TY - BOOK
T1 - Evaluation of Performance of Uniaxially and Isostatically Compressed Buffer Blocks
AU - Bohner, Edgar
AU - Kivikoski, Harri
AU - Salparanta, Liisa
AU - Löija, Mia
N1 - HUO: available later at Posiva portal
Project code: 100898
PY - 2017
Y1 - 2017
N2 - SKB and Posiva have two different reference methods for
production of buffer blocks: uniaxial and isostatic
compression, respectively. Both methods have been shown
to fulfil current requirements on buffer blocks. Yet the
comparisons of performance have not been made by blocks
produced of the exact same material.
The goal of the project was to test, compare and evaluate
the properties of the uniaxial and isostatic full-scale
buffer blocks with a diameter of 1800 mm and manufactured
from the same bentonite batch by the same predefined
parameters and technical properties. The same batch of
MX-80 bentonite with a water content of w = 17%, was used
for the comparative study. It was the intention to
perform the evaluation based on similar conditions, i.e.
at the same age, on the same size samples and using the
same test methods for both blocks. After all, a
full-scale block, manufactured by isostatic compression,
could not be made available. Therefore, the testing was
done on an isostatic block with a height of 1250 mm and a
diameter of 1200 mm, which is 2/3rd of the diameter of
the full-scale uniaxial block having a diameter of 1800
mm and a height of 500 mm.
From both blocks, several core samples were taken in the
vertical and horizontal directions. The core samples were
cut to prepare further specimens. The specimens were used
to determine their bulk density, water content,
compressive and splitting tensile strength and modulus of
elasticity. Further tests were performed to determine the
humidity adsorption, change in density and cracking
behaviour of the bentonite samples when stored in ambient
air with different relative humidity. Special samples in
the form of a plate were cut from both blocks. The
thermal conductivity of the bentonite plates was measured
with a heat flow meter. Based on the testing results the
properties and the behaviour of both blocks were compared
and evaluated in order to provide the basis for a final
decision on the future manufacturing technique for buffer
blocks.
AB - SKB and Posiva have two different reference methods for
production of buffer blocks: uniaxial and isostatic
compression, respectively. Both methods have been shown
to fulfil current requirements on buffer blocks. Yet the
comparisons of performance have not been made by blocks
produced of the exact same material.
The goal of the project was to test, compare and evaluate
the properties of the uniaxial and isostatic full-scale
buffer blocks with a diameter of 1800 mm and manufactured
from the same bentonite batch by the same predefined
parameters and technical properties. The same batch of
MX-80 bentonite with a water content of w = 17%, was used
for the comparative study. It was the intention to
perform the evaluation based on similar conditions, i.e.
at the same age, on the same size samples and using the
same test methods for both blocks. After all, a
full-scale block, manufactured by isostatic compression,
could not be made available. Therefore, the testing was
done on an isostatic block with a height of 1250 mm and a
diameter of 1200 mm, which is 2/3rd of the diameter of
the full-scale uniaxial block having a diameter of 1800
mm and a height of 500 mm.
From both blocks, several core samples were taken in the
vertical and horizontal directions. The core samples were
cut to prepare further specimens. The specimens were used
to determine their bulk density, water content,
compressive and splitting tensile strength and modulus of
elasticity. Further tests were performed to determine the
humidity adsorption, change in density and cracking
behaviour of the bentonite samples when stored in ambient
air with different relative humidity. Special samples in
the form of a plate were cut from both blocks. The
thermal conductivity of the bentonite plates was measured
with a heat flow meter. Based on the testing results the
properties and the behaviour of both blocks were compared
and evaluated in order to provide the basis for a final
decision on the future manufacturing technique for buffer
blocks.
KW - bentonite
KW - buffer block
KW - isostatic
KW - uniaxial
KW - compression
UR - https://www.posiva.fi/en/index/media/reports.html
M3 - Report
T3 - Posiva Working Report
BT - Evaluation of Performance of Uniaxially and Isostatically Compressed Buffer Blocks
PB - Posiva
CY - Eurajoki
ER -