Assessing the Swelling and Permeability Behavior of Novel Marble Dust–Bentonite with Sand–Bentonite Mixes for Use as a Landfill Liner Material

Sand–Bentonite (S–B) mix is used frequently as a landfill liner material in several waste containment projects. However, the scarcity of sand and adverse effects (i.e., crack, shrinkage, and swelling) of using bentonite has forced us to find out the suitable, sustainable, and economical material which can fulfill the purpose of landfill liner material. Hence, the present study is aimed to assess the suitability of waste material, i.e., marble dust (MD) with bentonite to be utilized as landfill liner material as an alternative to S–B mix. Detailed experimental studies have been conducted to investigate the compaction characteristics, free swell index (FSI), one-dimensional swelling percentage, and permeability behavior of varying proportions (0–95%) of S–B and MD–B mixes. Results revealed that behaviors of both S–B and MD–B mixes are pronounced to be identical and hence, marble dust can be used as an alternative to sand with bentonite. It has been observed that the substitution of sand and marble dust beyond 40% bentonite satisfies the criteria to be used as a landfill liner material. The relationships of swelling percentage with FSI and the influence of compaction characteristics on the permeability behaviors of both mix combinations are brought out clearly. Further, microstructural examinations along with chemical composition analyses of samples are performed to elucidate the experimental results.