Part 30 MAPEI

“OPC, MC or PUR” III-2012

(Part 30 MAPEI, PP 2007, animation+p/r : 2012.03.20 final short version)

ready Copyright notice Unauthorised copying of this presentation as

whole or in parts in any form or by any means, electronic, photocopying, recording

or otherwise, without prior written permision is prohibited. 1

The seepage of water in hardrock occurs along channels within the discontinuities of the rock

mass. Between the discontinuities the rock material is often practically impermeable.

The conductivity of the rock mass depends on the properties of the discontinuities.

Holter, Hognestad, Garshol 2001

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Grouted zone around the tunnel with penetration length l and hydraulic conductivity* Kg

Dalmalm 2004

Correct grouting → Kg < K None correct grouting → Kg ≥ K (!)

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4 ready press

OPC

MC, UFC

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The real crack is not ”academic pipe” like in doctor’s thesis

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The groutability of fine cracks is related to the width of the crack and the grain size of

the grout material, expressed as a groutability ratio for rock in the following formula

(Weaver 1991):

For groutability ratios greater than 5, grouting is considered consistently possible.

For groutability ratios less than 2, grouting is not considered possible.

Hansen 2003

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15%

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D

1.0

d

2.0

Penetration of cement grouts; D/d vs. water-cement ratio (Axelsson, Gustafson 2007)

D/d

water-cement ratio OPC

D/d = min 6 (at too high pumping rate)

press

press

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The ability of a grout to penetrate cavities, channels and porous material (penetrability)

depends on two things: rheology and filtration tendency.

Extensive laboratory tests on stable, low w/c-ratio grouts show that the most significant limitation to

their penetrability is the tendency of cement grains to agglomerate into an impermeable filter cake

besides of flocculation due to presso-filtraction

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Flocculation means a gathering

together or clotting of fine particles in

a dispersed state to form lager

agglomerations. When Portland

cements and bentonite (especial in

high dosage) are mixed together with

water, the solid particles flocculate

due to electrostatic attraction

between the positive and negative

charge sites on the particles.

Bleed develops as the cement

particles settle due to the effects of

gravity and allow free water to bleed

from the suspension. If a grout has

high bleed capacity, it will not fully fill

the pore space within the soil or

fractures in a rock due to the bleed

water which forms as it sets.

For stable grouts, bleed should be as

low as possible (preferably less than

2%), but in no case should be more

than 5%.

Presso-filtration is a measure of bleed under

pressure. The pressure filtration coefficient is

a measure of how much water is forced out of

a sample under pressure in a given period of

time.

Injecting grouts into small apertures is similar

to pressing the grout against a filter material.

The “filtration tendency” of the grout is the

property of the grout whereby a plug of grain

can be formed at the crack opening or within

the crack. press ready press press 9

Ordinary Portland Cement - partially penetration

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Apparent viscosity measurements by means of Marsh Funnel (Marsh Viscosity) to the left and bleeding with the 1 liter traditional graduated cylinder to the right

Abreu J.V. ...... 2005

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... for what ??

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Penetrability meter test for OPC grouts (MC, UFC) instead of bleed test! Grout passed through different filters in penetrability meter test

press

Amount of passed through different used filters

0.10 mm

PLUG !!!

12

press

Higher Blaine value [cm2/g]

→ larger reactive surface

→ higher flocculation tendency

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Fine cement Surface Area = High (if you add fine fillers)

D95 = 50 microns

Very fine cement, but with much over sized

particles

Particle sizes of microcements

Microcement Surface Area = High

D95 = 10 microns

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press

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Blaine 6000 [cm2/g]

superplasticiser

bentonite

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The graph below summarizes the more peculiar characteristics of the MC grout mix from the injection

point of view.

According to those results:

- With ratios between 0.90 and 0.95 we have the best compromise between stability and viscosity.

- For lower ratios the mixes must be thinned with superplasticiser admixtures, while for higher ratios is

required a stabilization with bentonite.

The combination of bentonite and superplasticiser is lowering both the yield stress and viscosity of grout to

values under certain time comparable with chemical grouts.

press

press

press

15 press

=

16 press press press press ready

17 press press ready

18 press ready

OPC, MC, UFC - lower tendency for presso-filtration = better penetration

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Bleeding ?? Test for presso-filtration !!!

Superplasticiser ??? Deflocculant !!!

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press

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Typical rheological laws for two types of fluids

pressure (bar)

shear stress

grout flow (l/min)

shear strain or shear rate

viscosity α

yield stress (cohesion) Bindham yield point

Water = Newtonian fluid

OPC Binghamian fluid

Cement suspension ≠ water !!!!! Lugeon test is performed with Newtonian fluid Grouting is performed with Binghamiam fluid

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CohesionOPC ˃˃ Cohesionwater (= 0)

ViscosityOPC ˃˃ Viscositywater

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Water pressure tests (Lugeon tests)

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Amenability

Amenability is the ability of the particular grout to penetrate joints and other defects

premeated with water.

It is defined by the amenability coefficient (Ac) of the grout, which is expresssed as

follows:

The grout rheology is to be adjusted so as to maintain as high an amenability coefficient

as possible.

This should generally be greater than 75%, and preferably higher.

Lugr

Ac =

Luwa

where: Ac = amenability coefficient

Lugr = Lugeon permeability of the grout

Luwa = Lugeon permeability of water

(Nauts 1995)

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≤ 1.0

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˃ 1.0 = fracturing !!!

press

Convenient in low temperatures ready press 23

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fault 1

fault 2

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Leakage 1.000 l/s !!! No probe holes !!!

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fault

Rock grouting in Breiđalsheiđi and Botnsheiđi (Iceland) 1993-1994

water

Water pressure ~ approx. 60 bars Water inflow ~ 50 l/s/hole

Water temperature ~ +20 ºC

X Cement grouting ????

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Water velocity ~ 3m/s

= wash-out

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2-component PUR

Proposal: 2-component PUR

or

mineral component (OMC) (sequential grouting)

Component B - polyisocyonate

Component A - polyol

components A+B

1-component PUR

press press

Hydrophilic PUR – limited range of penetration!

press

components A+B

components A+B

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Free CO2 escapes further and helps 2nd

penetration

Blockage of the leakage.

Compressive semi-rigid foam

Hard resin

Sequential grouting with cement and

2-component polyurethanes

PU (A+B):

1. “Blocker grout” 2. Fine fissures grouting

cement

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Low temperature problems with cement based grouts

Climate

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Gravel and clay filled fault at the cutterhead

Stage 1: TBM in progress in water scenery Stage 2: huge water ingress from the fault;

TBM cutterhead passed the fault Stage 3: wash-out of the fill from the fault (TBM) Stage 4: material washed out from the fault

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Wide fault (coobles “cemented” with clay)

Question of time.... Water:+1 °C ÷ +65 °C

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There are two ways to set, or harden, liquid sodium silicates for grouting applications.

The first way is by lowering the silicate’s pH. This causes the SiO2 species to polymerize into a gel. Some setting agents will hydrolyze over time and form an a

cid that will set the silicate. By controlling the composition of the setting agent, and therefore the rate of hydrolysis, the gel time of the grout can be tightly controlled.

The second way to set a silicate grout is to react it with soluble metals to form insoluble metal silicates.

These grouts generally have higher strength and are lower in cost.

Typically, PQ’s N® sodium silicate is used for grouting applications. It is diluted to reduce its viscosity, so that it penetrates soils more easily.

The viscosity adjustment takes into account the soil permeability and the strength requirement of the grouted mass.

The strength of a silicate-grouted soil is influenced by several factors: concentration of silicate in the grout formulation composition and particle size distribution

of the soil selection and amount of hardening agents chemistry of the surrounding waters

Soil grouting and ground modification with sodium silicate is a sophisticated engineering application and requires specialized equipment and expertise.

Injekteringscement 30

d85 grout = 0,04 mm d15 soil_1 = 0,40 mm

d15 soil_2 = 0,24 mm

d15 soil_2 / d85 grout = 6 d60 soil_2 / d10 soul_2 = 2,40

d15 soil_2 / d85 grout = 10 d60 soil_2 / d10 soul_2 = 2,08

Groutability of soils press press press ready 32

Coarse grained crushed material, well “cemented” with hard clay after PUR grouting

Permeation grouting

PUR permeation in sand and gravel (low pressure grouting)

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Permeation grouting in moraine (water glas) Fracturing by grouting

in sand (water glas) Fracturing by grouting

in till (PUR)

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Fault above tunnel invert (D&B) after wash-out of fill material

ca. 8m

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Fault above tunnel invert (D&B) after wash-out of fill material. Re-filling with OMR

press

x 30-40

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Water inflow into Icelandic rock mass: - Ólafsfjördur Tunnel ready 36

Ólafsfjörður Tunnel. Water in front of the face: water ingress ~ 5-30 l/s/hole Ólafsfjörður Tunnel. Water in front of the face: water ingress in the hole ~ 50 l/s ready 37

Héðinsfjarðargöng Project - leakage at the face of Ólafsfjördur Tunnel

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Héðinsfjarðargöng Project – face collapse at Ólafsfjördur Tunnel

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Fault above tunnel invert before wash-out of fill material ready Fault above tunnel invert after wash-out of fill material 39

Fault above tunnel invert after PUR pre grouting

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Stone from the face grouted with PUR - solid form like amber of PU resin

(Ólafsfjörður Tunnel)

Stone from the face grouted with PUR - solid form like amber of PU resin

(Ólafsfjörður Tunnel)

Large fault grouted with PUR (Ólafsfjörður Tunnel)

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PUR as “hard” amber (Ólafsfjörður Tunnel) 41

cement particles

water

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Water is enemy to cement based grouts (dilution)

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water

polyurethanes

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PU resins love water for reaction

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Factor λ = relation between volume of material grouted / material still remaining in the rock mass after

hardening vs. ground water velocity in mm/min

WilkitFoam, GeoFoam λ = 15÷30 x

CarboPur λ = 3÷5 x

De Neef Scandinavia AB 1991

wash-out effect

15 mm/sec

λ

ground water velocity [mm/min]

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OPC or PUR

??? Hydraulic conductivity < Lu ≈ 10-15 Winter conditions (temp. + 3-5 ºC)

High water velocity Big caverns

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PUR

and OMR

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46

OPC ?? MC ?? PUR ??

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The right answer ?????

press press press

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THE END

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Thank You for Your attention!

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