not suitable for temperature ramps

(expansion of air bubble)- Sample volume- High inertia

L > 1,5 * Ri

δ = Ra / Ri < 1,10

LS= 3 * (Ra - Ri )cL = 1

LS

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Coaxiale Cylinders acc. to ISO 3219

Application: Samples with medium up to higher viscositiesStandard geometry+ Easy Filling+ Suitabe for temperature rampes- Cleaning efforts- Sample volume- Higher inertia

L > 3 * Ri L‘‘ = Ri

δ = Ra / Ri < 1,0847 α = 120° + 1°L‘ = Ri cL = 1,1

τi = 1 / ( 2π * L * Ri2 * cL ) * Md

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Coaxiale Cylinders acc. to DIN 54453

Application:Samples with low viscositiesMeasurements at higher shear rates+ Samples volume+ Temperature control- Cleaning effort- Higher inertia

L > 3 * R3

δ = R2 / R1 = R4 / R3 < 1,15

τi = 1 / ( 2π * L * (R22 + R3

2)) * Md

γi = 2 * δ2 / (δ2 - 1) * 2π / 60 * n.

As special with helicalgrowings againstsedimentation

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Cone/Plate measuring geometry acc. to ISO 3219

Application:Samples with medium up to high viscosities+ Shear rate within measuring gap is constant+ Easy cleaning+ Small sample volume+ Fast and accurate temperature control+ Low inertia- Correct gap setting necessary

R

Hα

τ = 3 / ( 2π * R3 ) * Md = A * Md

γ = 1 / tan α * ω ∼ 2π /(α * 60) * n = Mk*n

α < 4° Recommendation: α = 1°

.

"Truncation"

Truncation >3 x bigger particle size

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Plate/Plate measuring geometry acc. to DIN 53018

Application:Samples with medium up to high viscositiesWith particles+ Easy cleaning+ Variation of shear rate range due to variable

setting+ Small sample volume+ Low inertia+ As disposable geometries available+ Temperature ramps- Shear rate within gap not constant H

R

τ (R) = 2 / ( π * R3 ) * Md = A*Md

γ (R) = v / H = ω * R / H = 2π * R /(H * 60) * n

H << R

Mk

.

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1,0E-04

1,0E-02

1,0E+00

1,0E+02

1,0E+04

1,0E+06

1,0E+08

1,0E+10

1,E-03 1,E-02 1,E-01 1,E+00 1,E+01 1,E+02 1,E+03 1,E+04 1,E+05

Shear rate (1/s)

She

ar s

tress

(Pa)

1,E-04

1,E-02

1,E+00

1,E+02

1,E+04

1,E+06

1,E+08

1,E+10

Visc

osity

(mP

as)

Recommended measuring range

Cone 20 mm/1°

Cone 60 mm/1°

η = 10 Pa·s

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Double cone geometry

Application:Samples with low up to medium viscosities+ Evaporation blocked+ High accuracy+ Low sample volume+ Easy Cleaning- Sample temperature- Gap setting- Inertia higher than

standard cone /plate geometry

Double cone geometry as a quasi closed measuring cell.

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Disposable measuring geometries

Application: For measurements• on samples with curring behaviour• with high cleaning efforts

+ No cleaning necessary+ Higher measurement rate- Set-up measuring device- Lower Parallelism than standard

geometry

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Measuring geometries with serrated surface

Application: For samples with• Slippage effect• Hard surface

+ Improvement of contact betweensample and measuring geometry

- Quasi absolut geometry(reduced accuracy)

- Higher cleaning effort

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Relative measuring geometries

Application: Samples, which can not be measured witha standard geometry due to:

big particlessedimentation…

+ Easy handling+ Flexibiliy of design- Relative- Temperature control

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Measuring Cell for Construction Materials

Application: Rheological properties of fresh building materials

+ Easy and quick adaptation of the measurement geometry to new materials

+ Easily adaptable serration profile+ Vane sensors with various diameters + Prevention of slippage layer formation+ Measurement in both rotational and oscillatory

mode+ Large specimens possible + Robust detailing of equipment+ Optional temperature control

- Shear rate within gap not constant- Temperatur control

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Measuring Cell for Bitumen

Application: Determination of properties acc. to SHRP à Aging behaviourà Deformation behaviour

(Measurement of application behaviour at 135°C in rotational mode)

+ Easy sample trimming in plate / platemeasuring geometrie (8, 25mm)

+ Water temperature controlled+ Measurement in both rotational and oscillatory

mode- Temperature range 5 up to 95°C

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RheoScope Module

Combination of two analytical test methods:Correlation between rheological properties

und structur

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HAAKE MARS + RheoScope Module

Example:Polyethylene

Rheological Data

Images

Click: Video

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HAAKE CaBER 1 (Capillary Breakup Extensional Rheometer)

Sample

Laser-micrometer

• Extensional flows occur in many industrial processesand applications and influence these processes often to a great extent.

• As a consequence the knowledge of extensional properties is important.• Extensional properties can not be measured with rotational rheometers.

[Click Image to repeat animation.

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Questions?