Performance Analysis of Pipe-Jacking Waste Soils Solidified with Cement under Balanced Earth Pressure Conditions

The utilization of pipe-jacking soil poses challenges due to its complex composition, which comprises polyacrylamide (PAM) and sodium bentonite (Na-Ben) surfactants, hindering drainage and solidification. Improper handling may induce environmental pollution. To address this problem, cement solidification was explored after modification with PAM and Na-Ben. By performing indoor resistance tests, freeze–thaw cycles, wet–dry cycles, SEM, XRD, and IR experiments, it was found that within certain ratios, cement solidification effectively stabilizes pipe-jacking waste soil. Specifically, PAM minimally impacts pipe-jacking waste-soil strength, whereas Na-Ben slightly reduces it. Microscopic analysis revealed that although water absorption hinders hydration reactions, PAM (at lower concentrations) promotes mineral particle cohesion during cement solidification. Na-Ben tends to aggregate, leading to uneven internal structure and inhibiting cementitious product formation