No abstract

Sisal has been reported as one of the promising fibers for cement composite applications. The durability of sisal fiber reinforced concrete (SFRC) and steel sisal fiber reinforced concrete (SSFRC) have not been reported. Water absorption, rapid chloride permeability, and acid attack tests are conducted on fibrous cement composites. Steel, polypropylene, and sisal fibers with a total volume of 0.50%, 1.00%, 1.25%, and 1.50% were used. Sisal at a content of 1.50% in SFRC increases the water absorption by 76%, but it is reduced to 30% for SSFRC with 0.2% of sisal content. SFRC and SSFRC show the increased permeability of 1.69% and 2.09% respectively. SFRC experiences the highest volume loss of 6.52%. SSFRC illustrates the resistance to the mass loss and compressive strength loss. In conclusion, untreated sisal in any form is found to be not advantageous for durable fibrous concrete structures.

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.

Bond strength between embedded bar and concrete plays vital role in the design of various reinforced concrete structural elements. Use of metallic and synthetic fibres has been shown to be an effective method to enhance tensile strength, reduce shrinkage and improve durability properties of concrete. However, making of synthetic fibres will not only deplete the natural hydrocarbon resources, but also add greenhouse pollutants to the environment. Hence, sisal fibre was considered as a potential alternative to polypropylene fibre. An experimental study was conducted to evaluate the influence of sisal fibres as mono-fibre and in combination with steel as hybrid fibre on bond strength of concrete. The performance of steel polypropylene fibre reinforced concrete (SPFRC) is compared with that of steel sisal fibre reinforced concrete (SSiFRC). Bond strength was conducted onM30 grade concrete for curing periods of 7, 28 and 90 days. Fibre dosages of 0.50%, 1.00%, 1.25% and 1.50% by volume of concrete were used. Results indicated that increase in steel fibre dosage improved the bond strength slightly. However, increase in fibre dosage of either PP fibres or sisal fibres resulted decrease in bond strength. Furthermore, sisal fibre reinforced concrete (SiFRC) showed inferior performance in bond strength as compared to polypropylene fibre reinforced concrete (PFRC). A detailed statistical analysis revealed that although no strong correlation between the compressive strength and the bond strength was evident from the experimental study, means of bond strength of both the hybrid groups did not differ significantly. In addition, empirical equations were proposed to predict the bond strength of fibre reinforced concrete (FRC) based on compressive strength.