A Comparative Performance of Sisal and Polypropylene Fibres in Enhancing Tensile Strength of Concrete

Abstract

Use of polypropylene (PP) fibres in concrete has been found to be effective in improving various engineering properties of concrete. However, PP fibres cause depletion of natural resources and add pollutants to the greenhouse effect as they are derived from hydrocarbons. Hence, Sisal fibre was considered as an alternate fibre to improve the tensile strength properties of conventional concrete. Manually extracted 12 mm long local sisal fibres were used to evaluate their influence on the tensile strength properties of M30 grade concrete. Fibre dosages of 0.5%, 1.00%, 1.25% and 1.50% of volume of concrete were used. Split tensile and flexural strength of PP Fibre Reinforced Concrete (PFRC) and Sisal Fibre Reinforced Concrete (SFRC) were evaluated for the ages of 7, 28 and 90 days. Linear regression analysis confirmed good correlation between tensile strength properties of PFRC and SFRC. Additionally, scanning electron microscopy (SEM) tests on fractured surface of the specimens were conducted. Presence of PP fibres marginally increased the tensile strength of concrete due to absence of dense hydrated products on the surface of the PP fibres. However, SFRC could not achieve as much strength as PFRC did due to mineralization and migration of hydrated products in SFRC.