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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
ready 2
Grouted zone around the tunnel with penetration length l and hydraulic conductivity* Kg
Dalmalm 2004
Correct grouting → Kg < K None correct grouting → Kg ≥ K (!)
ready press 3
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
ready press
15%
6
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
press
ready
7
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
ready press 8
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
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
ready
... for what ??
11
press ready
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
press ready 13
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
ready
press
press
14
Blaine 6000 [cm2/g]
superplasticiser
bentonite
ready
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
=
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
ready
press
press
CohesionOPC ˃˃ Cohesionwater (= 0)
ViscosityOPC ˃˃ Viscositywater
21
Water pressure tests (Lugeon tests)
press
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)
ready press
≤ 1.0
22
˃ 1.0 = fracturing !!!
press
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 ????
ready
Water velocity ~ 3m/s
= wash-out
26
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
ready 27
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
ready
press
28
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
ready 30
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)
ready
press
33
34
Permeation grouting in moraine (water glas) Fracturing by grouting
in sand (water glas) Fracturing by grouting
in till (PUR)
ready
Fault above tunnel invert (D&B) after wash-out of fill material
ca. 8m
ready
Fault above tunnel invert (D&B) after wash-out of fill material. Re-filling with OMR
press
x 30-40
35
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
ready
Héðinsfjarðargöng Project – face collapse at Ólafsfjördur Tunnel
38
Fault above tunnel invert before wash-out of fill material ready Fault above tunnel invert after wash-out of fill material 39
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)
ready
PUR as “hard” amber (Ólafsfjörður Tunnel) 41
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]
ready press press 44
OPC or PUR
??? Hydraulic conductivity < Lu ≈ 10-15 Winter conditions (temp. + 3-5 ºC)
High water velocity Big caverns
press ready
PUR
and OMR
45