Natural fiber reinforcement-investigating ramie in cementitious composites with emphasis on fiber surface modifications
Charitha Mudi, Amit Shaw
Abstract
Natural fiber-reinforced cement composites (NFRCCs) are sustainable, cost-effective materials with excellent mechanical performance and environmental benefits. The lignocellulosic fibers are emerging as viable alternatives to synthetic reinforcements like glass. Among the natural fibers, ramie (Boehmeria nivea), known for its high cellulose content and exceptional mechanical properties, remains least explored in cement-based applications despite its success in polymer-based composites. This paper extensively investigates the potential of ramie fibers as reinforcement material in cementitious composites , focusing on the effects of surface modifications, including alkaline treatment (AT) and silane treatment (ST), on composite mechanical performance. Single fiber pullout (SFPO) tests are performed to evaluate the bonding characteristics of untreated and treated ramie fibers . Subsequently, ramie fibers, both untreated and treated, are employed as reinforcements in cement-based matrices at dosages ranging from 0 % to 4 % by volume. The mechanical properties, including tensile and flexural characteristics, of untreated-ramie fiber-reinforced cementitious composite (UTRFRCC), alkaline-treated ramie fiber-reinforced cementitious composite (ATRFRCC), and silane-treated ramie fiber-reinforced cementitious composite (STRFRCC) are compared with polypropylene fiber-reinforced cementitious composite (PPFRCC). SFPO results indicated that alkaline-treated ramie fibers exhibited adhesional shear strength 1.24 and 1.75 times higher than ST and UT ramie fibers, respectively. Composites reinforced with treated-ramie fibers demonstrated enhanced tensile and flexural strength characteristics by approximately 1.25 and 1.92 times compared to UT-ramie, outperforming PPFRCC by 1.34 and 1.6 times, respectively. Notably, treated ramie fibers exhibited better post-peak characteristics compared to UTRFRCC, while ATRFRCC achieved flexural toughness and ductility index closely aligned with 60 % of that of PPFRCC. SEM-EDS observations confirmed that while polypropylene remains almost inert, ramie fibers are found susceptible to moisture absorption . Surface treatments significantly reduced this susceptibility, highlighting their effectiveness and underscoring the potential of treated ramie fibers as sustainable and efficient reinforcement in cementitious composites .