Mechanical Characterization of Concrete Reinforced with Sisal Fibers and Expanded Polystyrene Aggregates

• Mercy S. OMEIFE

  Author

• Toyin Y. AKANBI

  Author

• Peace D. PAUL

  Author

Concrete remains the backbone of construction because nothing else carries compressive load as reliably, but two weaknesses persist: it is heavy, and it fails suddenly once its tensile capacity is exceeded. These weaknesses limit its use where a lighter dead load and better crack tolerance matter. This study evaluated the mechanical properties of concrete reinforced with sisal fiber and modified with Expanded Polystyrene (EPS) lightweight aggregate to determine whether a fixed dosage of a cheap, locally available natural fiber could offset the strength lost to EPS substitution. Seven concrete mixes (C0 to C5) were produced at a constant 0.5% sisal fiber dosage while EPS replaced coarse aggregate by volume at 0, 5, 10, 15, 20, and 25%. The fine aggregate was first characterized, returning a fineness modulus of 1.84 and a specific gravity of 2.56, before the mixes were cast and tested for slump, fresh and hardened density, water absorption, and compressive strength at 7, 14, and 28 days. Workability fell from 73 mm (S2 class) in the control mix to 42 mm (S1 class) at 25% EPS replacement, a 42% reduction, while 28-day hardened density declined from 2403 kg/m³ to 1848 kg/m³, a 23.1% reduction that placed the two highest-replacement mixes within the lightweight concrete classification. Water absorption more than doubled, from 2.5% to 5.9%, and 28-day compressive strength dropped from 27.2 MPa to 19.6 MPa, a near-linear loss of about 1.5 MPa for every 5% increment of EPS added. The 0.5% sisal fiber addition produced only minor effects on workability and absorption and did not measurably offset this strength loss at any replacement level tested. Concrete containing 5–10% EPS is therefore recommended for semi-structural, lightly loaded elements, while mixes above 15% EPS are better suited to non-structural applications such as partition panels and insulation blocks.

• 69_Omeife et al. (2026)

Copyright (c) 2026 Mercy S. OMEIFE, Toyin Y. AKANBI, Peace D. PAUL (Author)

This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.