Special Types of Concrete

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Discription on Ready Mix Concrete, Vacuum Concrete,Shortcrete,Ferrocement,Light Weight Concrete,Air Entrained Concrete, Fiber Reinforced Concrete,Polymer Concrete.
Unit 5, according to Rajiv Gandhi Technological University syllabus.

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Special Types of Concrete

  1. 1. Rishabh Lala VI SEM Rajiv Gandhi Technological University,Bhopal
  2. 2. The following are the concrete that we are going to discuss in this chapter: Ready Mix Vacuum Concrete Shortcrete Ferrocement Fiber Reinforced Concrete Polymer Concrete Light weight concrete Air Entrained Concrete
  3. 3. Ready-mix concrete is concrete that is manufactured in a factory or batching plant, according to a set recipe, and then delivered to a work site, by truck mounted in–transit mixers. This results in a precise mixture, allowing specialty concrete mixtures to be developed and implemented on construction sites. The first ready-mix factory was built in the 1930s, but the industry did not begin to expand significantly until the 1980s, and it has continued to grow since then.
  4. 4. Vacuum concrete, made by using steam to produce a vacuum inside a concrete mixing truck to release air bubbles inside the concrete, is being researched. The idea is that the steam displaces the air normally over the concrete. When the steam condenses into water it will create a low pressure over the concrete that will pull air from the concrete. This will make the concrete stronger due to there being less air in the mixture. A drawback is that the mixing has to be done in a mostly airtight container.
  5. 5. Shotcrete refers to the type that utilizes compressed air in order to shoot concrete towards a finished frame or structure. This type of concrete is preferred for works that are needed to be applied overhead or on vertical surfaces. This is used for repairs on bridges, dams, pools and other application that needs the concrete to be applied without forming. Shotcrete eliminates the use of formwork for its application.
  6. 6. The term ferrocement, also referred to as ferro concrete or reinforced concrete, is most commonly applied to a mixture of Portland cement and sand applied over layers of woven or expanded steel mesh and closely spaced small-diameter steel rods rebar. It can be used to form relatively thin, compound curved sheets to make hulls for boats, shell roofs, water tanks, etc. It has been used in a wide range of other applications including sculpture and prefabricated building components. The term has been applied by extension to othercomposite materials including some containing no cement and no ferrous material. These are better referred to by terms describing their actual contents.
  7. 7. Fiber-reinforced concrete (FRC) is concrete containing fibrous material which increases its structural integrity. It contains short discrete fibers that are uniformly distributed and randomly oriented. Fibers include steel fibers, glass fibers, synthetic fibers and natural fibers – each of which lend varying properties to the concrete. In addition, the character of fiber-reinforced concrete changes with varying concretes, fiber materials, geometries, distribution, orientation, and densities.
  8. 8. Polymer concrete is part of group of concretes that use polymers to supplement or replace cement as a binder. The types include polymerimpregnated concrete, polymer concrete, and polymer-Portlandcement concrete. Polymers in concrete have been overseen by Committee 548 of the American Concrete Institute since 1971
  9. 9. b. Air Entrained Concrete The concrete prepared by mixing aluminum in it is called air entrained, cellular or aerated concrete. In this concrete bubbles of hydrogen gas are liberated which forms cell and make the concrete cellular. USES: This concrete is used for lining walls and roofs for heat and sound insulation purpose.
  10. 10. c. Light Weight Concrete The concrete prepared by using coke breeze, cinder or slag as coarse aggregate is called light weight concrete. The concrete is light in weight and posses heat insulating properties. USES This concrete is used in making precast structural units for partition and wall lining.

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