Investigation on the Application of Plastic Fibres as Reinforcing Materials In Concrete

Abstract

Reinforcing materials in concrete are employed to enhance the tensile strength because concrete is weak in tension. Existing reinforcing materials have inadequate ductility and inability to reduce concrete cancer (corrosion) which can be addressed by using plastic fibre because of high ductility and inertness. Hence, this research assessed the effect of plastic fibre as reinforcement in concrete. Polyethylene terephthalate materials were obtained from Aradaa Market, Ogbomoso, Nigeria and shredded into fibre size of 65 x 2 mm. The shredded fibre introduced into the concrete mix ratio 1:2:4 using 12 mm aggregate size at 0.5, 1.5 and 2.5% volume fraction of the total mass of the concrete composite. The workability of the concrete produced was assessed in the laboratory through slump test. Plastic fibre reinforced concrete cubes of size 150 x 150 x 150 mm and beams of size 100 x 100 x 500 mm were produced in line with British Standard 882, Part 1 specification. The compressive and flexural strengths of these reinforced concrete composites were examined with the compressive test machine and Universal Testing Machine after 28 days of curing. The crack examination test on plastic fibre reinforced concrete was also done with the use of crack comparator. The slump values varied from 3 – 60 mm height. Compressive strength of the cubes varied from 18.58 to 18.71, 8.18 to 8.22, and 2.22 to 2.27 N/mm for 0.5, 1.5 and 2.5 % volume fraction, respectively. The corresponding flexural strength test values of the beams ranged from 23.95 to 24.01, 12.01 to 12.07 and 4.94 to 5.80 N/mm’, respectively. The crack examination test revealed crack width of 0.05 mm on the plain (0% fibre) concrete cubes while those with fibre reinforcement showed no cracks. Fibres reinforcement at 0.5% volume fraction improved the compressive and flexural strengths and reduced cracks of concrete. Shredded plastic fibres can be successfully used in many construction applications of light weight, non-load bearing and infill panels.