Effect of elevated temperature on the micro-structure and pore size distribution of sustainable bio-fiber-reinforced ultra-high toughness cementitious composites

The demand for sustainable construction methodology is a need of the hour, as the material used in construction activities also greatly contributes to environmental emissions. Although conventional engineered cementitious composites (ECC) could greatly enhance the strength of composite materials by incorporating fibers, synthetic fibers, and cement production emits a great deal of carbon dioxide into the atmosphere. The work attempts to report a detailed thermal study on the performance of natural fiber-reinforced ultra-high toughness cementitious composites (UHTCC). Test parameters include temperature levels (300 degrees C, 600 degrees C and 900 degrees C), type of natural fiber (flax and hemp), and fiber volume fraction (Vf =2% and 3%). Moreover, a detailed microstructural analysis was performed using FESEM, x-ray diffraction (XRD), and surface roughness studies. Also, the effect of elevated temperatures on the porosity and pore size distribution of natural fiber UHTCC was evaluated using a MATLAB program based on the image greyscale method. Results from the mechanical characterization revealed a negligible strength loss of just 14.3% and 17.1% was observed with flax and hemp fiber composites, even when exposed to a high thermal gradient of 900 degrees C, attributable to the excellent fiber properties and particle packing of the UHTCC mix. Micro-structural and pore-size distribution analysis revealed that marginal changes occur in the composites if the temperature exceeds 600 degrees C, indicating that UHTCC are both strong and environmentally-friendly for practical applications.