Green shotcrete preparation based on coal gasification furnace slag and application of solid waste resources in roadway support

Abstract This study utilized coal-to-oil furnace slag as a substitute for natural sand and gravel to develop slag-based shotcrete. The feasibility of this approach was validated through the analysis of the fundamental physical properties of the coal-to-oil furnace slag. The mix design of the slag concrete was optimized by incorporating fly ash and adjusting the dosage of re-dispersible latex powder, resulting in the preparation of the corresponding slag-based shotcrete. The experiments showed that the particle size distribution of the coal-to-oil furnace slag was similar to that of conventional sand and gravel. Coal-to-oil furnace slag exhibits particle size and physical properties comparable to those of construction sand. When the water-cement ratio is set at 0.25 and the fly ash substitution rate is 10%, the resulting concrete demonstrates excellent strength performance. The addition of re-dispersible latex powder enhances the flexural-to-compressive strength ratio, significantly improving the toughness and bond strength of the slag concrete. Fly ash contributes positively to the development of later-age strength. Ultimately, an optimized mix design and appropriate admixture dosages yielded a C25 coal-to-oil slag shotcrete with reduced rebound rates and dust concentrations.