The effect of basalt stone cutting waste on the high-temperature performance of fly ash-based geopolymers

Abstract

In this study, fly ash-based geopolymer mortars were produced with 0, 20, 40, and 60 wt% basalt stone cutting waste (BSCW) and thermally cured at 80 degrees C or 100 degrees C for 8 h and 24 h. Prismatic specimens were tested for flexural and compressive strength at 7 and 28 days. The 20 % BSCW mix cured at 100 degrees C for 24 h achieved the highest 28-day compressive strength (32.76 MPa), while the 60 % BSCW mix under the same regime reached the maximum flexural strength (12.76 MPa). Notably, the energy-efficient 100 degrees C-8 h cure yielded 31.67 MPa compressive and 11.55 MPa flexural strengths, within 3 % of the 24 h values. After exposure to 400, 600, and 800 degrees C, mortars with 60 % BSCW exhibited the least strength loss (<= 15 % at 800 degrees C), compared to up to 25 % loss in pure fly ash mortars. These findings underscore the potential of BSCW not merely as an inert filler but as a reactive precursor in geopolymer synthesis. Its combination with fly ash enhances high-temperature performance and supports the valorization of industrial waste in the development of sustainable binder systems.