Wet Shotcrete Performance Laboratory Test Methods and influencing
Wet Shotcrete Performance – Laboratory Test, Methods and influencing Factors in Practice Dr. Peter Boos Heidelberg. Cement, Zentrallabor HC Nord, Ennigerloh Dr. Martina Dietermann Heidelberg. Cement, Entwicklung und Anwendung, Leimen
Agenda n Wet shotcrete n Heidelberg. Cement pull-off test n Laboratory shotcrete rig n Influencing factors in practice n Optimized cement for shotcrete application n Summary
Shotcrete, high performance product consisting of … Cement + aggregates + water + addition + admixture + non-alkaline accelerator
compressive strength [MPa] Requirements on wet shotcrete 100 J 3 10 J 2 J 1 1 0. 01 0. 1 1 time [h] 10 100
compressive strength [MPa] Requirements on wet shotcrete 100 10 Assessment of accelerated solidification by using the HC pull-off test J 3 J 2 J 1 1 > J 2 0. 1 0. 01 0. 1 1 time [h] 10 100
compressive strength [MPa] Requirements on wet shotcrete 100 J 3 10 J 2 J 1 1 0. 01 Assessment of early strength development by using the shotcrete rig 0. 1 1 time [h] 10 100
Agenda n Wet shotcrete n Heidelberg. Cement pull-off test n Laboratory shotcrete rig n Influencing factors in practice n Optimized cement for shotcrete application n Summary
Heidelberg. Cement pull-off test dissolver axis beaker Cement paste vertically positioned axis electromagnetic force
Heidelberg. Cement pull-off test
Agenda n Wet shotcrete n Heidelberg. Cement pull-off test n Laboratory shotcrete rig n Influencing factors in practice n Optimized cement for shotcrete application n Summary
Laboratory shotcrete rig Film
Recipes for the laboratory shotcrete rig B 1 B 2 B 3 B 4 Cement [kg/m³] 450 400 Fly ash [kg/m³] - - 70 90 Limestone [kg/m³] 150 - - Water [kg/m³] 203 225 214 218 (w/c)eq [-] 0. 45 0. 50 Plasticizer [M. -% v. Z. ] 2. 0 1. 5 1. 0
Compressive strength [MPa] Results 100 B 2 (450/150) 10 J 3 B 3 (400/70) J 2 B 4 (400/90) J 1 1 0. 01 0. 1 1 time [h] 10 100
Compressive strength [MPa] Results 100 Practise 10 J 3 Lab-test B 2 J 1 1 0. 01 0. 1 1 time [h] 10 100
Agenda n Wet shotcrete n Heidelberg. Cement pull-off test n Laboratory shotcrete rig n Influencing factors in practice n Optimized cement for shotcrete application n Summary
Influencing factors in practice fresh concrete temperature ? ? ? w/c-factor ? ? ? ambienttemperature ? ? ?
Influence of w/c-factor and fresh concrete temperature accelerator demand HC-pull-off test [M. -%] 14 12 10 8 6 4 2 w/c = 0. 40 w/c = 0. 55 0 14 16 18 temperature [°C] 20
compressive strength [MPa] Influence of fresh concrete temperature 100 TB = 20 °C 10 J 3 TB = 26 °C J 2 J 1 1 0. 01 0. 1 1 time [h] 10 100
compressive strength [MPa] Influence of the ambient temperature 100 TAir °C L ==107°C 10 J 3 TAir 20°C °C L ==20 ? J 2 J 1 1 0. 01 0. 1 1 time [h] 10 100
Influence of the ambient temperature 20 temperature [°C] Coo ling 15 temp. air of c temp. concrete onc rete 10 5 0 0 2 4 6 8 10 12 time [h] 14 16 18 20 22
Agenda n Wet shotcrete n Heidelberg. Cement pull-off test n Laboratory shotcrete rig n Influencing factors in practice n Optimized cement for shotcrete application n Summary
Compressive strength [MPa] Optimized cement for shotcrete application 100 before optimization 10 J 3 after optimization J 2 J 1 1 0. 01 0. 1 1 time [h] 10 100
Agenda n Wet shotcrete n Heidelberg. Cement pull-off test n Laboratory shotcrete rig n Influencing factors in practice n Optimized cement for shotcrete application n Summary
Summary n be Accelerator efficacy of cement-accelerator combination can tested by using the new HC pull-off test n The following early strength development can be reliably tested by using the HC shotcrete rig n Essential external influences on shotcrete performance are: o Solidification: w/c-factor o Further strength development: ambient temperature n Optimized cement-accelerator combination show solidification between J 2 and J 3 and are gaining - even at low ambient air temperature - continuously strength.
- Slides: 25