Zement

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Wet Shotcrete Performance Laboratory Test,
Methods and influencing Factors in Practice
Dr. Peter BoosHeidelbergCement, Zentrallabor HC
Nord, Ennigerloh Dr. Martina Dietermann Heidelbe
rgCement, Entwicklung und Anwendung, Leimen
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Agenda

• Wet shotcrete
• HeidelbergCement pull-off test
• Laboratory shotcrete rig
• Influencing factors in practice
• Optimized cement for shotcrete application
• Summary

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Shotcrete, high performance product consisting of

addition
water
Cement
admixture




aggregates

non-alkaline accelerator
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Requirements on wet shotcrete
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Requirements on wet shotcrete
100
Assessment of accelerated solidification by using
the HC pull-off test
J3
10
J2
compressive strength MPa
J1
1
gt J2
0.1
0.01
0.01
0.1
1
10
100
time h
6
Requirements on wet shotcrete
100
J3
10
J2
compressive strength MPa
J1
1
0.1
Assessment of early strength develop-ment by
using the shotcrete rig
0.01
0.01
0.1
1
10
100
time h
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Agenda

• Wet shotcrete
• HeidelbergCement pull-off test
• Laboratory shotcrete rig
• Influencing factors in practice
• Optimized cement for shotcrete application
• Summary

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HeidelbergCement pull-off test
dissolver
dissolver axis
beaker
Cement paste
vertically positioned axis
electromagnetic force
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HeidelbergCement pull-off test
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Agenda

• Wet shotcrete
• HeidelbergCement pull-off test
• Laboratory shotcrete rig
• Influencing factors in practice
• Optimized cement for shotcrete application
• Summary

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Laboratory shotcrete rig
Film
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Recipes for the laboratory shotcrete rig
B1 B2 B3 B4
Cement kg/m³ 450 450 400 400
Fly ash kg/m³ - - 70 90
Limestone kg/m³ 150 150 - -
Water kg/m³ 203 225 214 218
(w/c)eq - 0.45 0.50 0.50 0.50
Plasticizer M.- v. Z. 2.0 1.0 1.5 1.0
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Results
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Results
Practise
Lab-test B2
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Agenda

• Wet shotcrete
• HeidelbergCement pull-off test
• Laboratory shotcrete rig
• Influencing factors in practice
• Optimized cement for shotcrete application
• Summary

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Influencing factors in practice
fresh concrete temperature???
ambient-temperature???
w/c-factor???
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Influence of w/c-factor and fresh concrete
temperature
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12
10
8
accelerator demand HC-pull-off test M.-
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4
2
w/c 0.40
w/c 0.50
w/c 0.55
0
14
16
18
20
temperature C
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Influence of fresh concrete temperature
TB 20 C
TB 26 C
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Influence of the ambient temperature
TL 10 C
TAir 7 C
TL 20 C
TAir 20 C
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Influence of the ambient temperature
temp.air
Cooling of concrete
temp.concrete
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Agenda

• Wet shotcrete
• HeidelbergCement pull-off test
• Laboratory shotcrete rig
• Influencing factors in practice
• Optimized cement for shotcrete application
• Summary

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Optimized cement for shotcrete application
before optimization
after optimization
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Agenda

• Wet shotcrete
• HeidelbergCement pull-off test
• Laboratory shotcrete rig
• Influencing factors in practice
• Optimized cement for shotcrete application
• Summary

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Summary

• Accelerator efficacy of cement-accelerator
  combination can be tested by using the new HC
  pull-off test
• The following early strength development can be
  reliably tested by using the HC shotcrete rig
• Essential external influences on shotcrete
  performance are
• Solidification w/c-factor
• Further strength development ambient temperature
• Optimized cement-accelerator combination show
  solidification between J2 and J3 and are gaining
  - even at low ambient air temperature -
  continuously strength.

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