Impact of Combination of Natural and Synthetic Fibers on the Mechanical Properties of Concrete

Abstract

Concrete has found its widespread application as a construction material. The use of different kinds of concrete have revolutionized the construction industry. Concrete as we know is very good in compression, however due to the development of micro cracks under tensile loading in concrete, the tensile strength of concrete is only 1/10th of its compressive strength. This drawback of concrete has been taken care of by the use of reinforcement in concrete. Rebars or reinforcement bars along with the concrete have added much to the tensile strength of concrete. Over the years steel bars, steel fibers and other materials have been used as reinforcement in concrete. Use of reinforcing bars in concrete caters the need of resisting tensile loads and thereby making Reinforced Cement Concrete an excellent construction material. However, the use of heavy steel bars as reinforcement makes concrete structures heavy and difficult to handle. In order to take care of this a new concept of reinforcement has been introduced i.e. reinforcing concrete with fibers. Different types of fibers have been used over the years as reinforcement in concrete. In this experimental study, combinations of two fibers have been used as a reinforcement. One of the fibers is a natural fiber i.e. coconut fiber and other one is a synthetic fiber i.e. polypropylene fiber. Both these fibers are used in combination with a specific percentage. In the first sample 0.5% of recron fiber was used and 0.25% of coconut fiber. In second sample 0.5% recron fiber was used and 0.75% of coconut fiber. The fiber reinforced concrete was then tested for compressive as well as tensile strength. The test results showed 29.4% and 5.3% increase in compressive strength, 32.3% and 48.9% increase in split tensile strength and 40% and 80% increase in the flexural strength of concrete for both combinations respectively. Thus, making the concrete light weight and more resistant to cracking. This could be very useful in case of concrete pavements and slabs.