Concrete Creep problems are serious from point of view of serviceability problems, stress redistribution, prestress loss, and even failure of structural elements but most people ignore the effects of creep in concrete.
So Civil Experience discusses all information related to What is Creep in Concrete (Concrete Creep) – Types, Factors, Effects, Which of the following factors influences the creep of concrete? | Types of Creep in Concrete | Factors Affecting Creep in Concrete technology | What Are The Effects of Creep in Concrete
Join us before you get lost in reading what is creep in civil engineering useful information so that you can read our every information, useful article of Civil Experience.
Creep in Concrete
Definition of Creep in Concrete
First of all look at what is Definition of Creep in Concrete (Creep Definition in Civil Engineering) is, the meaning of creep means creep in concrete definition. We can define creep in concrete in this way:
Escalation of stress in cement concrete over time under constant (stable) stress is called creep.
In sort deformation of concrete structure under continuous load. under continuous load, For a long duration, the concrete readjusts themselves, which behavior is called creep.
The shrinkage of concrete and creep of concrete occurs at the same time and they are assumed to be additive for simplicity.
What is Creep Recovery?
When the sample element is free from load the immediate recovery or elastic recovery is followed by a gradual decrease in strain known as creep recovery.
Although creep recovery is much faster compared to creep, the creep strain is not the opposite total.
Mechanism of Creep in Concrete
The reversal of creep is not fully 100% complete, and creep is not a simply reversible phenomenon, so Continuous use of load, even only over a period of a day, results in a residual deformation or permanent deformation or irreversible creep. Creep in concrete pictures see below.
 |
| Creep in Concrete https://creativecommons.org/licenses/by-sa/4.0/ |
What is Creep Relaxation?
If a loaded cement concrete sample is viewed as being subjected to a continuous strain, the creep decreases the stress progressively with time duration. This is known as relaxation.
Creep in Concrete is also known as
Creep in concrete is also known as plastic flow, plastic yield, or plastic deformation.
Creep Function
Creep is a function of time
The creep proportions may be due to the viscous flow of cement paste/slurry due to the closing of the internal voids and the overall crystalline flow.
But it is conceded that a large portion is produced by the seepage of colloidal water from the gel formed during the hydration process of cement.
The rate of getting rid of the colloidal water is a function of the applied compressive force and of the friction in the capillary channels.
If the force is greater, the sleeper the pressure gradient, with a resulting increase in the rate of emitting moisture and deformation.
Types of Creep in Concrete
Generally, Types of Creep in Civil Engineering are mentioned below with short notes.
- Basic creep
- Drying creep
- Specific creep
Basic creep
Application of constant stress on a concrete specimen under conditions of 100 percent relative humidity, leads to an increase of strain over time, which is called basic creep
Drying creep
The additional creep that occurs when the specimen under load is also drying is called drying creep
Specific creep
Creep strain per unit of the applied stress is called specific creep
Creep coefficient
It is the ratio of ultimate creep strain to elastic strain
Creep occurs due to
- Internal movement of absorbed water
- Moisture loss
- Sliding between gel particles
- Growth in microcracks
Factors Affecting Creep in Concrete
Which of the following factors influences the creep of concrete?
Read this article clearly so that you also learn how to reduce creep in concrete structures. because if you clearly learn and understand what are Factors Affecting Creep in Concrete, which are the reason for concrete creep then you also alternative learn how to reduce creep in concrete.
Also same answer for what causes creep in concrete.
The magnitude of creep depends upon the following factors
- Aggregate
- Water/cement ratio
- Age at the time of loading
- The moisture content of the concrete
- The humidity of the ambient air
- Type of cement
- Intensity and duration of stress
- Size of the specimen
- Temperature
Aggregate
- Normally, aggregate undergoes very little creep. It is the paste that is responsible for the creep. However, the aggregate provides a restraining effect, when the paste undergoes creep. The stronger the aggregate, the more is the restraining effect and hence the less is the magnitude of creep
- The modulus of elasticity of aggregate is also one of the important factors influencing creep. The higher the modulus of elasticity of aggregate, the fewer creeps.
- Lightweight aggregate shows considerably higher creep than normal-weight aggregate, because of lower modulus of elasticity
- It has been found that the greater the maximum size of an aggregate, the less is the creep of Concrete
Water/Cement Ratio
- A higher water/cement ratio increases the size of the pores in the paste structure. The amount of paste content and the quality of the mix design is one of the most important factors influencing creep
- A poor paste structure undergoes higher creep
- Creep increases with an increase in water/cement ratio
- All the factors which are affecting the water/cement ratio, also affect the creep of concrete
Age at the time of loading
- The quality of gel improves with time. Such gel creeps less, whereas a young gel under load being not so stronger creep more. hence, creep decreases with the age of concrete
| Age of concrete | Creep |
| After 1 year | 1.0 |
| After 2 year | 1.14 |
| After 5 year | 1.20 |
| After 10 year | 1.26 |
| After 20 year | 1.33 |
| After 30 year | 1.36 |
Moisture Content of Concrete
- An increase in the moisture content of concrete, increases creep
Humidity or Ambient Air
- The humidity of the air affects the seepage of moisture from the concrete. An increase in the humidity reduces the rate of loss of moisture and this reduces the seepage. Thus for a given concrete creep is higher
- The lower the relative humidity. Drying of the concrete while under load enhances creep of concrete
Effect of Type of Cement in Creep
- The type of cement influences creeps in so far it influences the strength of the concrete at the time of application of the load. Under drying conditions, Portland blast-furnace slag cement results in a higher creep than usual types of Portland cement
- Finess of cement affects strength development at early ages and thus influences creep. The finer the cement the higher its gypsum requirement, so that re-girding a cement in the laboratory without the addition of gypsum produces improperly regarded cement, which exhibits high creep
Intensity and Duration of Stress
- In many tests, a direct proportionality between creep and the applied stress has been found to exist.
- Troxelletal found that specimens cured for 90 days and then loaded for 21 years showed 680, 1000, and 14.0 * 10^(-6) creep strains, corresponding to sustained stress levels of 4 MPa, 6 MPa, and 8 MPa respectively
Size of Specimen
- The size of the specimen also affects the magnitude of creep
- The magnitude of creep decreases with an increase in the Size of the specimen
- This is due to the reduced seepage as the path travelled by the expelled water is greater with a resulting increase in the frictional resistance to the flow of water from the interior
Temperature
- The temperature to which concrete is exposed can have two counteracting effects on creep
- If a concrete member is exposed to a higher than normal temperature as a part of the curing process before it is loaded, the strength will increase and the creep strain would be less than that of a corresponding concrete stored at a lower temperature
- On the other hand, exposure to high temperatures during the period under load can increase creep. The influence of temperature on creep is of considerable interest to nuclear Prestressed Concrete Reactor Vessel (PCRV)
Effects of Creep | What Are The Effects of Creep in Concrete
What Are The Effects of Creep in Concrete is the key target to learn and know about concrete creep comes in engineer's minds.
Civil Experience Civil engineering blog make a brief list of What Are The Effects of Creep in Concrete which is described below
- In reinforced concrete beams, creep increases the deflection with time and maybe a critical consideration in the design.
-
In reinforced concrete columns creep results in a gradual transfer of load from the concrete to the reinforcement
- The extra load in steel is required to be shared by concrete and this situation results in the development of full strength of both steel and concrete. This way creep property is useful in reinforced concrete columns
- However, in eccentrically loaded columns, creep increases the deflection and can lead to buckling
- In statically indeterminate structures, creep may relieve stress concentrations induced by shrinkage, temperature changes, or settlement of supports. In all concrete structures creep reduces internal stresses due to non-uniform load or restrained shrinkage
-
In mass concrete, creep in itself may be a cause of cracking when restrained concrete mass undergoes a cycle of temperature change due to the development of the heat of hydration and subsequent cooling
- Therefore, all precautions and steps must be taken to see that increase in temperature does not take place in the interior of mass concrete structures like concrete dams, retaining walls, etc.
- The rise in the temperature in the interior of a large concrete mass must be controlled by the use of low heat cement, a low cement content, precooling of mix design ingredients, limiting the height of concrete lifts, and cooling of concrete by circulating refrigerated water through a network of pipes embedded in the concrete mass
- In the case of prestressed concrete, creep reduces prestress and provision is the mage for the loss of prestress in the design of such structures
Above all are examples of effects of creep in concrete if you think we forget some then write in the comment box.
How to Prevent Creep in Concrete
How to reduce creep in concrete or how to prevent creep in concrete is a simple and short guide which are given below:
- Use better design to reduce the possible factors of creep.
- Use materials with greater grain size.
- By using alloy.
- Use higher metals.
Creep in Concrete MCQ
Creep in concrete structure increases with MCQ
ANSWER = [D] Decrease in humidity
The correct answer for Creep in concrete structure increases with Decrease in humidity.
Solution(By Civil Experience Team)
Creep is small deformation that formed due to concrete loading which is caused due to increase in temperature and decrease in humidity
Creep strains in concrete structure are usually ______
The correct answer for Creep strains in concrete structures is usually is [D] caused by sustained loads.
If you gain valuable solutions from Civil Experience then must follow us for the latest updates & important materials/solutions.
Help your friends by sharing this article. Also, share your idea/problem/Suggestion in the comments box.
FAQ 1: What is the Definition of Creep in Concrete?
Creep Definition in Civil Engineering is Escalation of stress in cement concrete over time under constant (stable) stress is called creep.
FAQ 2: What is Creep in Concrete?
Deformation of concrete structure under continuous load. under continuous load, For a long duration, the concrete readjusts themselves, which behavior is called creep.
FAQ 3: Types of Creep in Concrete?
Generally, Types of Creep in Civil Engineering are mentioned below with short notes.
- Basic creep
- Drying creep
- Specific creep
FAQ 4: What are the Factors Affecting Creep of Concrete?
Which of the following factors influences the creep of concrete?The magnitude of creep depends upon the following factors
- Aggregate
- Water/cement ratio
- Age at the time of loading
- The moisture content of the concrete
- The humidity of the ambient air
- Type of cement
- Intensity and duration of stress
- Size of the specimen
- Temperature
