Polymer-modified bentonite (PMB) has been extensively investigated for industrial waste containment due to its low hydraulic conductivity and salt resistance. Its performance under actual field conditions, however, remains insufficiently documented. Swelling and heavy-metal adsorption behaviors of PMB and sodium bentonite (NaB) were systematically compared under varied contaminant solutions. The hydraulic performance of polymer-modified bentonite-sand (PMB-S) and sodium bentonite-sand (NaB-S) mixtures was evaluated. Furthermore, the feasibility of using in situ phosphate mine waste as a substrate material in PMB-based barriers was discussed. Results show that across the pH range of 2 to 12, PMB always maintains a free swelling index greater than 50 mL/2 g, significantly higher than that of NaB. Additionally, its adsorption performance for Pb2+ and Cu2+ is superior to that of NaB, with the removal rates increasing by 58.42% and 61.31%, respectively, particularly in acidic environments. The hydraulic conductivity of PMB-S is significantly lower than that of NaB-S, and may consistently achieve values below 1×10-8 cm/s in most contaminated environments. The mixtures of PMB with three phosphate mine wastes have comparable hydraulic performance to PMB-S, confirming its feasibility as a barrier material. Furthermore, field demonstrations in alkaline lead-zinc and acidic phosphogypsum tailings validate the robust hydraulic and contaminant barrier properties of PMB-S under actual conditions.

polymer-modified bentonite  /  swelling characteristics  /  adsorption properties  /  hydraulic conductivity  /  in-situ test