Microanalytical characterizations, mechanical strength and water resistance performance of solidified dredged sludge with industrial solid waste and architecture residue soil

Industrial solid waste (slag, desulphurization gypsum, fly ash) and construction soil architecture residue soil are used to solidify dredged silt to develop a novel cover material. Through the application of shear, compressive, and permeability tests, shear strength parameters, unconfined compressive strength, volume shrinkage and hydraulic conductivity of the cured silt were assessed under the different curing times and wet-dry cycles conditions. The result shown slag played the most significant role in the silt consolidation process, followed by FGD gypsum and fly ash. X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) and nuclear magnetic resonance (NMR) detection methods were employed to determine the hydration products, chemical characteristics, microscopic morphology and pore structure of the solidified sludge, and identify the solidification mechanisms of the industrial waste and slag. After the wet and dry cycles, micropores and foramen (0.1–0.5 µm) continued to dominate pores, accounting for 64–76 % of pore space. Hydration products in the solidified sludge primarily consisted of C-S-H, C-A-S-H, and N-A-S-H gelled products, along with ettringite and zeolite.