Study on corrosion resistance and microstructure of modified sediment geopolymer materials

Utilizing sediment to manufacture geopolymer materials by alkali-activated modification is an eco-friendly and economical strategy. Investigating its corrosion resistance properties is crucial for enhancing the durability and structural stability of the materials and is the key to promoting their widespread application. In this paper, the combined effects of modifiers, mineral admixtures, and corrosion conditions on the corrosion resistance, mechanical strength, and microstructure of modified sediment geopolymer materials were thoroughly investigated. The mechanical properties of materials were evaluated by universal press, and the mineral composition and microstructure of the materials were analyzed by XRD, SEM and TG. The results reveal that the strength of the modified sediment material are significantly improved. The highest compressive strength of the modified sediment samples reached 15.84 MPa, which was much higher than that of the modified sediment samples without additives. The optimum softening coefficient of the sample is 0.79, and its water resistance is exceptional. The highest compressive strength reaches 15.04 MPa and 14.43 MPa respectively in acid and alkali environment, and its corrosion resistance is better than that of sediment materials without additives. The microstructure analyzed clearly indicated that the C–S–H gels, as the main hydration products, effectively promoted the close bonding of the sediment particles and filled the pores and microcracks inside the specimens, which significantly enhanced the strength and corrosion resistance of the material.