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Rheology of high performance shotcrete Beaupré, Denis
Abstract
The main goal of this study was to develop high performance shotcrete and to provide a fundamental understanding of the shooting process. For this, a laboratory concrete pump, to pump and/or shoot a number of shotcrete mixes, and a rheometer, to measure the rheological properties on the fresh shotcrete, were designed and constructed. A model based on rheological behavior was finally developed to predict pumpability and shootability. The values of both flow resistance and torque viscosity were used to represent the rheological behavior of fresh shotcrete, which is similar to the Bingham model. Important fundamental relationships were obtained between rheological properties and pumping pressure, build-up thickness and compaction of shotcrete. With a new parameter, the fresh concrete aging rate, these relationships are used in a model which predicts pumpability and shootability. Production of high performance shotcrete can be carried out in two different ways: the “traditional method” consists of using superplasticizers while in the second method, the “concept of high initial air content” consists of using a very high air content to improve the workability. In both cases the requirements for good pumpability and shootability must be satisfied in order to be able to apply the shotcrete. These requirements are in conflict in terms of flow resistance: pumpability requires a low flow resistance while shootability requires a high flow resistance. The range of acceptable values for the flow resistance is reduced for mixes with high torque viscosity. The concept of a temporary high air content has some advantages over the traditional method: when compared to the use of superplasticizers only, the use of air, by reducing the torque viscosity, allows a wider range of acceptable values for the flow resistance to be maintained. Also, the compaction process allows a recovery of the flow resistance during shooting. Thus, this concept allows low water-cement ratio shotcrete having enhanced pumpability, shootability, strength, and durability to be produced. It could probably be an excellent way to avoid the use of accelerators which have adverse effects both on worker health and on concrete properties, especially the durability.
Item Metadata
Title |
Rheology of high performance shotcrete
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Creator | |
Publisher |
University of British Columbia
|
Date Issued |
1994
|
Description |
The main goal of this study was to develop high performance shotcrete and to provide a
fundamental understanding of the shooting process. For this, a laboratory concrete pump,
to pump and/or shoot a number of shotcrete mixes, and a rheometer, to measure the
rheological properties on the fresh shotcrete, were designed and constructed. A model
based on rheological behavior was finally developed to predict pumpability and
shootability.
The values of both flow resistance and torque viscosity were used to represent the
rheological behavior of fresh shotcrete, which is similar to the Bingham model. Important
fundamental relationships were obtained between rheological properties and pumping
pressure, build-up thickness and compaction of shotcrete. With a new parameter, the fresh
concrete aging rate, these relationships are used in a model which predicts pumpability and
shootability.
Production of high performance shotcrete can be carried out in two different ways: the
“traditional method” consists of using superplasticizers while in the second method, the
“concept of high initial air content” consists of using a very high air content to improve the
workability. In both cases the requirements for good pumpability and shootability must be
satisfied in order to be able to apply the shotcrete.
These requirements are in conflict in terms of flow resistance: pumpability requires a low
flow resistance while shootability requires a high flow resistance. The range of acceptable
values for the flow resistance is reduced for mixes with high torque viscosity.
The concept of a temporary high air content has some advantages over the traditional
method: when compared to the use of superplasticizers only, the use of air, by reducing the
torque viscosity, allows a wider range of acceptable values for the flow resistance to be
maintained. Also, the compaction process allows a recovery of the flow resistance during
shooting. Thus, this concept allows low water-cement ratio shotcrete having enhanced
pumpability, shootability, strength, and durability to be produced. It could probably be an
excellent way to avoid the use of accelerators which have adverse effects both on worker
health and on concrete properties, especially the durability.
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Extent |
4837068 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2009-04-08
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0050424
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
1994-05
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Item Media
Item Citations and Data
Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.