Advanced Techniques for Testing of Cement-Based Materials

Preface

Contents

1 Acoustic Emission Characterization of Fresh Cement-Based Materials

1.1 Introduction

1.2 Overview of Acoustic Emission

1.3 Related Literature

1.4 Discussion

1.5 Conclusions

References

2 Ultrasonic Techniques for Determination and Monitoring Various Properties of Cementitious Materials at Early Ages

2.1 Introduction

2.2 Ultrasonic Techniques for Measuring Early Age Properties of CBM

2.2.1 Theoretical Basics

2.2.2 Different Types of Ultrasonic Techniques

2.3 Monitoring of CBMs at Early Ages

2.3.1 Determination of Different Time Periods Within Structure Formation Process

2.3.2 Determination of Setting Process

2.3.3 Monitoring of Microstructural Properties

2.3.4 Ultrasonic Testing and Early Age Mechanical Properties

2.4 Conclusion

References

3 Elastic Modulus Measurement Through Ambient Response Method

3.1 Introduction

3.2 EMM-ARM Testing Apparatus

3.2.1 Concrete Testing

3.2.2 Mortar Testing

3.2.3 Cement Paste Testing

3.3 Frequency Identification

3.3.1 Operational Modal Analysis (OMA)

3.3.2 Experimental Modal Analysis (EMA)

3.4 E-modulus Estimation

3.5 Comparison of EMM-ARM with Other Methods

3.5.1 Concrete

3.5.2 Cement Paste

3.6 Repeatability of E-modulus Estimations

3.6.1 Concrete

3.6.2 Cement Paste

3.7 Accuracy of the E-modulus Estimations

3.7.1 Concrete

3.7.2 Cement Paste

3.8 Conclusions

References

4 Monitoring the Viscoelastic Behaviour of Cement Based Materials by Means of Repeated Minute-Scale-Duration Loadings

4.1 Introduction

4.2 Physical Mechanisms of the Basic Creep

4.3 Development of a Test Protocol

4.3.1 Preliminary Observations Performed on Creep Test of Long Duration

4.3.2 Testing Devices

4.3.3 Parameters of the Protocol

4.4 Results and Data Treatment

4.4.1 Data Treatment

4.4.2 Impact of the Devices on the Determination of the Elastic and Creep Properties

4.4.3 Microstructural Interpretation of the Results

4.5 Application of the Repeated Minute-Scale-Duration Loadings

4.5.1 Modelling Basic Creep Since Setting Time

4.5.2 Identification of Concrete Properties by Means of Multiscale Modelling

4.6 Conclusion and Outlook

References

5 Monitoring of the Thermal and Autogenous Strain

5.1 Introduction

5.2 Physical Mechanisms

5.2.1 Autogenous Deformation

5.2.2 Coefficient of Thermal Expansion

5.2.3 Correlation Between the Development of the Autogenous Strain and the CTE

5.3 Test Setup

5.3.1 Cement Paste and Mortar

5.3.2 Concrete

5.4 Test Protocol and Data Treatment

5.4.1 Review of the Literature

5.4.2 Development of a New Test Protocol for Concrete

5.5 Investigations and Results

5.5.1 Sensitivity Analysis on the Determination of the CTE Induced by the Data Processing

5.5.2 Extension to Cement Paste and Mortar Scale

5.5.3 Correlation Between the Early Development of the CTE and the Autogenous Strain and the Setting

5.5.4 Further Recommendation for the Monitoring of the CTE and Autogenous Strain at Very Early Age

5.6 Conclusion and Outlook

References

6 Testing Concrete Since Setting Time Under Free and Restrained Conditions

6.1 Introduction

6.2 Test Rig Designed for the Study of the Risk of Cracking of Cement Based Materials

6.2.1 Passive Restrained Shrinkage Test

6.2.2 Active Restrained Shrinkage Test

6.3 The TSTM (Temperature Stress Testing Machine)

6.3.1 Principle of TSTM’s

6.3.2 History of the Development of TSTM’s

6.4 Design Testing System

6.4.1 Test Setup

6.4.2 Test Protocol for the Restrained Shrinkage

6.5 Applications

6.5.1 Monitoring of the Viscoelastic Properties Since Setting

6.5.2 Implementation of Non-destructive Methods on a TSTM Device

6.5.3 Testing Concrete in Its Plastic State

6.5.4 Influence of Cyclic Loading/Displacement on the Hardening Process of Grout Material

6.5.5 Structural Scale

6.5.6 Degree of Restraint

6.6 Conclusions

References

7 Adjustable Restraining Frames for Systematic Investigation of Cracking Risk and Crack Formation in Reinforced Concrete Under Restrained Conditions

7.1 Introduction

7.2 Motivation and Concept

7.3 Technical Specification of the Frames

7.3.1 General Setup and Functionality

7.3.2 Passive Frame for Simulation of Hardening-Induced Stress History

7.3.3 Activation of the Frame for Superimposition of Hardening-Induced Stresses with Additional Stresses During Service Life

7.3.4 Modified Frame for Investigation of Cracking in Thick Members

7.4 Selected Results

7.4.1 General Remarks on the Testing Programme Conducted So Far

7.4.2 Hardening-Induced Stress History and Risk of Early Age Cracking

7.4.3 Superimposition of Hardening-Induced Stressing with Further Imposed Deformations Representative for Service Life

7.4.4 Crack Opening During Service Life

7.4.5 Evolution of the Restraint Force During Cracking in Thick Members with Reinforcement Near the Surface

7.5 Conclusion and Outlook

References