Optimal Polypropylene Fiber Content for Improved Compressive and Flexural Strength of Concrete

Abstract

Worldwide, concrete is a very important construction material, impacting heavily on Gross Domestic Products of many nations: a $30 billion business for ready-mix concrete production industry per year in the United States and a cement consumption rate of about 106kg per person in Nigeria. It is therefore imperative that this important material in the world construction industry must also be endued with the best possible properties. The principles on which reinforced concrete structural designs were based hangs on quality concrete material used in conjunction with quality steel or reinforcing material. However, in Nigeria, the reinforcement steel commonly used is of poor qualities as recent researches have shown that over 40% of 12 mm and 16 mm used within Lagos in 2010 failed the 460N/mm 2 yield strength bench mark of BS8110 of 1997. The employment of micro fibers in the concrete will improve the strength and compensate for the apparently declining strength of Nigerian reinforced concrete building constructions and will also improve the strength of the non-reinforced concrete-sand crate block buildings. This research studies the effects of micro synthetic polypropylene fiber in improving concrete strength with the main focus of identifying the optimal quantity for improved compressive and flexural strengths of concrete. Destructive and non-destructive compressive strength tests and destructive flexural strength tests were carried out on the samples built with 0.25%, 0.5% 0.75% and 1% contents of polypropylene fibers alongside a control samples after 7, 14, 21 28 days of curing. The optimal percentage of polypropylene fiber that produced improved compressive and flexural strengths were found to lie within 0.25% and 0.5%.