13 Exchange Meeting

siennatearfulUrban and Civil

Nov 25, 2013 (3 years and 6 months ago)

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13
th

Exchange Meeting

The role of cementitious materials for deep
disposal of high
-
level waste in Boom Clay

Use of cementitious materials in the
PRACLAY experimental programme





Wim Bastiaens

ESV EURIDICE GIE

Mol, 29 January 2009

13
th

Exchange Meeting

29 January, 2009

WBa/
2

Introduction



PRACLAY
: PReliminAry demonstration test
for CLAY disposal of highly radioactive
waste



Aim
: to demonstrate the feasibility of the
reference design for deep disposal of HLW

13
th

Exchange Meeting

29 January, 2009

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The PRACLAY project

PRACLAY In Situ

PRACLAY Surface

(
Generic
)

(
Design specific
)

Demonstration experiments



Repository construction feasibility

Demonstration Experiments

Construction, handling and
performance of EBS (Engineered
Barrier Systems)

Examples:

Ophelie mock
-
up,
supercontainer construction,
backfill test ESDRED (EC)

Confirmation experiments


The PRACLAY Heater Test

Supporting studies (T
-
H
-
M)

Atlas, CLIPEX (EC), SELFRAC
(EC),TIMODAZ (EC), …

13
th

Exchange Meeting

29 January, 2009

WBa/
4

The PRACLAY project

PRACLAY In Situ

PRACLAY Surface

(
Generic
)

(
Design specific
)

Demonstration experiments



Repository construction feasibility

Demonstration Experiments

Construction, handling and
performance of EBS (Engineered
Barrier Systems)

Examples:

Ophelie mock
-
up,
supercontainer construction,
backfill test
ESDRED (EC)

Confirmation experiments


The PRACLAY Heater Test

Supporting studies (T
-
H
-
M)

Atlas, CLIPEX (EC), SELFRAC
(EC),TIMODAZ (EC), …

Ophelie Day

10/06/2004

www.euridice.be

Presentations by

Bart Craeye &

Lou Areias

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th

Exchange Meeting

29 January, 2009

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5

Section to be backfilled



~30 m long



~90 m³ of material

PRACLAY surface: ESDRED (EC)

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Exchange Meeting

29 January, 2009

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Prevent collapse of the gallery lining
(and potential damage of the
supercontainer)


Prevent/limit creep of Boom Clay


(with potential destabilization of the
surrounding host formation)



Main requirement is a high filling ratio


There are some constraints on the materials

The backfill material has two main
roles/functions

13
th

Exchange Meeting

29 January, 2009

WBa/
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Two backfilling techniques tested in the
scope of ESDRED


Backfilling by pumping a grout







Backfilling by projecting a granular material


13
th

Exchange Meeting

29 January, 2009

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Programme objectives: ‘grout technique’


Development of a grout with specific
requirements (related to operational and LT
safety aspects):


High pH (corrosion protection)


Sufficiently high thermal conductivity (> 1 W/mK)


Compressive strength between 3 and 10 MPa
(retrievability)


Limited quantity of chemical additives (RN complexes)
and no sulfur containing species (corrosion)


Hardening time < 4 days (operation)


Fluidity sufficient to fill a 30 m long section


13
th

Exchange Meeting

29 January, 2009

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Programme objectives: ‘grout technique’


Verify preparation aspect (logistics) at large scale



Verify emplacement aspect at large scale



Verify that grout properties (emplacement and
behaviour) are maintained under thermal load












Reduced scale test: 2/3, Ø2.5m




Full scale test: Ø3.5m

13
th

Exchange Meeting

29 January, 2009

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Grout composition


Binding medium


Portland cement (
CEM I
)


High compressive strength (
52.5 N
)


High Sulphate Resisting (
HSR
)


Low Alkali level (
LA
)


Limestone powder


Additive


Superplasticizer Glenium®


Sand


Calibrated river sand 0
-

4 mm, washed and
dried


13
th

Exchange Meeting

29 January, 2009

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Design of the reduced
-
scale mock
-
up

13
th

Exchange Meeting

29 January, 2009

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Reduced
-
scale test (June 2006)


Flow rate ~ 3 m³/h


Hardening < 4 days


No segregation observed


Hardened material homogeneous




Rheological properties of grout
were suitable



100 % filling ratio obtained


Main injection tube was sufficient




Design of main injection tube
was suitable



Properties of hardened material


Density = 2200 kg/m³


λ

= 1.6 W/mK (fully dried)


k = 10
-
12 m/s (water)




.

Grout composition was found
to be suitable for full
-
scale test

13
th

Exchange Meeting

29 January, 2009

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13

Construction and design of the full
-
scale
mock
-
up


Main injection

(at 25m depth)

Back
-
up injection

Vent

13
th

Exchange Meeting

29 January, 2009

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Full
-
scale test: grout preparation and
tests (April 2008)


2 cranes


3 trucks

(10 m³)


1 pump +
reserve




240 big bags


(1T, pre
-
mix)




88 m³ grout




On
-
site tests

13
th

Exchange Meeting

29 January, 2009

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Grout injection


Temperature: ~65
°
C


Time needed: +/
-

7 hours


Average flow rate: 15.1 m³/h (11.7


24
m³/h)



Pump breakdown (replacing it took ~1h)


Main injection tube is sufficient


Back
-
up was used after pump breakdown


About 2
-
3 m³ of water/grout was ejected
through the vent


13
th

Exchange Meeting

29 January, 2009

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17

Grout injection


4 days after the test


~99 % filled


Small gap at the top (filled with water)


About 900 l was removed (1.1 % of total volume)


Gap dimensions from 0.5 cm (end cover) to 5 cm
(front cover)


5 cm

0.5 cm

13
th

Exchange Meeting

29 January, 2009

WBa/
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Grout behaviour


The grout hardened partially and very slowly (


small scale test)



NOT caused by


Difference of compositions (chemical analyses)


Problem with cement quality (chemical analyses)


Segregation during pumping (not likely according to Magnel, CSTC, Glaser)



Different boundary conditions














W/C ratio during full scale test at the high end of the functioning range


Reduced scale test

Full scale test

Temperature

45
°
C

65
°
C

Diameter

2.5 m

3.5 m

Reinforcement
of the setup

Bars (


not impervious)





Metal sheet (


impervious)

13
th

Exchange Meeting

29 January, 2009

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Lessons learnt from backfill tests


Material development based on industrial
knowledge; properties +/
-

OK


Backfilling 30 m: yes we can!


The design of the mock
-
up and internal components
was OK (cf. injection tubes)


Logistic aspects are important


The saturation and design of the concrete lining of
the disposal galleries could have an influence


Further need to tailor the grout: larger functioning zone


Continuing theoretical/design studies (for SFC
-
1) to
translate knowhow from tests to repository configuration


13
th

Exchange Meeting

29 January, 2009

WBa/
20

The PRACLAY project

PRACLAY In Situ

PRACLAY Surface

(
Generic
)

(
Design specific
)

Demonstration experiments



Repository construction feasibility

Demonstration Experiments

Construction, handling and
performance of EBS (Engineered
Barrier Systems)

Examples:

Ophelie mock
-
up,
supercontainer construction,
backfill test ESDRED (EC)

Confirmation experiments


The PRACLAY Heater Test

Supporting studies (T
-
H
-
M)

Atlas, CLIPEX (EC), SELFRAC
(EC),TIMODAZ (EC), …

13
th

Exchange Meeting

29 January, 2009

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21

Construction history


Phase 1 1980
-

’87

pioneering + R&D



Phase 2 1997
-

’07

demonstration

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Exchange Meeting

29 January, 2009

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Construction feasibility


Use of cementitious materials in HADES
mainly linked to the lining


First shaft


Poured concrete

13
th

Exchange Meeting

29 January, 2009

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Construction feasibility


Use of cementitious materials in HADES
mainly linked to the lining


Experimental works / Test Drift


Unreinforced concrete segments


Wooden interlayers to limit ground pressure


Installed manually


13
th

Exchange Meeting

29 January, 2009

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Construction feasibility


Use of cementitious materials in HADES
mainly linked to the lining


Second shaft


Prefab segments + shotcrete + cast concrete


13
th

Exchange Meeting

29 January, 2009

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Construction feasibility


Use of cementitious materials in HADES
mainly linked to the lining


Connecting gallery / PRACLAY gallery


Unreinforced concrete segments


Wedge block technique


Installed with erector


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th

Exchange Meeting

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Construction feasibility


Evolution of the properties of the lining


Higher strength


Lower thickness


Manual


mechanised installation


Lower host rock disturbance


Limit overexcavation


Avoid additional convergence after lining installation

1st shaft
2nd shaft (sand)
2nd shaft (clay)
Test drift
Connecting gallery
PRACLAY gallery
Construction end
1982
1999
1999
1987
2002
2007
External diameter
4.3 m
4.5 m
4.5 m
4.7 m
4.8 m
2.5 m
Lining thickness
2 x 40 cm
30 cm
*
40 cm
*
60 cm
40 cm
30 cm
Installation method
Poured
Segments (mechanised)
Poured
Shotcrete + segments
(manual)
Segments (mechanised)
Segments (mechanised)
Rigidity
Rigid
Rigid
Rigid
Wooden interlayers
Rigid
Rigid / INOX interlayers
Host rock disturbance
Very large
NA
Large
Large
Small
Small
Compressive strength
C40/50
**
C40/50
C45/55
C45/55
C65/80
C80/95 and >
C125/150
***
*
Secondary lining thickness, primary lining is present
**
Based on test cube results
***
C125/150 is not an official strength class; >150MPa on a normalised cilinder was required
13
th

Exchange Meeting

29 January, 2009

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Construction feasibility


Monitoring of strains in lining (CG)


Correction for creep phenomena is important









External ground pressures


Test Drift: 1.6


2.4 MPa
(De Bruyn et al. 1995)


Connecting Gallery: 2.1


3.1 MPa
(Ramaeckers & Van Cotthem 2003)

0
100
200
300
400
500
600
700
800
jan '02
jul '02
jan '03
jul '03
jan '04
jul '04
jan '05
jul '05
jan '06
average strain (µstrain)
INTRA
EXTRA
13
th

Exchange Meeting

29 January, 2009

WBa/
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The PRACLAY project

PRACLAY In Situ

PRACLAY Surface

(
Generic
)

(
Design specific
)

Demonstration experiments



Repository construction feasibility

Demonstration Experiments

Construction, handling and
performance of EBS (Engineered
Barrier Systems)

Examples:

Ophelie mock
-
up,
supercontainer construction,
backfill test ESDRED (EC)

Confirmation experiments


The PRACLAY Heater Test

Supporting studies (T
-
H
-
M)

Atlas, CLIPEX (EC), SELFRAC
(EC),TIMODAZ (EC), …

13
th

Exchange Meeting

29 January, 2009

WBa/
30

The PRACLAY heater test


Demonstrate that thermal loading doesn’t compromise the
role of Boom Clay in the disposal system


Combination of excavation (EDZ) and thermal loading


Study the interaction between the host rock and the lining
(cf. retrievability)


Verify current knowledge of THM(C) processes


Large scale


heated section ~35m (~80
°
C)


Long term


heat during 10 years


13
th

Exchange Meeting

29 January, 2009

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The PRACLAY heater test


Some tailor
-
made concrete applications


Lining


C80/95 (“normal” wedge blocks)


Very high
-
strength concrete (Ceracem®,
Eiffage
)


End plug


Compressive concrete (
Solexperts
)


Grout

13
th

Exchange Meeting

29 January, 2009

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PRACLAY heater test: lining


Geotechnical load case


Host rock



2.5 MPa


Anisotropy



1.1 (1.4)


Thermal load


Temperature increase

~70
°
C


Temperature gradient

~10
°
C



Conservative calculation (no possibility for
dilation) leads to stresses in the lining up
to 110 MPa during the thermal phase



13
th

Exchange Meeting

29 January, 2009

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PRACLAY heater test: lining


C80/95 unreinforced concrete


Expansions joints to allow thermal dilation


Stainless steel foam panels, silicone rubber sheets


13
th

Exchange Meeting

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PRACLAY heater test: lining


Stainless steel foam panels


Elasto
-
plastic behaviour


Small compression before thermal phase


Start to compress before the concrete
fails (allow thermal dilation)


Compression tests have confirmed the
elasto
-
plastic behaviour


Test necessity of joints: rings without


Special concrete: > 125MPa on cylinder


Fibre reinforced concrete (Ceracem®)

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th

Exchange Meeting

29 January, 2009

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PRACLAY heater test: end plug


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Exchange Meeting

29 January, 2009

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Exchange Meeting

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Exchange Meeting

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Conclusions


EIG EURIDICE uses cementitious materials in on surface
and in
-
situ tests



Backfill experiments (ESDRED)


Demonstrate the feasibility of grouting technique


Give important input for future design



Cementitious materials are important construction
materials for a disposal site / URF



Concrete (lining) technology has evolved over time



Some tailor made concrete solutions were necessary to
cope with the specific experimental conditions of the
PRACLAY heater test