The curing mechanism and empirical model for the marine organic soft clay stabilized with calcium carbide residue and silica fume under the optimal ratio

The study aimed to elucidate the curing mechanism and establish an empirical model for the stabilization of marine organic soft clay (MOSC) using a combination of calcium carbide residue (CCR) and silica fume (SF) at the optimal proportion, employing response surface methodology (RSM) in conjunction with multi-scale characterization techniques. Initial investigations involved a series of unconfined compression strength (UCS) tests conducted on CCR and SF to ascertain the most effective dosage of each material for the stabilization of MOSC. Notably, it was observed that CCR exerted a more pronounced influence on enhancing MOSC properties when compared to SF. Further refinement of the optimal CCR-SF ratio was undertaken utilizing RSM, culminating in the establishment of a novel binder, denominated as PZ-2, with a composition ratio of 56% CCR and 44% SF. Characterization through X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), Energy-Dispersive X-ray Spectrometry (EDS) identified the primary products formed within the stabilized MOSC matrix with PZ-2 as comprising C–S–H, calcite, and dolomite. SEM analyses unveiled a substantially improved microstructure characterized by the presence of flocculent and agglomerate products in MOSC stabilized with PZ-2. Moreover, Mercury Intrusion Porosimetry (MIP) results indicated reduced pore volume in cured MOSC as opposed to its raw counterpart, indicative of a stronger microstructural configuration post-stabilization. The salutary effects of PZ-2 on MOSC stabilization were attributed to mechanisms encompassing pozzolanic reactions, neutralization, carbonation, and ion exchange. Additionally, it was noted that PZ-2 offered cost and environmental advantages over conventional Portland cement (PO 32.5). To facilitate practical applications, empirical models predicting the UCS strength of cured MOSC were developed incorporating key parameters such as initial water content (w_i), organic matter content (w_o), and binder content (w_b,) with the optimal mixing ratio. These models demonstrated reliability and utility in guiding effective strategies for strengthening MOSC.