Buffer component manufacturing by uniaxial compression method

Small scale

Erika Holt, Jutta Peura

Research output: Book/ReportReportProfessional

Abstract

The purpose of this work was to gain better understanding about the method of uniaxial compression for the production of bentonite buffer components. Manufacturing by uniaxial was done in laboratory conditions to produce small cylindrical samples. The goal was to produce samples with sufficient bulk density according to the design needs, as well as to have homogenous density distribution and minimal defects in the sample. The testing was done using MX-80 bentonite as the reference material according to the production line plan. The water content was typically 17 %, though a few additional tests were done in ranges from 13 % to 22 %. Compression was done at 100 MPa for a target bulk density of approximately 2100 kg/m3. The final compressed sample size typically was 100 mm in diameter by 100 mm in height. Four different mould arrangements were used, including moulds with straight or inclined (0.5°) walls, moulds with insert tube liners, 3-part opening mould, and dual direction pressing mould. Approximately 10 different types of lubricants were used to reduce friction, including single-use spray, powder or grease lubricants, permanent mould liner coatings and single use foil liners. Post compression assessment included measurement of bulk and dry density over the height of the samples and visual observation of defects and/or cracking. In some cases tensile and compressive strength were tested. Microscopic investigations of the surfaces provided information about lubricant penetration to the bentonite. The results showed that it was possible to obtain uniform, defect free bentonite blocks by uniaxial compression. The best samples were obtained with the inclined mould walls and using a high-quality lubricant so that the bulk density variation was under 0.5 % across the sample height. Copper spray was the best lubricant, as well as the Teflon coating. Yet permanent coatings are a better alternative since they do not get entrapped within the bentonite during mould filling and compaction. Microcracks in some samples were attributed to sample extraction by pressing out of the mould. The 3-part opening mould resulted in samples without cracks, even when pressed without lubricant. The dual direction pressing resulted in production of homogeneous samples double in height compared to the diameter.
Original languageEnglish
Place of PublicationOlkiluoto
PublisherPosiva
Number of pages92
Publication statusPublished - 2011
MoE publication typeD4 Published development or research report or study

Publication series

NameWorking Report
PublisherPosiva Oy
No.2011-42

Fingerprint

manufacturing
buffers
lubricants
bentonite
sampling
pressing
methodology
coatings
bulk density
foil
cracking
friction
powders
copper
testing
water content

Keywords

  • bentonite
  • uniaxial
  • compression
  • mould
  • lubricant
  • laboratory
  • buffer
  • component
  • block

Cite this

Holt, E., & Peura, J. (2011). Buffer component manufacturing by uniaxial compression method: Small scale. Olkiluoto: Posiva . Working Report, No. 2011-42
Holt, Erika ; Peura, Jutta. / Buffer component manufacturing by uniaxial compression method : Small scale. Olkiluoto : Posiva , 2011. 92 p. (Working Report; No. 2011-42).
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abstract = "The purpose of this work was to gain better understanding about the method of uniaxial compression for the production of bentonite buffer components. Manufacturing by uniaxial was done in laboratory conditions to produce small cylindrical samples. The goal was to produce samples with sufficient bulk density according to the design needs, as well as to have homogenous density distribution and minimal defects in the sample. The testing was done using MX-80 bentonite as the reference material according to the production line plan. The water content was typically 17 {\%}, though a few additional tests were done in ranges from 13 {\%} to 22 {\%}. Compression was done at 100 MPa for a target bulk density of approximately 2100 kg/m3. The final compressed sample size typically was 100 mm in diameter by 100 mm in height. Four different mould arrangements were used, including moulds with straight or inclined (0.5°) walls, moulds with insert tube liners, 3-part opening mould, and dual direction pressing mould. Approximately 10 different types of lubricants were used to reduce friction, including single-use spray, powder or grease lubricants, permanent mould liner coatings and single use foil liners. Post compression assessment included measurement of bulk and dry density over the height of the samples and visual observation of defects and/or cracking. In some cases tensile and compressive strength were tested. Microscopic investigations of the surfaces provided information about lubricant penetration to the bentonite. The results showed that it was possible to obtain uniform, defect free bentonite blocks by uniaxial compression. The best samples were obtained with the inclined mould walls and using a high-quality lubricant so that the bulk density variation was under 0.5 {\%} across the sample height. Copper spray was the best lubricant, as well as the Teflon coating. Yet permanent coatings are a better alternative since they do not get entrapped within the bentonite during mould filling and compaction. Microcracks in some samples were attributed to sample extraction by pressing out of the mould. The 3-part opening mould resulted in samples without cracks, even when pressed without lubricant. The dual direction pressing resulted in production of homogeneous samples double in height compared to the diameter.",
keywords = "bentonite, uniaxial, compression, mould, lubricant, laboratory, buffer, component, block",
author = "Erika Holt and Jutta Peura",
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year = "2011",
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Holt, E & Peura, J 2011, Buffer component manufacturing by uniaxial compression method: Small scale. Working Report, no. 2011-42, Posiva , Olkiluoto.

Buffer component manufacturing by uniaxial compression method : Small scale. / Holt, Erika; Peura, Jutta.

Olkiluoto : Posiva , 2011. 92 p. (Working Report; No. 2011-42).

Research output: Book/ReportReportProfessional

TY - BOOK

T1 - Buffer component manufacturing by uniaxial compression method

T2 - Small scale

AU - Holt, Erika

AU - Peura, Jutta

N1 - Project code: 35777

PY - 2011

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N2 - The purpose of this work was to gain better understanding about the method of uniaxial compression for the production of bentonite buffer components. Manufacturing by uniaxial was done in laboratory conditions to produce small cylindrical samples. The goal was to produce samples with sufficient bulk density according to the design needs, as well as to have homogenous density distribution and minimal defects in the sample. The testing was done using MX-80 bentonite as the reference material according to the production line plan. The water content was typically 17 %, though a few additional tests were done in ranges from 13 % to 22 %. Compression was done at 100 MPa for a target bulk density of approximately 2100 kg/m3. The final compressed sample size typically was 100 mm in diameter by 100 mm in height. Four different mould arrangements were used, including moulds with straight or inclined (0.5°) walls, moulds with insert tube liners, 3-part opening mould, and dual direction pressing mould. Approximately 10 different types of lubricants were used to reduce friction, including single-use spray, powder or grease lubricants, permanent mould liner coatings and single use foil liners. Post compression assessment included measurement of bulk and dry density over the height of the samples and visual observation of defects and/or cracking. In some cases tensile and compressive strength were tested. Microscopic investigations of the surfaces provided information about lubricant penetration to the bentonite. The results showed that it was possible to obtain uniform, defect free bentonite blocks by uniaxial compression. The best samples were obtained with the inclined mould walls and using a high-quality lubricant so that the bulk density variation was under 0.5 % across the sample height. Copper spray was the best lubricant, as well as the Teflon coating. Yet permanent coatings are a better alternative since they do not get entrapped within the bentonite during mould filling and compaction. Microcracks in some samples were attributed to sample extraction by pressing out of the mould. The 3-part opening mould resulted in samples without cracks, even when pressed without lubricant. The dual direction pressing resulted in production of homogeneous samples double in height compared to the diameter.

AB - The purpose of this work was to gain better understanding about the method of uniaxial compression for the production of bentonite buffer components. Manufacturing by uniaxial was done in laboratory conditions to produce small cylindrical samples. The goal was to produce samples with sufficient bulk density according to the design needs, as well as to have homogenous density distribution and minimal defects in the sample. The testing was done using MX-80 bentonite as the reference material according to the production line plan. The water content was typically 17 %, though a few additional tests were done in ranges from 13 % to 22 %. Compression was done at 100 MPa for a target bulk density of approximately 2100 kg/m3. The final compressed sample size typically was 100 mm in diameter by 100 mm in height. Four different mould arrangements were used, including moulds with straight or inclined (0.5°) walls, moulds with insert tube liners, 3-part opening mould, and dual direction pressing mould. Approximately 10 different types of lubricants were used to reduce friction, including single-use spray, powder or grease lubricants, permanent mould liner coatings and single use foil liners. Post compression assessment included measurement of bulk and dry density over the height of the samples and visual observation of defects and/or cracking. In some cases tensile and compressive strength were tested. Microscopic investigations of the surfaces provided information about lubricant penetration to the bentonite. The results showed that it was possible to obtain uniform, defect free bentonite blocks by uniaxial compression. The best samples were obtained with the inclined mould walls and using a high-quality lubricant so that the bulk density variation was under 0.5 % across the sample height. Copper spray was the best lubricant, as well as the Teflon coating. Yet permanent coatings are a better alternative since they do not get entrapped within the bentonite during mould filling and compaction. Microcracks in some samples were attributed to sample extraction by pressing out of the mould. The 3-part opening mould resulted in samples without cracks, even when pressed without lubricant. The dual direction pressing resulted in production of homogeneous samples double in height compared to the diameter.

KW - bentonite

KW - uniaxial

KW - compression

KW - mould

KW - lubricant

KW - laboratory

KW - buffer

KW - component

KW - block

M3 - Report

T3 - Working Report

BT - Buffer component manufacturing by uniaxial compression method

PB - Posiva

CY - Olkiluoto

ER -

Holt E, Peura J. Buffer component manufacturing by uniaxial compression method: Small scale. Olkiluoto: Posiva , 2011. 92 p. (Working Report; No. 2011-42).