10. Creep of Concrete

1.1 Definition

Creep is the gradual deformation of concrete under constant stress over time.

1.2 Mechanism of Creep

Creep in concrete is a time-dependent deformation that occurs under sustained loading due to its viscoelastic nature.

1.3 Types of Creep

The section details the various types of creep in concrete, including basic creep, drying creep, and autogenous creep, each resulting from different environmental and material conditions.

1.4 Factors Affecting Creep

Creep in concrete is influenced by various factors such as stress level, water-cement ratio, age at loading, and environmental conditions.

1.5 Measurement of Creep

Creep is measured through specific test setups that isolate deformation caused by stress over time.

2.1 Definition

This section defines creep and shrinkage in concrete, highlighting their characteristics and implications for structural integrity.

2.2 Types of Shrinkage

This section outlines the various types of shrinkage that concrete can undergo, including plastic, drying, autogenous, and carbonation shrinkage.

2.3 Factors Affecting Shrinkage

This section highlights the key factors influencing the shrinkage of concrete, emphasizing how material properties and environmental conditions contribute to shrinkage behavior.

2.4 Measurement of Shrinkage

This section discusses the methods for measuring shrinkage in concrete, highlighting the importance of standard test specimens and measurement techniques.

4.1 For Creep

Creep refers to the gradual deformation of concrete under constant stress over time.

4.2 For Shrinkage

This section discusses the shrinkage of concrete, highlighting its types, influencing factors, measurement methods, and mitigation strategies.

6.1 Creep Modeling Approaches

This section discusses various mathematical models used to predict the long-term creep behavior of concrete in structural engineering.

6.2 Shrinkage Prediction Models

Shrinkage prediction models are essential for understanding how drying, environmental conditions, and concrete properties affect the long-term volume reduction in concrete.

7.1 Example – High-Rise Building

7.2 Example – Bridge Segmental Construction

8.1 Creep Test Setup

This section discusses the setup required for conducting a creep test on concrete specimens to assess their time-dependent deformation under sustained loads.

8.2 Shrinkage Test Setup

This section outlines the setup for measuring concrete shrinkage, detailing the use of sealed and unsealed specimens under controlled humidity conditions.

9.1 Precast and Prestressed Concrete

This section explores the implications of creep and shrinkage in precast and prestressed concrete, highlighting their effects and mitigation strategies.

9.2 High-Performance Concrete (HPC)

High-Performance Concrete (HPC) is characterized by a lower water-cement ratio which results in lower permeability; however, this can lead to higher autogenous shrinkage.

9.3 Mass Concrete Structures

This section discusses the importance of thermal shrinkage in mass concrete structures and its implications for internal cracking.