Pineapple leaf conversion to nanocellulose fiber and its impact on the porosity, mechanical strength, and microstructure of cement-based composites

Abstract

The growing demand for sustainable and low-carbon construction materials underscores the importance of developing cementitious composites (CCs) that utilize renewable waste-derived admixtures without sacrificing performance. This study examines the effects of nanocellulose fibers (NF) extracted from pineapple leaf waste– a largely untapped agricultural byproduct–on the mechanical, microstructural, and porosity characteristics of CCs containing Class-F fly ash. CC samples incorporating 0.0–2.0 wt.% NF were evaluated for compressive and flexural strengths, porosity, and microstructural evolution using FTIR, XRD, and SEM analyses. The results revealed that a small addition of 0.5 wt.% NF helped maintain hydration uniformity and retained about 90% of the control compressive strength (74.1 MPa → 66.7 MPa), while higher dosages caused substantial deterioration: compressive and flexural strengths decreased to 10.2 MPa and 2.3 MPa, respectively, corresponding to an approximately 86% reduction in strength and a 253% increase in porosity (10.44% → 36.85%). A strong inverse, nonlinear correlation between porosity and mechanical strength was identified, confirming porosity as the principal factor governing performance. Overall, pineapple leaf–derived NF serves as a promising eco-efficient additive at low concentrations, but excessive dosages lead to agglomeration, hindered hydration, and pore coarsening, emphasizing the need for optimized dispersion and dosage control in bio based fiber–reinforced cement systems. These findings provide insights for the sustainable design of eco efficient CCs.