Influence of polypropylene fiber on the explosion resistance and fracture behavior of alumina-spinel castables

Despite the successful preparation of high-performance calcium aluminate cement-bonded castables, occasional explosions have been reported. The occurrence of castable explosions is commonly attributed to water vapor overflow retarding and vapor pressure generated by rapid temperature rise. To enhance the explosion resistance of castables, methods such as incorporating various fibers (e.g., polypropylene [PP], polyethylene [ED], aramidic [Par], and steel fibers) have been proposed. However, limited studies have investigated the impact of fiber content on pore structure and fracture behavior of castables. This study aims to assess the influence of different PP fiber contents on comprehensive properties of castables. The explosion resistance was evaluated in conjunction with air permeability and pore structures, and fracture behavior was tested through wedge splitting tests at both room temperature and elevated temperatures. Results indicated that the addition of PP fibers significantly improves air permeability thus enhancing anti-explosive capabilities. Simultaneously, the combustion of fibers resulted in the formation of residual pores, which contributed to an enhanced resistance against stress-induced damage.