What Is Concrete Creep

Definition: time-dependent deformation due to sustained load.- ACI Concrete Terminology. Creep is indicated when strain in a solid increases with time while the stress producing the strain is kept constant.

What causes creep in concrete?

The creep originates in the calcium silicate hydrates (C-S-H) of hardened Portland cement paste. It is caused by slips due to bond ruptures, with bond restorations at adjacent sites. The C-S-H is strongly hydrophilic, and has a colloidal microstructure disordered from a few nanometers up.

What is basic creep of concrete?

Concrete creep is defined as: deformation of structure under sustained load. Basically, long term pressure or stress on concrete can make it change shape. This deformation usually occurs in the direction the force is being applied. Like a concrete column getting more compressed, or a beam bending.

What is shrinkage and creep of concrete?

Drying shrinkage (often, simply shrinkage) is the reduction in the volume of hardened concrete due to loss of moisture by evaporation. In shrinkage, the loss is due to difference in the relative humidity of concrete and the environment, in creep it is due to sustained applied stress.

What is creep and which factors affect creep?

These two types of curing reduce the drying shrinkage by half as much as they reduce creep. Other factors affecting creep include type of cement, amount of cement paste, size and shape of concrete, amount of reinforcement (rebar), volume-to-surface ratio, temperature, and humidity.

Is creep harmful or beneficial?

The effects of creep may thus be harmful. On the whole, however, creep unlike shrinkage is beneficial in relieving stress concentrations and has contributed to the success of concrete as a structural material.

What is creep effect?

In materials science, creep (sometimes called cold flow) is the tendency of a solid material to move slowly or deform permanently under the influence of persistent mechanical stresses. It can occur as a result of long-term exposure to high levels of stress that are still below the yield strength of the material.

What is the advantage of creep?

Creep plays an important role on the cracking resistance of concrete because it can relieve the stress and help to reduce the cracking potential of the concrete structure at the early age [1, 2].

How is concrete creep measured?

Usually creep is determined by measuring the change with time in the strain of a specimen of concrete subjected to a constant stress and stored under appropriate conditions. A typical testing device is shown in Fig. 15.18. Under compressive stress the creep measurement is associated with shrinkage of concrete.

What are the 4 main properties of concrete?

The properties of hardened concrete Mechanical strength, in particular compressive strength. The strength of normal concrete varies between 25 and 40 MPa. Durability. Porosity and density. Fire resistance. Thermal and acoustic insulation properties. Impact resistance.

What is difference between creep and shrinkage?

What is the difference between creep and shrinkage? When concrete is subjected to compressive loading it deforms instantaneously. This time-dependent strain is termed as creep. Drying shrinkage (often, simply shrinkage) is the reduction in volume of hardened concrete due to loss of moisture by evaporation.

How do you reduce concrete shrinkage?

How to Reduce Shrinkage of Concrete at Construction Site? Reduce Water Quantity. Add Additives. Aggregate. Protect Concrete Surface from Rapid Drying. Time of Concreting. Proper Concrete Compaction. Proper Curing. Adequate Contraction Joints and Steel Detailing.

What are the types of shrinkage?

The paper explains the basic types of shrinkage: carbonation shrinkage, plastic shrinkage, temperature shrinkage, chemical shrinkage, autogenous shrinkage, and drying shrinkage.

What is creep failure?

Creep may be defined as a time-dependent deformation at elevated temperature and constant stress. It follows, then, that a failure from such a condition is referred to as a creep failure or, occasionally, a stress rupture. The temperature at which creep begins depends on the alloy composition.

How do you reduce creep?

In general, there are three general ways to prevent creep in metal. One way is to use higher melting point metals, the second way is to use materials with greater grain size and the third way is to use alloying. Body-centered cubic (BCC) metals are less creep resistant in high temperatures.

What are the effects of creep in rails?

Creep of rails often results in uneven size of gap between railway track and even rail dislocation in severe cases. At the same time, the sleeper will also occur skew phenomenon, which will cause great damage to the line, resulting in poor rail structure and endangering traffic safety.

What is concrete workability?

Workability of Concrete is a broad and subjective term describing how easily freshly mixed concrete can be mixed, placed, consolidated, and finished with minimal loss of homogeneity.

What are the 3 stages of creep?

Primary Creep: starts at a rapid rate and slows with time. Secondary Creep: has a relatively uniform rate. Tertiary Creep: has an accelerated creep rate and terminates when the material breaks or ruptures. It is associated with both necking and formation of grain boundary voids.

What is creep and example?

The definition of a creep is the act of moving slowly or is slang for a scary or odd person who is unpleasant or repulsive. An example of a creep is a hill that is moving very slowly. An example of a creep is a scary, leering old man who always stares at you when you walk by his house.

Is creep elastic or plastic?

1.1 Definition of creep In general, creep refers to the time-dependent component of plastic deformation. This means that creep is a slow and continuous plastic deformation of materials over extended periods under load.

What is creep in civil engineering?

Creep is a term used in materials science and civil and mechanical engineering. It describes the time-dependent behaviour of a solid which, when subjected to continuous stress deforms permanently below its yield point (the limit of elastic behaviour after which loads applied will cause permanent deformation.)Jan 26, 2021.

What is the effect of creep in reinforced concrete columns?

A concrete element when kept under sustained load presents progressive strain over time, associated to the creep. In reinforced concrete columns, such deformations cause the stress increase in the steel bars of the reinforcement and may induce the material to undergo the yielding phenomenon.

What is autogenous shrinkage?

Autogenous shrinkage is defined as the macroscopic volume change due to the capillary pressure induced by self-desiccation and chemical process of cement hydration, without water transferring to the surrounding environment [4].

What is the light weight concrete?

Lightweight concrete is a mixture made with lightweight coarse aggregates such as shale, clay, or slate, which give it its characteristic low density. It is being increasingly used to build sleek foundations, and has emerged as a viable alternative to regular concrete.