| dc.description.abstract | This study investigates the characteristics and reuse feasibility of fly ash produced from co-combustion of coal and three different compositions of Solid Recovered Fuel (SRF). It pri-marily focuses on the impact of reactive aluminum and free calcium oxide (CaO) on the volu-metric stability and workability of cement-based materials.
The results indicate that reactive aluminum in the fly ash generates hydrogen gas when used in cement-based materials, leading to volumetric instability. Meanwhile, free CaO in the fly ash reacts exothermically with water to form calcium hydroxide (Ca(OH)₂), causing volumetric expansion and poor workability. The study examines the effectiveness of cement solidification in treating fly ash to improve its stability and workability. It also proposes appropriate reuse strategies based on fly ash characteristics, such as reactive aluminum content, free CaO content, and strength activity index.
In the cement paste formulation, different types of co-combusted fly ash exhibit distinct properties. CCFA(A) fly ash, with high reactive aluminum and free CaO content, shows signif-icant volumetric expansion and strength development issues. CCFA(B) fly ash produces less hydrogen gas but is still affected by the exothermic reaction of free CaO, impacting strength. CCFA(C) fly ash, containing low reactive aluminum but high free CaO, causes specimen rup-ture at high temperatures. For plastic materials, CCFA(A) and CCFA(C) fly ashes exhibit good compressive strength and volumetric stability after vibratory compaction. The crushed material formulation demonstrates that breaking down the solidified material into granules allows for size control and good physical properties, making it suitable for engineering fill.
The study further proposes reuse guidelines for co-combusted fly ash based on reactive aluminum content, free CaO content, and strength activity index. It includes recommendations for plastic material formulation, paste formulation, and crushed material formulation, emphasiz-ing the importance of testing to ensure safe and effective reuse. This research offers novel tech-nical pathways for the treatment and reuse of co-combusted fly ash, contributing to environ-mental pollution reduction and promoting sustainable resource utilization. | en_US |