Comparison of reconstitution methods for mine tailings materials

The paper studies the effect of sample reconstitution for three commonly employed procedures, namely static compaction and standard and modified moist tamping methods, in the context of laboratory testing of mine tailing materials. The effect of initial water content and compaction energy on the resulting densities and uniformity of the samples are examined. Equivalencies between different reconstitution methods were established to attain a given target density. Then, the effect of the resulting fabric was investigated by means of isotopically consolidated undrained triaxial tests, on samples prepared with similar densities and water contents but with different reconstitution techniques. The results showed that all reconstitution techniques studied produced samples with acceptable uniformity and good repeatability. Although similar results were obtained across the different methods, the modified moist tamping technique yielded slightly higher undrained peak strengths and exhibited a more pronounced hardening behavior upon reaching the critical state line compared to the static compaction method. In contrast, the moist tamping and static compaction methods produced comparable responses in loose specimens. These results suggest that dynamic and static reconstitution methods may create subtle differences in the fabric of the samples, influencing their behavior under shearing.