Segregation in concrete is a case of

particle segregation In particle segregation, particulate solids, and also quasi-solids such as foams, tend to segregate by virtue of differences in the size, and also physical properties such as volume, density, shape and other properties of particles of which they ...

concrete Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most wid ...

applications, in which particulate

solid Solid is one of the four fundamental states of matter (the others being liquid, gas, and plasma). The molecules in a solid are closely packed together and contain the least amount of kinetic energy. A solid is characterized by structural ...

s tend to segregate by virtue of differences in the size,

density Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' can also be used. Mathematical ...

, shape and other properties of particles of which they are composed. Ségrégation béton

Definition

It is described by

American Society for Testing and Materials ASTM International, formerly known as American Society for Testing and Materials, is an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, an ...

as follows: "Segregation in concrete is commonly thought of as separation of some size groups of aggregates from cement mortar in isolated locations with corresponding deficiencies of these materials in other locations. Segregation results in proportions of the laid concrete being in variation with those designed. Segregation could result from internal factors such as concrete that is not proportioned properly and not mixed adequately, or too workable a mix. It also could result from external factors such as too much vibration, improper transportation, placement, or adverse weather conditions. The corresponding increase in proportion of

cement A cement is a binder, a chemical substance used for construction that sets, hardens, and adheres to other materials to bind them together. Cement is seldom used on its own, but rather to bind sand and gravel ( aggregate) together. Cement mi ...

paste in upper areas would tend to make them susceptible to increased shrinkage and formation of cracks. These cracks could be 10 µm to 500 µm wide, formed perpendicular to the surface, and be in the form of map patterns." The concrete should be free from segregation. It is defined as the breaking up of cohesion (separation of concrete aggregate) in a mass of concrete. It results in honey-combing, decrease in density, and ultimately loss of strength of hardened concrete. The effect of aggregate segregation on the mechanical and transport behavior of concrete has been the focus of both modeling as well as experimental investigation.

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References

External links

- from Civil Experiences
Lecture 12: Module 5 Lecture - 4 Fresh Concrete : Segregation & Bleeding
from the Indian Institute of Technology, Delhi Concrete {{Civil-engineering-stub

Definition

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