4-presentation2 koehler test methods work ability rheology

Test Methods for Workability and Rheology of Fresh Concrete

Eric P. KoehlerW.R. Grace & Co.

ACI Fall ConventionNovember 2009November 2009

Outline

Categorization of Workability TestsCategorization of Workability Tests

Listing of Workability Tests• Conventional Concrete

• Self-Consolidating Concrete

• Paste Mortar GroutPaste, Mortar, Grout

Choosing the Right Test

Test Methods for Workability and Rheology of Fresh Concrete2

ACI 238 ReportReport categorizes and lists 69 test methods for workability and rheology

• Compiled from literature searchT t h i d f i d t

Today’s Presentation: Based on ACI 238 Report

• Tests have varying degrees of industry adoption

• New tests continue to being developed

Tests cover workability and rheologyrheology

Workability - that property of freshly mixed concrete or mortar which determines the ease and homogeneity with which it can be mixed, placed, consolidated and finished (ACI)consolidated, and finished (ACI).Rheology – the scientific description of the flow and deformation of matter

Workability is broadly defined: no single test measures all aspects ofsingle test measures all aspects of workabilityTests are available for many different applications

Filling ability finishability pumpability


Filling ability, finishability, pumpability, passing ability, segregation resistance, etc.

Categorization of Test MethodsT t b t i d i diff t

Empirical vs. Fundamental• Empirical (Workability): Tests simulate placement condition and measure a

l ( h di t ti ) th t i ifi t th t t th d

Test can be categorized in many different ways.

value (such as distance or time) that is specific to the test methodDifficult to compare results from one test to another

Multiple tests needed to describe different aspects of workability

• Fundamental (Rheology): Measure fundamental physical entities that are not specific to a test method

Results from different rheometers have been shown to be correlated

Results can be used to describe multiple aspects or workability

Static vs. DynamicStatic vs. Dynamic• Static: Concrete deforms under its on weight

• Dynamic: External energy (e.g. vibration) is added to cause deformation of concrete

Maximum Particle Size• Paste

• Mortar

• Concrete


Workability Level

Categorization of Test MethodsACI 238 t t i ti h d b NIST

CATEGORY DEFINITION EXAMPLES

Confined Flow The material flows under its own weight or under applied pressure through a narrow orifice

Compaction Factor

ACI 238 report uses categorization scheme proposed by NIST

under applied pressure through a narrow orifice.

Free Flow The material either flows under its own weight, without any confinement, or an object penetrates the material by gravitational settling.

Slump Test

Vibration The material flows under the influence of Vebe TestVibration The material flows under the influence of applied vibration. The vibration is applied using a vibrating table, dropping the base supporting the material, an external vibrator, or an internal vibrator.

Vebe Test

Rotational Rheometers

The material is sheared between two surfaces, one or both of which are rotating.

Parallel plate, coaxial cylinders, impeller rheometers

Tests for Very High Yield Stress

The material is subjected to relative higher forces than in other tests due to its stiff

Intensive Compaction TestYield Stress Concrete*

forces than in other tests due to its stiff consistency (no slump).

*not part of original NIST classification


Reference: Hackley, V. A., and Ferraris C. F., 2001, The Use of Nomenclature in Dispersion Science and Technology, Special Report 960-3, National Institute of Standards and Technology, Gaithersburg, MD.

Categorization of Test Methods: 69 TestsACI 238 t t i ti h d b NISTACI 238 report uses categorization scheme proposed by NIST


Concrete: Confined Flow Tests

Compaction Factor Test

Free Orifice (Orimet) Test

K-Slump TesterK-Slump Tester



Compaction Factor Test• Procedure

Fill top section with uncompacted concrete

Allowed concrete to drop to middle section, then to bottom cylinder

Measure mass of concrete in bottom cylinder due to dropping into cylinder (partially compacted)compacted)

Measure mass of concrete in bottom cylinder compacted by rodding (fully compacted)

• Results expressed as:

masspartially compacted/massfully compacted

• Suitable for full range of concrete yield stresses



Free Orifice (Orimet) Test• Procedure

Place concrete in apparatus

Open door at bottom of orifice

Measure time for concrete to discharge through orifice

• Steel bars may be added toSteel bars may be added to assess passing ability of SCC

• Developed for concrete mixtures that were too fluid for slump test



K-Slump Tester• Standardized as ASTM C 1362

• ProcedureInsert tube into concrete

Allow mortar to flow into tube for 60 s

Lower plunger to top of mortar; depth = K-slumpK slump

Remove tube from concrete

Allow mortar to flow out tube

Lower plunger to top of mortar; depth = WW

• ResultsK-slump related to slump

W related to compactabilityp y

K-W related to segregation resistance

• Suitable for low- and medium-yield stress concretes


Concrete: Free Flow Tests

Cone Penetration Test

Delivery-Chute Depth Meter

Delivery-Chute Torque MeterDelivery-Chute Torque Meter

Flow Trough Test

Kelly Ball Test

Modified Slump Test

Moving Sphere Viscometer

Ring Penetration Test

SLump Rate Machine (SLRM)

Slump TestSlump Test

Surface Settlement Test


Concrete: Free Flow TestsKelly Ball TestKelly Ball Test

• Formerly ASTM C 360, now discontinued

• Procedure• ProcedurePosition cylinder on top of concrete surface

Release cylinder

Measure penetration depth

• Results correlated to slump for a given concrete mixture proportion

Slump TestSt d di d ASTM C 143• Standardized as ASTM C 143

• ProcedureFill cone with concrete in three layers, compacting each layer

Remove slump cone

Measure distance concrete subsides

• Results have been shown to be correlated to yield stress, density, and


correlated to yield stress, density, and to a lesser extent plastic viscosity

Concrete: Free Flow Tests

Modified Slump Test• Procedure is the same as the slump test,

but the time for concrete to settle 100 mm is determinedmm is determined

• Yield stress is calculated from density and slump

Plastic viscosity is calculated from• Plastic viscosity is calculated from density and time to slump 100 mm

SLump Rate Machine (SLRM)• Automated device that measures vertical slump, horizontal slump flow, and

time to slump

Yi ld t i l l t d f ti f d it d l fl• Yield stress is calculated as a function of density and slump flow

• Plastic viscosity is calculated as a function of density, slump, slump flow, and time to slump


Concrete: Vibration Tests

Angles Flow Box Test

Compaction TestFlow Table Test (DIN)( )Inverted Slump Cone Test

LCL Flow Test

P R ldi T tPowers Remolding Test

Settlement Column Segregation TestThaulow Tester

Vebe ConsistometerVertical Pipe Apparatus

Vibrating Slope ApparatusVibrating Slope Apparatus

Vibratory Flow Meter

Vibropenetrator


Wigmore Consistometer


Compaction Test• Standardized as EN 12350-4

• ProcedureFill container without compaction

Apply vibration to compact concrete

Measure distance concrete compacts

• Results calculated as height ofResults calculated as height of concrete divided by height of container

Flow Table Test (DIN Test)• Standardized as EN 12350-5

• ProcedureFill cone in 2 layers, compacting each layerlayer

Remove cone

Lift plate 15 times

Measure horizontal spread

A li bl t f ll f l


• Applicable to full range of slumps


Settlement Column Segregation Test• Procedure

Fill column with concrete

Allow concrete to remain undisturbed for 1 minute

Subject concrete to 20 drops on drop table in 1 minute

Allow concrete to remain undisturbed for 5 minutes

Obtain samples from top and bottom sections, discard middle section

Wash samples through 5 mm sieve to retain coarse aggregate

• Results expressed as ratio of coarse aggregate in top section to coarse aggregate in bottom section

• Results indicate susceptibility to• Results indicate susceptibility to segregation



Vebe Consistometer• Standardized as ASTM C 1170

and EN 12350-3

• ProcedureFill slump cone with concrete

Remove slump cone

Move plastic disk over concreteMove plastic disk over concrete

Optional: apply surcharge load

Vibrate specimen

Measure time until mortar is in full t t ith di kcontact with disk

• Suitable for concrete with slumps less than 50 mm

• Use of slump cone to form• Use of slump cone to form specimen may be omitted


Concrete: Rotational Rheometers

Bertta Apparatus

BML Viscometer BTRHEOM RheometerCEMAGREF-IMG

Concrete Truck Mixer as a RheometerConsolis RheomixerCONVI Visco-ProbeFHPCM

Fresh Concrete Tester 101

ICAR RheometerIBB RheometerMixer DevicesMixer DevicesPowers and Wiler Plastometer

Rheometer-4SCCSoil Direct Shear Test


Soil Direct Shear Test

Tattersall Two-Point Device


Rheometers shear concrete through rotational movement.

Rheometers must be uniquely designed for concrete (primarily due to large aggregate size)

Coaxial Cylinders Parallel Plate Impeller

Typical Rheometer Geometries



Results can be expressed as a flow curve in:• Relative units (torque vs. speed)

• Absolute units (shear stress vs. shear rate), determined by calculation or ( ), ycalibration

Calculated/Calibrated Results (Ab l t U it )

Raw Measurements (R l ti U it )

(Pa)

The Bingham Model&

(Absolute Units)

m)

(Relative Units)

r St

ress

, γμττ += 0

slope = plastic viscosity (μ)

orqu

e (N

m

slope = H

Shear Rate, (1/s)

Shea

r

γ&

intercept = yield stress (τ0)

Speed (rps)

To

intercept = G


, ( )Speed ( ps)

Concrete Rheology: Non-Steady StateFlow Curve Test

ss (P

a)

concrete sheared at various rates

area between up and down curves due to thixotropy

Concrete exhibits different rheology when at rest than when flowing.

Static Yield Stressminimum shear stress to initiate flow from rest Sh

ear S

tres

slope = plastic viscosity

Dynamic Yield Stressminimum shear stress to maintain flow after breakdown of thixotropic structure

Plastic Viscosity

Shear Rate (1/s)

S

concrete sheared at constant lo rateStress Growth Test

intercept = dynamic

yield stress

Plastic Viscositychange in shear stress per change in shear rate, above yield stress

Thixotropy (Nm

)

concrete sheared at constant, low rate

maximum stress from rest= static yield stress

reversible, time-dependent reduction in viscosity in material subject to shear

Torq

ue


Time (s)

Concrete RheometersT tt ll T P i t Rh t IBB Rh t ICAR Rh tTattersall Two-Point Rheometer IBB Rheometer ICAR Rheometer

BML ViscometerBTRHEOM Rheometer Rheometer 4 SCCBML ViscometerBTRHEOM Rheometer Rheometer 4 SCC


Concrete Rheometer: Mixer MeasurementsDevices to Measure Workability or Rheology in a Mixer

Ready Mix Truck Stationary Mixerhydraulic pressure sensor

• CONVI Visco-Probe: Measures torque on rod and shaft in planetary mixer speed of

Devices to Measure Workability or Rheology in a Mixer

sensor rod and shaft in planetary mixer, speed of probe varies due to planetary motion, enabling calculation of rheological parameters

Sl M t f h d lislump display (in.)

control unit

• Slump: Measurements of hydraulic pressure (torque) and drum speed can be used to calculate slump.

• Rheology: Measuring at multiple drums • Consolis RheoMixer: Measures torque to

operate planetary mixer at various speeds,


speeds is analogous to concrete rheometer. reports rheological parameters

Concrete: Tests for Very High Yield Stress Mixtures

Intensive Compaction Test

Kango Hammer Test

Proctor TestProctor Test


Concrete: Tests for Very High Yield Stress Mixtures

Intensive Compaction Test• Utilizes gyratory compactor,

which applies compression and shear forcesshear forces.

• ProcedureFill specimen with known mass of concrete

Start application of compression and shear, continuously recording volume

Plot density and shear force vs. number of cycles

• Results can be evaluated as number of cycles to reach certain density or density after certain number of cycles.u be o cyc es

• Final compacted specimen can be tested for strength.


Tests for Self-Consolidating Concrete (SCC)

Confined Flow Tests• Fill-Box Test

• L-Box Test

• Simulated Soffit Test

• U-Box Test

V Funnel Test• V-Funnel Test

Free Flow Tests• J-Ring Test

• Slump Flow Test

Stability Tests• Column Segregation Test• Column Segregation Test

• Penetration Test for Segregation

• Wet Sieving Stability Test


Tests for Self-Consolidating Concrete (SCC)SCC is defined by its workability Conventional SCC is defined by its workability

• Filling ability – flow and consolidate under its own mass without vibration

• Passing ability – pass through s,

(Pa)

μ

τ0 Similar plastic i it

Concrete

Passing ability pass through confined spaces

• Segregation resistance – maintain homogeneous distribution of constituents he

ar S

tres

s

μ

viscosityNear zero

yield stress SCC

constituentsStatic segregation resistance – applicable when concrete is at rest

Dynamic segregation resistance – applicable when concrete is flowing

Shear Rate, (1/s)

Sh

γ&

τ0

In terms of rheology, SCC exhibits:• Near-zero yield stress: allows concrete

to flow under its own mass

• Similar plastic viscosity to conventional concrete: ensures segregation resistance


Yield stress is the main difference between SCC and conventional concrete.

Tests for Self-Consolidating Concrete (SCC)ASTM t t il bl t th th SCC ti i d d tl

Slump FlowASTM C 1611

J-RingASTM C 1621

Column SegregationASTM C 1610

Filling Ability Passing Ability Segregation Resistance

ASTM tests are available to measure the three SCC properties independently.

ASTM C 1611 ASTM C 1621 ASTM C 1610

• Cone used in inverted or • Slump cone placed in • Column filled with upright position

• Measure:• Slump flow – horizontal

spread

middle of j-ring• Measure:

• Difference in slump flow with and without j-

concrete and left undisturbed for 15 minutes

• Measure:spread• T50 – time to spread 50

mm• VSI – visual stability

i d

flow with and without j-ring

• Change in height between inside and outside of ring (not

easu e• Difference in coarse

aggregate content in top and bottom quarters


index outside of ring (not standardized)

quarters


L-Box• Concrete is placed in vertical section

and allowed to flow into horizontal sectionsection

• Results are expressed asBlocking ratio: H2/H1

Time to flow 200 or 400 mmTime to flow 200 or 400 mm

U-Box• Concrete is placed in one side of box

and allowed to flow into other side

• Results expressed as height of t h id f bconcrete on each side of box



Penetration Test for Segregation Resistance

• Concrete is placed in inverted l t i ll dslump cone, concrete is allowed

to stabilize for certain time, penetration head is positioned above concrete and released.

• Penetration depth is correlated to segregation resistance for given mixture proportion

S SWet-Sieve Stability Test• Concrete is placed in bucket and

left undisturbed for 15 min, then a portion of concrete is poured fromportion of concrete is poured from 500 mm onto a 5 mm sieve

• Results are expressed as ratio of mass passing sieve to mass


poured on sieve


V-Funnel Test• Concrete is placed in funnel, the gate at the bottom

of the funnel is opened, and time for all concrete to discharge from funnel is measureddischarge from funnel is measured

• Results have been shown to be correlated to viscosity


Tests for Paste, Mortar, and Grout

Flow Cone and Marsh Cone Tests

Lombardi Plate

Miniflow and Minislump TestMiniflow and Minislump Test

Rotational Rheometers

Turning Tube Viscometer

Vicat Needle Test

ViscoCorder

Wuerpel Device


Tests for Paste, Mortar, and GroutMini-Slump Test Flow Cone Test

Tests for paste, mortar, and grout are frequently adaptations of tests for concrete

Mini Slump Test Flow Cone Test

concrete• Mini-slump or mini-flow tests

• Flow cone or marsh cone

• Rotational rheometers

Other tests include:• Lombardi plate test L b di Pl t T tp

• Turning tube viscometer

• Vicat needle test

Wuerpel test

Lombardi Plate Test

• Wuerpel test


How to Choose the Right Test

Things to consider when choosing a test:• Parameters measured: workability or rheology

• Ruggednessgg

• Workability range

• Aggregate size restrictions

Cost• Cost

• Sample size

• Time to test

• Complexity and training requirements

• Data analysis requirements

• Size and weightg

• Number of people required

• Electricity requirements


Summary

Numerous concrete workability tests are available, with new tests continuing to be developed

There are numerous aspects of workability and different ranges of workability, resulting in the need for different tests

Rheology provides a fundamental description of flow, which can be related to different concrete applicationsdifferent concrete applications

Rheometers are available for use in the lab and field


4-presentation2 koehler test methods work ability rheology

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