Development of eco-friendly alkali-activated nanocomposites comprising micro-fibers at ambient curing conditions

Abstract

Geopolymers (GOPL) can play a vital role in the sustainability of concrete construction. The addition of nanoparticles and micro-fibers to GOPL can improve the mechanical and microstructural performance by densifying the matrix and providing the bridging effect against the internal cracking mechanism. Therefore, an extensive investigation on the improvement of the various characteristics of the GOPL is required to make it feasible for practical applications. Moreover, the combined effect of nanoparticles and micro-fibers on various features of GOPL needs further insights. This study investigates the microstructural, mechanical, fracture, and toughness performance of micro-basalt fiber (MBF)-reinforced coal ash-made GOPL using different proportions of nano-sodium oxide at ambient curing conditions. The percentage of nano-sodium oxide examined in the present study varied from 0% to 4% by weight. The MBF amount is kept the same for all fabricated samples at 0.5% by weight. Scanning electron microscopy is used for assessing the microstructural cracking and failure behavior of GOPL pastes. The findings of the present study divulged that the usage of 3% nano-sodium oxide in MBF-reinforced GOPL mix presented the highest increase of 29%, 55%, 24%, and 60% for the compression strength, flexure strength, fracture toughness, and impact strength, respectively. Further increase in the content of nano-sodium oxide prompted the agglomeration of nanoparticles leading to a reduction in the performance of the GOPL. The outcomes of scanned electron microscopy delineated that the addition of nano-sodium oxide refined the interfacial regions and promoted the polymerization process of the GOPL which enriched the microstructure and fabricated a highly densified GOPL paste.

Keywords

• Basalt fiber
• Coal ash
• Geopolymer
• Hardness
• Nano-sodium oxide
• Scanning electron microscope