Durable and sustainable nano-modified basalt fiber-reinforced composites for elevated temperature applications

This study investigates the performance of nano-modified basalt fiber pellet reinforced cementitious composites (NBFRCC) exposed to elevated temperatures. The composite mixtures have been reinforced with basalt fiber pellet (BFP) coated with a polymeric resin and incorporated cement, slag, nano-silica (Ns) and/or nanofibrillated cellulose (NFC). In total, nine mixtures have been prepared by altering the dosages of BFP (2.5% and 4.5%), Ns (6%) and NFC (0.5%). The mechanical properties like compressive and flexural stress have been explored. The samples are exposed to elevated temperatures of 200°C and 600°C and chloride. Microstructural analysis is also done by SEM and EDX analysis. For most of the mixes, 600˚C exposure for 60 minutes showed up to 15% higher compressive strength than 200˚C, attributed to high percentage of slag (40%). Maximum flexural stress is obtained for 2.5% BFP mixed with both Ns and NFC after 600˚C exposure. The exceptionally high melting point of BFP aids in maintaining higher flexural stress at high temperatures. Nano-modified mixtures show slower declines in flexural stress from room temperature to 600°C, indicating improved mechanical properties and thermal stability. NFC-mixed samples showed the least reduction in flexural strength at 600°C than at 200°C, ranging between 8-10%. Chloride ion penetrability is also reduced from low to very low penetrability class. Performance index (PI) considering mechanical strength, durability, and cost shows that 2.5% BFP with Ns is optimal for sustainable applications. This research will expand the application of NBFRCC, providing a cost-effective and environmentally friendly approach to contemporary construction problems where improved fire resistance and durability are fundamental. • Nano-modified basalt fiber pellet-reinforced composites (NBFRCC) exhibit enhanced mechanical properties and thermal stability at elevated temperatures. • Exposure to 600°C resulted in minimal strength degradation, with some mixtures showing improved compressive strength due to slag-induced tobermorite formation. • Flexural stress retention was highest for mixtures with 2.5% basalt fiber pellets, nano-silica, and nanofibrillated cellulose, ensuring better fire resistance. • Chloride ion penetrability was significantly reduced in nano-silica-based composites, improving long-term durability. • The optimal mix design balances mechanical strength, durability, and cost, making NBFRCC a promising material for fire-resistant and sustainable construction.