Formulation determination and performance study of high-volume fly ash-based grouting fire extinguishing materials

Abstract

Considering the continued advancement of China's industrial sector, a substantial quantity of circulating fluidized bed fly ash (CFBFA) and calcium carbide slag (CS) is generated throughout the production process. Considering the rich calcium content inherent in CFBFA (circulating fluidized bed fly ash) and the inherently alkaline nature of CS(carbide slag), the amalgamation of these two constituents leads to a multitude of hydration reactions, culminating in the synthesis of polymeric grouting materials. This study undertaked a comprehensive examination and regulation of three factors within the binary system: water-cement ratio, CS content, and CS particle size. Through the utilization of scanning electron microscopy (SEM), X-ray diffraction (XRD), and (TG) thermogravimetric analysis, the investigation aims to elucidate the influence mechanism of the composite gelling system comprising fly ash and calcium carbide slag on the compressive strength, setting time, and other pertinent indicators of grouting materials. The data reveals that when the water-cement ratio is set at 0.85, CS content at 30%, and CS ball milling time at 1 h, the resulting grouting material exhibits a fluidity of 279 mm, a water separation ratio of 3.13%, and achieves a strength of 15.6 MPa at 28 days. It boasts a stable and easily transportable slurry, which possesses a certain degree of cementitious performance, effectively sealing off any air leakage channels. Moreover, by subjecting CS to appropriate pre-treatment measures, a suitable quantity of active silicon and aluminum elements can be thoroughly dissolved within the CFBFA (circulating fluidized bed fly ash) slurry system, giving rise to a staggered distribution and dense hydration product structure. Considering the requirements for gangue mountain fire extinguishing slurry, a CFBFA-CS based grouting material formula has been carefully selected. Additionally, simulation grouting fire extinguishing experiments have demonstrated that the injection of the slurry is highly effective in reducing the temperature of the combustion test block, isolating oxygen, and lowering the temperature within the combustion zone. After 5 h, the temperature drops to below 100 °C, and no re-ignition phenomena are observed. The outcomes of this research can provide valuable scientific guidance for the development of high-performance fire extinguishing grouting materials utilizing fly ash and carbide slag.