Natural Fiber-Reinforced Composites in Precast Modular Construction: A Critical Review of Structural Viability and Durability Considerations for High-Rise Applications

Natural Fiber-Reinforced Polymer Composites (NFRPCs), which utilize renewable lignocellulosic fibers, present a compelling, low-carbon alternative. These materials offer substantial environmental benefits. Furthermore, their low density and high specific stiffness (e.g. flax rivaling E-glass on a weight-normalized basis) make them structurally appealing for lightweight, prefabricated elements in high-rise applications. This critical review synthesized contemporary research on integrating NFRPCs into precast modular structures, rigorously assessing their structural viability, material variability, and long-term durability. The analysis confirmed that NFRPCs are immediately viable for high-performance, secondary applications, such as façade cladding and partition systems. In these roles, they exhibit intrinsically beneficial properties, including a very low thermal conductivity (~0.05–0.15 W/m K) and high acoustic absorption (~0.4–0.8), offering superior integrated thermal and acoustic performance compared to traditional inert materials. Durability is challenged by the hygroscopic nature of lignocellulosic fibers, leading to significant moisture absorption, interface weakening, and substantial mechanical degradation, with retained strength potentially dropping to 40–60% of initial values under severe hygrothermal or alkaline exposure. Compounding this, the high inherent variability of natural fibers results in a large coefficient of variation (~0.30–0.40), which necessitates the use of highly conservative material partial safety factors (~1.8–2.2) in reliability-based design, thereby severely limiting the material’s usable load-bearing capacity.