The stability of upstream tailings remains a critical geotechnical challenge due to the inherently weak mechanical properties of fine-grained mine tailings. This study investigated a tailing improvement method using (i) emulsified polymer and (ii) combinations of recycled gypsum and cement kiln dust (CKD). A comprehensive experimental program—including unconfined compressive strength (UCS) analysis, direct shear tests (DSTs), and oedometer consolidation tests—was conducted to assess the performance of various treatment mixtures. The results showed that blends of CKD and gypsum, particularly at a 1:2 ratio and a 10% dosage, significantly improved shear strength, reduced compressibility, and lowered hydraulic conductivity by over an order of magnitude. The inclusion of plaster (commercial gypsum) further enhanced the UCS by more than 100% compared to recycled gypsum and increased the cohesion (c’) values from 0 to 32.8–47.2 kPa. The compression index (cc) decreased from 0.15 to 0.05, and the maximum volumetric strain (εv) at an applied effective stress of 800 kPa decreased from 17% to 5%. Emulsified polymer treatments also enhanced the mechanical and hydraulic properties of the clayey tailings; however, the overall improvements were lower than those achieved with CKD–gypsum blends, suggesting that further optimization of the polymer concentration or its combination with mineral additives may yield better results. These findings offer a foundation for further research into the use of polymers in geoenvironmental applications, particularly for erosion control, contaminant encapsulation, and hydraulic barrier development. Overall, this study highlights the potential of using industrial by-products, such as CKD and gypsum, as sustainable, cost-effective materials to improve tailing performance, while identifying promising directions for polymer-based solutions in geotechnical engineering.
Alsharedah et al. (Wed,) studied this question.