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Presented By:James A. Davies, P.Eng.
Advanced Construction Techniques Ltd.3935 Lloydtown Aurora
Road
Kettleby, OntarioL0G 1J0
Toll Free Telephone: 877-373-7248Email: [email protected]
State of the Art in Grout Mixes
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BALANCED STABLE GROUTS
Definitions Theory Materials Testing
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Definition
Balanced Stable Cement Grout
A homogenous balanced blend of water and cementcombined with
selected additives and admixtures
producing a product with zero bleed, low cohesion andgood
resistance to pressure filtration.
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Balanced Stable Grout
GroutMixture
Balanced Stable Grout
Optimal Blendof physical &rheological
properties forapplication
Zero BleedHomogeneous
WaterCementAdditives
Admixtures
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Unstable Grout Mixtures
Variable Rheology Poor Particle Orientation High Segregation
& Sedimentation High Pressure Filtration Coefficient
Unpredictable Behavior Unstable During Injection Marginal
Durability High Bleed Potential
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Theory
Low cohesion Viscosity consistent with acceptable
penetration rate Minimal to zero bleed Constant rheology during
application Dispersed particles High durability
What are the desired properties of a cementbased suspension
grout?
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Grouting Theory - Neat Cement Grouts
P
P
Refusal penetration controlled by pressure,cohesion, changing
rheology clumping,and bridging
Substantial water loss throughpressure filtration
Densificationof Grout
Post-grout Bleed Channels
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Neat Cement Grouts
Bleed
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Grouting Theory - Balanced, Stable Grouts
P
Refusal penetration controlledby pressure and cohesion
Minimal water loss throughpressure filtration
Minor Densificationof Grout
Zero or Negligible BleedChannels
P
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Balanced Stable Grouts
Bleed
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Grout Injection Theory
Stabilized vs. Neat Grouts
Neat Grouts
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Grout Injection Theory
Stabilized vs. Neat Grouts
Neat Grouts
Clumping and Bridging
Start of Refusal Pressure Builds
Limited Penetration DueTo High Cohesion
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Grout Injection Theory
Stabilized vs. Neat Grouts
Neat Grouts
Densification of Grout
Pressure Filtration
Substantial Water Loss
Refusal Controlled by Pressureand Cohesion
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Grout Injection Theory
Stabilized vs. Neat Grouts
Neat Grouts
Post Grout Bleed Channels
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Grout Injection Theory
Stabilized vs. Neat Grouts
Neat GroutsMORE HOLES
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Grout Injection Theory
Stabilized vs. Neat Grouts
Stabilized Grouts
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Grout Injection Theory
Stabilized vs. Neat Grouts
Stabilized GroutsMinor Densificationof Grout
Minimal Water Loss ThroughPressure Filtration
Refusal Controlled by Pressureand Cohesion
Greater Penetration DueTo Lower Cohesion
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Grout Injection Theory
Stabilized vs. Neat Grouts
Stabilized Grouts
Minimal Bleed Channels
Grout placement isextremely effective resultingin a more durable
treatment
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Characteristics of Balanced StableCement-Based Suspension
Grouts
Cement + water + additives +admixtures
Minimal to zero bleed High resistance to pressure filtration
Organized particles due to electrostatic
and chemical interaction High durability
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Characteristics of UnstableWater Cement Grouts
Cement + water Considerable bleed potential Low resistance to
pressure filtration Unorganized particles Lower durability
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Advantages of Balanced Stable Grouts Dispersed structure, stable
rheology and lower cohesion result in increased
penetrability and greater radius of grout spread
Minimal to zero bleed The fractures that are filled remain 100%
filled
Increased penetration and minimal to zero bleed result in lower
residualpermeability
Lower residual curtain and grout matrix permeability result in
increaseddurability
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Materials
Bentonite Silica Fume Flyash (Type C or F) Welan Gum Dispersant
(Super Plasticizer)
Common Additives to Balanced Stable Grout
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Bentonite Product
Natural sodiummontmorillonite clayproduct.Typical dosage is 2-8
% byweight of cement.Should be pre-hydratedand added as a
slurry.
Characteristics
AdvantagesReduced pressure filtrationReduced final bleedEnhanced
stability
DisadvantagesIncreased cohesionIncreased viscosity
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Silica Fume Product
By-product of the productionsilicon.Very fine
sphericalparticulate.Typical dosage between 4-8% by weight of
cement.
Characteristics
AdvantagesIncreased penetrabilityReduced final
permeabilityEnhanced durabilityWater repellantReduces pressure
filtration
DisadvantagesIncreased Strength
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Welan Gum Product
High molecular weightbipolymer.Used to increaseresistance to
pressurefiltration and for artesianconditions.Typical dosage is 0.1
% byweight of cement.
Characteristics
AdvantagesReduces pressure filtrationReduced segregationEnhanced
water repellant
.DisadvantagesIncreases cohesion
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Dispersant Product
Naphthalene sulfonatebased.
Enrobes cement particleswith a negative charge soparticles
repell.
Typical dosage is 1- 2% byweight of cement.
Characteristics
AdvantagesIncreased penetrabilityIncreased pumping time
.DisadvantagesIncreases set time
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Testing
Properties Test UnitsCohesion Viscometer PaViscosity Marsh
Funnel SecPressure Filtration Filter Press KpfBleed Cylinders
%Density Mud Balance #/ft3Set Time Vicat Needle HrsCompressive
Strength Cubes psi
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Cohesion Testing
Viscometer Test Cohesion
pascals (Pa)
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Evolution of Cohesion
Evolution of Viscosity from Shear Tube Test
1
10
100
1,000
10,000
0 180 360 540 720 900 1080 1260Time (minutes)
Shea
r Str
engt
h (P
a)
Mix B Mix C Mix D Mix E Mix F
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Viscosity (Marsh Funnel) Viscosity Reading
seconds
Measure of flowabilityof fluid grout
Water = 28 sec
Grout = 32 70 sec
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Pressure Filtration Testing
volume of water ejectedKpf =
_____________________________________________________
initial volume of grout x (filtration time (min))1/2
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Pressure Filtration Coefficients
0
0.01
0.02
0.03
0.04
0.05
0 5 10 15 20 25 30 35
Time (minutes)
Coe
ffic
ient
(1/m
in^-
1/2)
Mix A Mix B Mix C Mix D Mix E Mix F
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Mud Balance
Measures Density
Useful test for qualitycontrol on mixconsistency
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Set Time
Vicat NeedleInitial set 25 mmFinal set 0 mm
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THANK YOUPresented By:
James A. Davies, P.Eng.Advanced Construction Techniques Ltd.
3935 Lloydtown Aurora RoadKettleby, Ontario
L0G 1J0Toll Free Telephone: 877-373-7248
Email: [email protected]
