The irreversible agglomeration of wet cellulose nanofibers (CNF) during dehydration, storage, and transportation is a well-recognized challenge in practical application. The present work reports a novel method for obtaining water-redispersible dried CNF by performing surface treatment with poly (ethylene oxide) (PEO) during the freeze-drying process. The CNF used in the experiments were prepared in-house by combining radiation degradation, mechanochemical treatment, and high-pressure homogenization. Various techniques including AFM, XPS, Rheometer, XRD, UV–vis spectrophotometer, FT-IR, Congo red adsorption method, Particle size and ζ-potential analysis were systematically employed to elucidate the structural and interfacial modifications induced by PEO. The results indicate that PEO introduces steric hindrance and fosters intermolecular interactions, which transiently inhibit hydrogen-bond formation during dehydration while allowing re-dispersion through bond reconfiguration upon rehydration. A critical point of PEO content at about 0.10 wt% was identified. Below this value, incomplete surface coverage resulted in inefficient weakening the interaction between CNF. While when the PEO content was high than the point, bridge flocculation became dominant, causing the CNF dispersion to aggregate. This simple and environmentally friendly strategy demonstrates significant potential for facilitating broader practical use of CNF-based materials across various technological fields.
The mismatch in physical properties between traditional mortar and the porous substrate of foam concrete (FC) leads to poor adhesion and cracking, limiting the wider application of FC. In order to address this issue and alleviate the storage pressure of low silica iron tailings (LSIT), this study developed an advanced plastering mortar system for foam concrete blocks through systematic optimization of LSIT. A comprehensive evaluation was conducted on six critical parameters, including the water-cement ratio, the aggregate ratio of LSIT to sand, the content of cement, hydroxypropyl methyl cellulose (HPMC), re-dispersible latex powder (RDP), and polypropylene fiber (PPF), establishing their quantitative impacts on mortar performance. The optimal performance was achieved with a water-cement ratio of 0.84, aggregate ratio of 11:3, cement content of 30%, HPMC content of 0.4%, RDP content of 1.5%, and PPF content of 0.15%, yielding a mortar density of 1447.9 kg/m 3 , 28 d compressive strength of 8.21 MPa, and 104 mm consistency, parameters fully compliant with the M8 grade specifications in JC/T 890-2017. Advanced microstructural characterization (XRD, SEM, and hydration heat analysis) demonstrated that LSIT particles refined the granulometric distribution through microaggregate effects. In addition, C 3 S dissociation was retarded by HPMC through Ca 2+ chelation, extending the induction period of hydration. Moreover, the RDP facilitated interfacial cross-linking via transesterification, forming the core–shell structures of C–S–H and polymer, compared with the control sample, the portlandite content was slightly reduced. Furthermore, the PPF reinforcement is achieved through crack-deflection and bridging mechanisms. The modification system of multi-component materials therefore exhibits a three-fold synergistic action, including the gradation optimization of particles, the regulation of hydration kinetics, and the toughening of the interfacial. These findings establish a viable pathway for high-value utilization of iron tailings in construction materials and simultaneously elucidate the physicochemical mechanisms underlying the interactions of composite modifiers in cementitious systems. Furthermore, the modified additive system serves as a viable template for valorizing diverse solid wastes. Graphical abstract
危险品化学品经营许可证（带存储）