The preparation of sintered ceramsite is one of the effective methods for the high-value recycling of engineering spoil. However, the conventional sintering process suffers from drawbacks such as high energy consumption, uneven heating, and low efficiency, which restrict the further development of spoil resource recovery. Microwave sintering possesses the advantages of rapid heating and volumetric heating. In this study, engineering spoil was used as the raw material to prepare ceramsite via microwave sintering, and the physical and mechanical properties of the ceramsite were systematically investigated. The effects of microwave sintering and conventional muffle furnace sintering on the surface morphology, microstructure, phase composition, and physicomechanical properties of ceramsite were comprehensively compared. Additionally, the regulatory mechanisms of process parameters (heating rate, sintering temperature, and holding time) on the microwave sintering effect of engineering spoil-based ceramsite were explored. Comparative analysis of apparent morphology and microstructure indicates that microwave sintering can effectively reduce the sintering temperature of ceramsite by 40-60°C and complete sintering at a heating rate far exceeding that of conventional heating (up to 50°C/min in this study). Benefiting from the rapid heating rate characteristic of microwave heating, the as-prepared ceramsite has finer grains and exhibits superior mechanical properties at the same density. Analysis of process parameters reveals that sintering temperature is the core factor determining the properties of microwave-sintered ceramsite, while holding time can regulate the pore structure, enabling the ceramsite to maintain sufficient compressive strength while achieving lighter weight. • Microwave sintering reduces the ceramsite sintering temperature by 40–60 °C • Microwave-sintered ceramsite exhibits superior physicomechanical properties • Microwave sintering for ceramsite features high efficiency and controllable performance
Geng et al. (Sun,) studied this question.