Effect of Fe<sub>2</sub>O<sub>3</sub> additives on the sintering mechanism of a high strength ceramsite from a CFB fly ash

Ikechukwu Okeke; Peng Liyang; Yuhong Qin; Chukwubuike Chiemerie Onwuagbu; Afreh Paul; Maywish Islam

Effect of Fe₂O₃ additives on the sintering mechanism of a high strength ceramsite from a CFB fly ash

( Vol-12,Issue-7,July 2025 ) OPEN ACCESS

Author(s):

Ikechukwu Okeke, Peng Liyang, Yuhong Qin, Chukwubuike Chiemerie Onwuagbu, Afreh Paul, Maywish Islam

Keywords:

CFB fly ash, Fe2O3, ceramsite, sintering mechanism, liquid-phase sintering, compressive strength

Abstract:

The sustainable reutilization of industrial solid waste offers a viable strategy to address environmental concerns associated with coal-fired power generation. This study investigates the role of Fe₂O₃ additives in enhancing the sintering behavior, microstructural evolution, and structural properties of high-strength ceramsite synthesized from circulating fluidized bed (CFB) fly ash. A series of ceramsite samples with varying Fe₂O₃ contents (0–15 wt%) were sintered at temperatures ranging from 1150°C to 1300°C to evaluate the influence of Fe₂O₃ on material performance. The results revealed that the addition of 5–10 wt% Fe₂O₃ at 1300°C produced optimal results. Microstructural analyses using X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric–differential scanning calorimetry coupled with Fourier-transform infrared spectroscopy (TG-DSC-FTIR) demonstrated that Fe₂O₃ effectively promotes liquid-phase sintering, facilitates mullite crystallization, and improves particle bonding and densification, while simultaneously moderating gas evolution. However, excessive Fe₂O₃ content (>10 wt%) led to reduced strength and densification due to increased porosity and decreased liquid-phase viscosity. This research not only highlights the dual function of Fe₂O₃ as both a fluxing and structural stabilizing agent but also provides a practical route for converting coal-based solid waste into high-performance construction materials. The findings contribute to the advancement of sustainable building technologies and support circular economy goals through efficient resource recovery and waste minimization.