Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Strength improvement and micromechanism of inorganic/organic additive-modified magnesium oxychloride cement solidified sludge
Graphical abstract Display Omitted
Highlights Phosphoric acid, urea–formaldehyde resin and citric acid are confirmed most efficient. Chemical additives improve shear and compressive strength of MOC solidified sludge. Cohesion and internal friction angle show first an upward and later a downward trend. Yielding stress shows a trend of rise with curing age and fall with immersion period. Phase 5, phase 3 and brucite are identified as major phases for strength improvement.
Abstract The beneficial reuse of cement-treated waste sludge in construction sector is an intractable challenge in the context of sustainable development. To exploit the potential of magnesium oxychloride cement (MOC) as cementing binder in substitution for Portland cement, various inorganic/organic additives are imported to overcome the key defect of MOC – instability in water and improve the water resistance of MOC solidified sludge. To achieve this goal, the mechanical and microstructural studies by compressive strength, water immersion, shear strength, compressibility, X-ray diffraction and scanning electron microscopy tests are comprehensively examined. Key outcomes reveal that: (i) Compressive strength, shear strength and water resistance of MOC solidified sludge can be significantly improved by a reasonable dosage of chemical additives, especially for phosphoric acid (3%), citric acid (4%) and urea–formaldehyde resin (12%), (ii) Shear strength versus normal stress relationship can be well represented by the approximately linear function, while cohesion and internal friction angle show an upward tendency with standard curing age and later a downward trend with water immersion period, (iii) Yielding stress exhibits a tendency of first rise and then fall with curing age, but compression index has a trend of first decline and then increase, and (iv) Lamellar Mg(OH)2, rod-like/plate-like phase 5 and phase 3 are identified as the major hydrated products conducive to the excellent performance of additive-modified MOC solidified sludge. A better understanding of the improvement of chemical additives on MOC solidified sludge is helpful to synthesize MOC that exhibits properties suitable for application as a cementing binder.
Strength improvement and micromechanism of inorganic/organic additive-modified magnesium oxychloride cement solidified sludge
Graphical abstract Display Omitted
Highlights Phosphoric acid, urea–formaldehyde resin and citric acid are confirmed most efficient. Chemical additives improve shear and compressive strength of MOC solidified sludge. Cohesion and internal friction angle show first an upward and later a downward trend. Yielding stress shows a trend of rise with curing age and fall with immersion period. Phase 5, phase 3 and brucite are identified as major phases for strength improvement.
Abstract The beneficial reuse of cement-treated waste sludge in construction sector is an intractable challenge in the context of sustainable development. To exploit the potential of magnesium oxychloride cement (MOC) as cementing binder in substitution for Portland cement, various inorganic/organic additives are imported to overcome the key defect of MOC – instability in water and improve the water resistance of MOC solidified sludge. To achieve this goal, the mechanical and microstructural studies by compressive strength, water immersion, shear strength, compressibility, X-ray diffraction and scanning electron microscopy tests are comprehensively examined. Key outcomes reveal that: (i) Compressive strength, shear strength and water resistance of MOC solidified sludge can be significantly improved by a reasonable dosage of chemical additives, especially for phosphoric acid (3%), citric acid (4%) and urea–formaldehyde resin (12%), (ii) Shear strength versus normal stress relationship can be well represented by the approximately linear function, while cohesion and internal friction angle show an upward tendency with standard curing age and later a downward trend with water immersion period, (iii) Yielding stress exhibits a tendency of first rise and then fall with curing age, but compression index has a trend of first decline and then increase, and (iv) Lamellar Mg(OH)2, rod-like/plate-like phase 5 and phase 3 are identified as the major hydrated products conducive to the excellent performance of additive-modified MOC solidified sludge. A better understanding of the improvement of chemical additives on MOC solidified sludge is helpful to synthesize MOC that exhibits properties suitable for application as a cementing binder.
Strength improvement and micromechanism of inorganic/organic additive-modified magnesium oxychloride cement solidified sludge
Wang, Dongxing (Autor:in) / Yang, Duo (Autor:in) / Yuan, Yong (Autor:in)
19.12.2022
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch