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 min 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 and 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.