Abstract

Researchers have been working on formulating Fibre Reinforced Concrete (FRC) composites that are economical, eco-friendly, and waste absorbent. Incorporating agricultural/ industrial waste into the construction industry as fibre-reinforced composites is a novel research field that can recycle and convert waste into valuable supplementary materials. In this study, concrete composites with fibres of coconut coir (COF), wheat straw (WSF), and shredded fibres from waste plastic bottles (PETF) were evaluated and compared against the established use of polypropylene fibres (PPF) and steel fibres (SF). The study’s objectives were set to attain the strength of 32-40MPa (C32/40 European grade) for using these waste fibres as alternatives in FRC. A concrete mix ratio of 1:2:3 with 1-2% waste fibres (COF & PETF), 1-2% PPFC and 10% & 17% steel fibres were used to produce cubes, cylinders, and prisms for testing on 7 and 28 days for evaluation of compressive, split tensile and flexural strengths. Generally, all FRC mixes with 1% fibre dosage exhibited an increase of compressive strength by 9-44% at 28 days of curing. All fibre composites gave characteristic compressive strength of 40-60MPa. The split tensile strength of all-fibre composites was improved up to 48% with 1-2% fibres. The flexural strength of all-fibre composites improved by 11-42% with 1% fibre and 10% steel fibre but increased fibre’s quantity to 2% and steel fibre to 17% reduced the flexural strength suggesting that fibre content should not exceed more than 2% of cement weight in composites. Shredded fibres of PET plastic bottles outperformed the established micro/macro PPF as PETF exhibited better flexural strength than PPF with both 1 and 2% dosages. The natural fibres of coir/ wheat straw gave better/at par flexural strength (7.3MPa) compared to steel fibres (6.9MPa). In conclusion, it is suggested that the optimum quantity of 1-2% of these novel alternative fibres after necessary treatment is feasible for the formulation of environmentally friendly fibre concrete composite with enhanced mechanical properties.

Keywords: Fibre-reinforced concrete; Waste fibres materials; Mechanical properties; Post crack ductility; Empirical modelling