Evaluating the GO-CNTs-MC Composite for Grouting in High-Water-Content Sandy Sediments

Grouting is essential for preventing water and sand inrush in deep-sea mining, yet conventional cement-based materials often exhibit inadequate early strength, poor fluidity, and low injectability under high-pressure and low-temperature conditions. To address these limitations, a modified cement composite was developed by incorporating graphene oxide (GO), multi-walled carbon nanotubes (MWCNTs), and methyl cellulose (MC) into a high water-cement ratio system. This material demonstrates enhanced mechanical strength and permeability, making it suitable for reinforcing weak seabed sediments. Experimental results using a custom grouted sample system identified an optimal MC content of 0.18 wt%. Orthogonal range analysis revealed that the water-cement ratio is the most critical factor governing the uniaxial compressive strength (UCS) of grouted sediment, followed by sand size and nanomaterial content. The optimal grouting combination was determined to be a water-cement ratio of 0.8, a sand size of 1~2 mm, and a total nanomaterial content of 0.03 wt% (CNTs: 0.02 wt%, GO: 0.01 wt%). The study establishes a quantitative link between material properties and mechanical behaviour, providing a theoretical basis for grouting parameter design and practical support for deep-sea mining challenges such as foundation reinforcement and liquefaction prevention.