Experimental Study on the Effect of Hydroxyethyl Cellulose on the Friction-Reducing Performance of Thixotropic Slurries in Pipe Jacking Construction

In pipe jacking construction, thixotropic slurry critically governs lubrication, friction reduction, and ground support. This study evaluated slurry performance through six parameters: specific gravity (SG), pH, fluid loss (FL), water separation rate (WSR), filter cake thickness (FCT), and funnel viscosity (FV). Orthogonal experiments optimizing bentonite, carboxymethyl cellulose (CMC), and sodium carbonate (Na₂CO₃) ratios established 10 wt.% bentonite, 0.4 wt.% CMC, and 0.3 wt.% Na₂CO₃ as the optimal formulation. Subsequently, to address performance limitations in challenging conditions, this study introduces hydroxyethyl cellulose (HEC) as a novel additive, with potential advantages under high-salinity and variable pH conditions. Comparative experiments demonstrated that HEC, as a non-ionic water-soluble cellulose, not only significantly increases FV and reduces FL while maintaining SG, FCT, and WSR within acceptable thresholds, but also exhibits superior pH stability compared to CMC. The microstructures of the three thixotropic slurries with distinct compositions were examined using scanning electron microscopy (SEM) based on the aforementioned results, leading to systematic analysis of their structural characteristics and friction-reduction mechanisms that microscopically demonstrated the good compatibility between HEC and bentonite.These findings highlight HEC’s potential as an effective alternative in pipe jacking, particularly in demanding geological environments.