Segregation
Mix proportions, sand grading, sand particle shape, the amount of aggregate fines, the fineness of the cement, water. content of the mix, admixtures, air content, temperature, and depth or thickness of the concrete all influence the rate and total amount of bleeding. Segregation in concrete is a case of particle segregation in concrete applications, in which particulate solids tend to segregate by virtue of differences in the size, density, shape and other properties of particles of which they are composed. Bleeding occurs when the cement and aggregate in newly placed concrete begin to settle and surplus water rises to the top surface of the concrete. Bleeding continues until the cement starts to set, until bridging develops between aggregate particles, or until maximum settlement or consolidation occurs. There are a number of problems which can occur in concrete as a result of improper mixing, placing, or curing. The following are common problems that are easily avoided if proper procedures are followed. Segregation is the tendency of the various constituents of a concrete mix to separate, especially the separation of the large aggregate particles from the cement mortar. For a good concrete mix, aggregates need to be clean, hard, strong particles free of absorbed chemicals or coatings of clay and other fine materials that could cause the deterioration of concrete. Aggregates, which account for 60 to 75 percent of the total volume of concrete, are divided into two distinct categories--fine and coarse. Fine aggregates generally consist of natural sand or crushed stone with most particles passing through a 3/8-inch sieve. Answered by The Community. Making the world better, one answer at a time. Segregation in concrete is a case of particle segregation in concrete applications, in which particulate solids tend to segregate by virtue of differences in the size, density, shape and other properties of particles of which they are composed.
http://theconstructor.org/concrete/avoiding-common-concreting-problems/6691/ https://en.wikipedia.org/wiki/Segregation_in_concrete http://theconstructor.org/concrete/avoiding-common-concreting-problems/6691/ http://theconstructor.org/concrete/avoiding-common-concreting-problems/6691/ http://www.cement.org/cement-concrete-basics/concrete-materials/aggregates http://www.cement.org/cement-concrete-basics/concrete-materials/aggregates http://www.answers.com/Q/What_is_the_segregation_and_bleeding_of_concrete
what causes particle separation in a concrete mix