0
Concrete naturally shrinks as it cures. If the pour is large enough, cracks WILL occur. Structural designers introduce so-called "control joints" in large pours so that cracking either does not occur, or occurs in predictable areas. If you look at a typical concrete driveway for instance, you will notice lines scored across the concrete every few feet. Any stress cracks that occur are more likely to happen in the joint, where they will be less noticeable. This can be a huge problem in certain structures such as dams or the containment building at a nuclear power plant. Concrete for these types of structures has to be carefully engineered and layed. Concrete gives off heat as it cures (an 'exothermic' chemical reaction) and this can make the problem much worse. It is common to mix the concrete for a dam with chilled water and pour it in many thin layers to minimize creep and shrinkage caused cracks and flaws.
What else can I help you with?
Shrinkage of concrete?
The loss of water results in reduction of volume of concrete this is known as shrinkage of concrete.Prevention of shrinkage in concrete:Low moisture contentSize of aggregates used.
What is the influence of calcium stearate on the shrinkage of concrete?
Calcium stearate is used to control effloresence in concrete. I don't believe there is any effect on shrinkage. However, it is often added to other concrete admixtures, like water reducers. Those products can effect shrinkage, but usually they help to reduce it.
What are the types of shrinkage in concrete?
the amount u put aw aw yea lick
What does shrinkage temperature steel do?
Steel bars laid in concrete to reduce cracking do to temperature change
How does fineness modulus of aggregates affect the strength of concrete?
how does the fineness modulus of aggregate affect the strength of concrete
What has the author Perry H Petersen written?
Perry H. Petersen has written: 'Shrinkage and creep in prestressed concrete'
Shrinkage of concrete?
The loss of water results in reduction of volume of concrete this is known as shrinkage of concrete.Prevention of shrinkage in concrete:Low moisture contentSize of aggregates used.
What is creep in concrete?
Creep is what happens when concrete changes form because of pressure or load on the concrete. It can occur immediately or long term.
Does the modulus of elasticity affects the durability of fresh concrete?
Factors Influencing CreepConcrete that exhibits high shrinkage generally also shows a high creep, but how the two phenomena are connected is still not understood. Evidence suggests that they are closely related. When hydrated cement is completely dried, little or no creep occurs; for a given concrete the lower the relative humidity, the higher the creep.Strength of concrete has a considerable influence on creep and within a wide range creep is inversely proportional to the strength of concrete at the time of application of load. From this it follows that creep is closely related to the water-cement ratio. There is no doubt also that the modulus of elasticity of aggregate controls the amount of creep that can be realized and concretes made with different aggregates exhibit creep of varying magnitudes.Experiments have shown that creep continues for a very long time; detectable changes have been found after as long as 30 years. The rate decreases continuously, however, and it is generally assumed that creep tends to a limiting value. It has been estimated that 75 per cent of 20-year creep occurs during the first year.Effects of CreepCreep of plain concrete does not by itself affect strength, although under very high stresses creep hastens the approach of the limiting strain at which failure takes place. The influence of creep on the ultimate strength of a simply supported, reinforced concrete beam subjected to a sustained load is insignificant, but deflection increases considerably and may in many cases be a critical consideration in design. Another instance of the adverse effects of creep is its influence on the stability of the structure through increase in deformation and consequent transfer of load to other components. Thus, even when creep does not affect the ultimate strength of the component in which it takes place, its effect may be extremely serious as far as the performance of the structure as a whole is concerned.The loss of prestress due to creep is well known and accounted for the failure of all early attempts at prestressing. Only with the introduction of high tensile steel did prestressing become a successful operation. 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 a shrinkage joint?
A shrinkage joint, or control joint is a separation cut with a finishing handtool into wet concrete sidewalks to 1/4 of the depth of the concrete. Since concrete shrinks a tiny bit as it cures, little tiny cracks may develop . . . the shrinkage joints make those cracks appear in the nice straight joints, thus improving the looks of the new concrete walk. Shrinkage joints may also be cut in after the concrete has cured long enough to stand on (several hours) with a concrete-cutting saw.
What is the influence of calcium stearate on the shrinkage of concrete?
Calcium stearate is used to control effloresence in concrete. I don't believe there is any effect on shrinkage. However, it is often added to other concrete admixtures, like water reducers. Those products can effect shrinkage, but usually they help to reduce it.
What is the creep in 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. Creep does not necessarily cause concrete to fail or break apart. Creep is factored in when concrete structures are designed.
Why shirinkage in concerete?
Shrinkage in concrete occurs due to the loss of moisture during the curing process. As the water evaporates, the concrete material contracts and reduces in volume. This shrinkage can lead to cracks forming in the concrete if not properly controlled. Factors such as mix design, curing methods, and environmental conditions can influence the extent of shrinkage in concrete.
What has the author Edward M Wallo written?
Edward M. Wallo has written: 'Prediction of creep in structural concrete' -- subject(s): Concrete, Creep, Expansion and contraction
What are the types of shrinkage in concrete?
the amount u put aw aw yea lick
What does shrinkage temperature steel do?
Steel bars laid in concrete to reduce cracking do to temperature change
Difference between type k cement and cement fondue?
Type K cement is slightly expansive and helps reduce the shrinkage issues associated with normal cement in concrete mixes. Cement fondu is an accelerated cement that provide concrete higher earlier strength. It does not specifically compensate for shrinkage
