Amorphous self‐glazed, chopped basalt fiber reinforced, geopolymer‐based composites

Abstract Geopolymer composites reinforced with refractory, chopped basalt fibers, and low melting glass were fabricated and heat treated at higher temperatures. K ₂ O·Al ₂ O ₃ ·4SiO ₂ ·11H ₂ O was the stoichiometric composition of the potassium‐based geopolymer which was produced from water glass (fumed silica, deionized water, potassium hydroxide), and metakaolin. Addition of low melting glass (T _m ~815°C) increased the flexure strength of the composites to ~5 MPa after heat treatment above 1000°C to 1200°C. A Weibull statistical analysis was performed exhibiting how the amorphous self‐healing and self‐glazing effect of the glass frit significantly improved the flexure strength of the geopolymer and ceramic composites after exposure for 1 hour to high temperatures. At 950‐1000°C, the K‐based geopolymer converted to primarily a crystalline leucite ceramic, but the basalt fiber remained intact, and the melted glass frit flowed out of the surface cracks and sealed them. 1150℃ was determined to be the optimum heat treatment temperature, as at ≤1200°C, the basalt fibers melt and the strength of the reinforcement in the composites is significantly reduced. The amorphous self‐healing and amorphous self‐glazing effects of the glass frit significantly improved the room temperature flexure strength of the heat‐treated geopolymer and ceramic composites.