Creep of Concrete

By Mukul Yadav|Updated : December 7th, 2022

In concrete structures, as time passes, some permanent deformation has been observed in the different parts of the concrete structures. This permanent deformation is called the creep of concrete. Creep of concrete structures occurs over a long time due to the sustained loading over the years on a structure.

Creep of Concrete PDF [GATE Notes]

Creep will not occur due to the effect of live load over the structure; this deformation is called elastic or plastic deformation. The creep of concrete structures should lie within its permissible limit of deformation. If it exceeds the limit, the structure will not be used further. In this article, the creep of concrete will be covered in all aspects with detailed information.

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Table of Content

What is Creep of Concrete?

Creep of concrete is the permanent deformation reported in a part of a structure due to the sustained load for a long time. Creep indicates that strain in the structure continuously increases, but stress remains constant. Creep in a structure will depend on the structural material, loading quantity, loading duration, etc. Creep in concrete structures will be lesser than in steel structures.

Creep deformation generally occurs in 3 stages. These stages are called primary creep, secondary creep and tertiary creep. In the primary stage, concrete creep starts rapidly, and the rate decreases with time. In the secondary stage, creep generally occurs at a constant rate. And in the tertiary stage, creep starts at an increasing rate until the structural member breaks down.

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Factors Affecting Creep of Concrete

As we discussed, creep is the permanent deformation caused by sustained loading. So based on the cause of the creep of concrete, it will depend on several factors. These factors govern the quality of the concrete material. These factors include the time depending loading factors and parameters related to manufacturing concrete material. Here a few factors are listed below on which the creep of concrete depends.

  • Type of cement used for the construction of concrete material
  • Quantity of cement used in the concrete
  • Size and shape of the concrete material
  • Amount of the reinforcing bars
  • Surface-to-volume ratio
  • The humidity of the surrounding atmosphere
  • The temperature of the surrounding atmosphere

These above-mentioned factors also govern the overall strength of the concrete material.

Creep of Concrete Formula

The formula for the creep of concrete depends on several factors, including the creep coefficient and loading factors. Creep is the deformation induced in the structural member; hence it can be calculated by the following formula.

Creep of concrete = creep strain × length of the member.

Creep strain can be related to the modulus of elasticity of concrete at the age of the concrete.

The modulus of elasticity at a particular age of the concrete can be calculated as Ec=Es/(1+Θ)

Where Θ is the creep coefficient, which will depend on the age of the concrete.

Creep of Concrete Formula

Loss of Prestress Due to Creep of Concrete

In the case of prestressing, some amount of prestressing loss will occur due to concrete creep. The following parameters can obtain it. Loss of prestress due to the creep of the concrete is the product of ultimate creep strain and the modulus of elasticity of steel at the level of prestressing steel.

Other types of losses occur in prestressed concrete:

  • Shrinkage of concrete
  • Elastic shortening
  • Frictional loss
  • Creep of concrete
  • Relaxation of steel
  • Anchorage slip

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Difference Between Shrinkage and Creep of Concrete

Shrinkage and creep of concrete both the deformation of the concrete due to the sustained loading.

Creep is the permanent deformation of the concrete material caused by sustained loading over the concrete structures. The creep of concrete depends on the age of the concrete. As the age of the concrete increases, the creep of the concrete increase with the decreasing rate.

Due to the shrinkage effect of the concrete, it will either shrink or expand gradually. Shrinkage of the concrete occurs when some entrapped air exceeds out, or swelling of the concrete material occurs by any means.

Other Important GATE Notes
SteelZero Force Member In A Truss
Functions Of The Network LayerTransverse Loading
Geometric Design Of HighwaysMoment Area Method
Macaulays MethodImpact Load
Impulse An MomentumUniformly Varying Load


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Creep of Concrete FAQs

  • The creep of concrete is the time-dependent deformation of the concrete. It will occur due to sustained loading over the years. The creep of the concrete will not be observed in a short span of time.

  • The creep of concrete depends on several factors, including the age of the concrete, admixtures used, type of cement and other factors. As the age of concrete increases, the creep coefficients of the concrete decrease; hence the overall rate of creep decreases.

  • Shrinkage of the concrete is the short-term deformation of the concrete. It will occur when the entrapped air is expelled out, or swelling occurs for any reason. Due to the expulsion of the air, shrinkage of concrete occurs, and the volume reduces of the concrete material.

  • The creep coefficient is the coefficient on which the creep of concrete depends. The creep coefficient's value decreases as the concrete age increases. The creep of concrete depends on the creep coefficient. As the age increases creep coefficient decreases.

  • Shrinkage and creep of concrete are the amount of deformation but creep in concrete is the long-term deformation, and shrinkage is the short-term deformation of the concrete. Shrinkage occurs due to the expulsion of air, but creep occurs due to the rearrangement of the particles as time passes.

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