Abstract:

To realize the high-value and large-scale utilization of industrial solid wastes and address the high energy consumption and high carbon emission problems of traditional sintered ceramsite， this study integrates core-shell structure design with interface modification strategy. Using stone tailing powder （STP） and flue gas desulfurization gypsum （FGDG） as the main raw materials， this work prepares high-volume solid waste-based non-sintered ceramsite. The dual bonding interface strengthening mechanism anchored by Si—O—Si covalent bonds and bridged by carboxyl—Ca^2＋ coordination bonds of the modifier was revealed. The shell proportioning and modifier synthesis process were optimized via orthogonal tests. The effects of modifier dosage， water-to-material ratio and curing age on the properties of ceramsite were systematically investigated， and XRD， SEM， and FT-IR were adopted for microscopic characterization. The results show that under the optimal formulation， the mass ratio of flue gas desulfurization gypsum to mineral powder is 1∶2， the mass fraction of stone tailing powder is 60%， the cement content is 8%， the modifier dosage is 2.0%， the water-to-material ratio is 0.24， and the curing age is 28 d. The prepared ceramsite achieves a cylinder compressive strength of 4.8 MPa， a bulk density of 751.2 kg/m³， and the 1 h water absorption is reduced to 7.1%， which complies with “Lightweight aggregates and their test methods—part 1： Lightweight aggregates” （GB/T 17431.1—2010）. The ceramsite exhibits excellent application performance in thermal insulation partition boards and lightweight concrete， providing theoretical support and a feasible technical route for the preparation of high-performance lightweight aggregates from industrial solid wastes.

Key words: flue gas desulfurization gypsum, stone tailings powder, non-sintered ceramsite, core-shell structure, interfacial modification, lightweight concrete