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ACI 237.2 2021

$34.67

ACI PRC-237-2.21: Form Pressure Exerted by Self-Consolidating Concrete: Primary Factors and Prediction Models – Report

Published By Publication Date Number of Pages
ACI 2021 36
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Given the high flowability and relatively fast casting rate of self-consolidating concrete (SCC), such concrete can exert high form pressure. Accurate assessment of form pressure is necessary from safety and economic points of view. The maximum form pressure and pressure decay are dependent on the structural buildup of the concrete at rest following placement, as well as on the placement parameters. The structural buildup at rest is affected by the thixotropy of the mixture. This report presents information on key parameters, including constituent materials; mixture proportioning; and casting parameters such as the casting rate, concrete temperature, and reinforcement percentage, affecting thixotropy and SCC form pressure. Prediction models available for estimating SCC form pressure are presented. Findings from two round-robin field studies conducted to validate these models are also discussed. This report should be of interest to concrete professionals, including concrete suppliers and formwork designers, because it covers: 1) the influence of SCC proportions and casting parameters on form pressure; 2) means to estimate formwork pressure with examples; and 3) techniques to measure formwork pressure in field applications. Keywords: form pressure; lateral pressure; self-consolidating concrete; structural buildup at rest; thixotropy.

PDF Catalog

PDF Pages PDF Title
3 TITLE PAGE
4 CHAPTER 1—INTRODUCTION
1.1—Introduction
5 1.2—Scope
1.3—Use of U.S. Customary Units in this report
6 CHAPTER 2—NOTATION AND DEFINITIONS
2.1—Notation
2.2—Definitions
CHAPTER 3—THIXOTROPY AND FORM PRESSURE
3.1—Thixotropy
7 3.2—Thixotropy test methods
11 3.3—Influence of thixotropy on form pressure
13 CHAPTER 4—EFFECT OF MIXTURE CHARACTERISTICS ON FORM PRESSURE
4.1—Introduction
4.2—Binder constituents and content
14 4.3—Water content
4.4—Aggregate characteristics
15 4.5—Chemical admixtures
16 CHAPTER 5—EFFECT OF CASTING PARAMETERS ON FORM PRESSURE
5.1—Introduction
5.2—SCC mixture temperature
5.3—Casting rate
17 5.4—Formwork characteristics
18 5.5—Reinforcement percentage
19 CHAPTER 6—PREDICTION MODELS FOR SCC FORM PRESSURE
6.1—Introduction
6.2—Model by Gardner et al. (2012)
6.3—Model by Khayat and Omran (2010b)
20 6.4—Model by Tejeda-Dominguez et al. (2005)
21 6.5—Model by Ovarlez and Roussel (2007)
CHAPTER 7—MEASUREMENT TECHNIQUES
7.1—Strain-gauge-based pressure sensor setup
23 7.2—Pressure reading graph example
7.3—Precautions and maintenance when measuring form pressure
CHAPTER 8—FIELD VALIDATION OF PREDICTION MODELS
8.1—Stockholm, Sweden, 2012
25 8.2—Toronto, Canada, 2014
28 8.3—Validation of models
29 8.4—Considerations for formwork design
CHAPTER 9—SUMMARY
CHAPTER 10—REFERENCES
Authored references
31 APPENDIX A—EXAMPLE CALCULATIONS
32 A1—Calculation of form pressure using model by Gardner et al. (2012)
A2—Calculation of form pressure using model by Khayat and Omran (2010b)
33 A3—Calculation of form pressure using model by Tejeda-Dominguez et al. (2005)
A4—Calculation of form pressure using model by Ovarlez and Roussel (2007)
ACI 237.2 2021
$34.67