Pypropylene Fiber Research Paper

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CHAPTER 3
Project Description
3.1 THEORITICAL CONCEPTS ABOUT FIBER REINFORCED CONCRETE
Concrete being a brittle building material and having low tensile strength is unfit to resist tension until duly reinforced. The concept of using fibers to reinforce building materials is not a nascent concept this method has been old and been run by intuition. Hoarse hairs and straws had been used in old times to prevent plaster material from cracking. More recently when Portland cement started evolving, attempts were made to enhance the properties of the cement by adding fibers. The concept of adding fibers to overcome the inherent behavior of concrete of showing brittle failure under tensile load. After the year 1970 rapid innovation in the field of fiber
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3.1.2 POLYPROPYLENE FIBER IN CONCRETE
Polypropylene fiber is a plastic fiber. Its raw material, derived from the monomeric C3H6 is a pure hydrocarbon similar to paraffin wax. It was suggested by Gold fen that this type of fiber can be used as an admixture to concrete in 1965 during the research for constructing blast resistant building for the U.S. Corps of Engineers. Ready mixed concrete containing polypropylene fibers can be placed using conventional methods. The entrapped air must be expelled in order to ensure maximum performance. Also during the process of incorporating of polypropylene fibers more compaction must be done than for the plain
Concrete. Generally, polypropylene fibers, when mixed with concrete, respond well to conventional compaction techniques and fibers do not easily segregate from the mix.
POLYPROPYLENE FIBER MANUFACTURE:
The commercial production of polypropylene started in 1960s.Two forms of polypropylene fibers started being available one was monofilament and other was film fiber. Extrusion of synthetic polymers into fibers by spinneret was used to produce
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The method requires a slump cone, a standard one-cubic-foot yield bucket and an internal vibrator. The vibrator is started, inserted into the center of the cone, and allowed to fall freely to the yield bucket bottom approximately a few seconds required for total immersion of the vibrator. The vibrator is held vertically with the end of the vibrator just resting on the bottom of the bucket. The time from initial immersion of the vibrator to when the slump mold is empty is recorded as the test time. This test primarily measures the mobility of the mix. Effect of Polypropylene Fibers on Plastic and Drying Shrinkage
Cracking is one of the major problems this is faced during concrete construction. Shrinkage is one of the primary reasons for cracking shrinkage is caused by loss of water.
There can be two types of shrinkage, hardened and plastic. The effects on both are defined below
PLASTIC

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