Effects of Indigenously Sourced Natural and Hybrid Fibres on Fresh and Hardened Properties of Ultra-High-Performance Concrete
Devesh Ojha¹*, Laxmi Ojha² and Rajendra Kumar Srivastava3
Affiliations
¹ Department of Civil Engineering, Amity University, Lucknow, India
² Military Nursing Service, Indian Army, Lucknow, India
3Retired Engineer in Chief UP P.W.D. and Retired M.D. U.P. Bridge Corporation, Lucknow, India
Corresponding Author
Devesh Ojha
Department of Civil Engineering
Amity University, Lucknow, India
E-mail: dojha@lko.amity.edu
ORCID: 0000-0003-2814-9555
Abstract: The effect of indigenously sourced natural fibres jute, sisal, basalt, and nylon and their binary combinations with high-carbon steel microfibres on the fresh and hardened properties of commercial ultra-high-performance concrete (UHPC) was investigated in the Indian construction context. Six fibre types, added at 1% and 2% by volume, and five binary combinations at a total of 2% fibre content, were evaluated for flowability, compressive strength, flexural performance, toughness, bulk resistivity, and density. Jute (JF) and sisal (SF) fibres, treated with 5% NaOH solution to improve fibre-matrix adhesion, were the primary focus as cost-effective and domestically available alternatives to high-carbon steel. Results indicate that NaOH-treated jute fibres at 2% addition achieved flexural strength of 20.1 MPa, comparable to the 20.8 MPa of the steel control mixture (CS2). Binary combinations of steel-jute (CS1JF1) and steel-sisal (CS1SF1) demonstrated synergistic flexural behaviour, achieving 24.1 MPa and 23.5 MPa respectively, representing increases of 9–16% over single-fibre equivalents at the same total dosage. Sisal fibres significantly reduced flowability due to their high aspect ratio and hydrophilic surface chemistry, analogous to polyethylene fibres in prior studies. Jute-basalt binary mixes exhibited a cost per flexural unit 26% lower than the steel control, making them particularly relevant for bridge repair and pavement overlay applications in Indian infrastructure. Clearly, there are trade-offs among cost, flowability, flexural strength, and compressive strength that can be leveraged through informed fibre selection.
Keywords: Ultra-high-performance concrete · Natural fibres · Jute · Sisal · Basalt · Hybrid fibre systems · India · Flexural toughness
