Obsidian: A Pioneering Natural Resource for Green, Fire-Resistant Composite Material Industries

A cleaner production approach was employed to develop an innovative and eco-friendly, fire-resistant composite material that boasts exceptional mechanical performance and is capable of withstanding harsh conditions. Novel obsidian (OB) and metakaolin (MK) were individually mixed with NaOH at different ratios ranging from 8 to 12 wt %. Each material was subjected to only 80 °C, forming alkali-activated obsidian (AAOB) and metakaolin-based geopolymer (MKBG). Extensive analyses, including compressive strength, thermal conductivity, X-ray diffraction (XRD), X-ray fluorescence (XRF), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) analysis, confirmed the performance of both AAOB and MKBG. The AAOB outshined MKBG in fire resistance and mechanical strength, boasting impressive compressive strengths of 36.5, 69, and 101 MPa, respectively at day one. In contrast, MKBG lagged behind, with compressive strengths of 9.1, 23.24, and 25.66 MPa under the same conditions. Furthermore, AAOB exhibited a significantly higher porosity (80%) at 1000 °C and a lower thermal conductivity of 0.193 W/mK, compared to MKBG, which possessed a lower porosity (33%) and higher thermal conductivity of 0.901 W/mK. The AAOB represents a significant leap in the green revolution for sustainable fire-resistant composite materials. Its versatility extends across various sectors, notably in ultrahigh-temperature industrial and construction applications.