Strength and durability characteristics of basalt fiber-based engineered geopolymer composites under elevated temperature

ABSTRACT This study explores the mechanical properties and environmental sustainability of basalt fiber-based Engineered Geopolymer Composites (BFEGC). Trial mixes, were developed and analyzed to determine their flowability and compressive strength, leading to the identification of an optimal formulation with a compressive strength of 55.34 MPa. The optimal mix was also found to exhibit split tensile and flexural strengths of 15.5 MPa and 5.13 MPa, respectively. Durability assessments of this mix were conducted through water absorption, sorptivity, and chloride penetration tests, confirming compliance with codal requirements. Thermal resistance evaluations were performed under varying conditions: low (300°C for 30 minutes), moderate (600°C for 20 minutes), and high (900°C for 15 minutes), followed by both rapid and gradual cooling. The minimal compressive strength degradation was observed for the optimal mix (Mix 4) at 300°C, with a decrease of only 19.40%. Additionally, the strain hardening behavior of BFEGC samples at elevated temperatures was studied, revealing microstructural stability up to 300°C during gradual cooling. TGA results indicated that the geopolymer matrix and basalt fibers work synergistically, resulting in a minor weight loss of only 2–5% at 300°C. The environmental impact of BFEGC was also assessed, demonstrating its potential to significantly reduce carbon emissions and embodied energy. BFEGC finds application in strengthening structural elements in fire-prone environments due to its thermal stability, low shrinkage, and strength retention at high temperatures.