Research paperStrength enhancement of clean and kerosene-contaminated sandy lean clay using nanoclay and nanosilica as additives

- 0.5-2.5 wt% nanoparticles produce significant gains in soil strength and stiffness.
- For CL soil, 1% nanoclay or 1.5% nanosilica produce greatest strength.
- For 12% kerosene-contaminated soil, 2.5% nanosilica produces greatest strength.
- Significant strength gain with curing period, particularly for nanoclay additive
- Nanoclay more efficient than nanosilica in improving soil undrained strength

In oil-rich countries, contamination of soils with oil products can occur during the refining, transportation and operation processes. From a geotechnical viewpoint, oil contamination adversely affects the geomechanical behaviour/properties. Also, depending on the circumstances, some fine soil deposits may have insufficient bearing capacity or undergo excessive settlement under loading. Both scenarios described typically require some form of ground improvement. Given their widespread application in various fields, the selective use of nanoparticles to improve the geotechnical properties can be a new approach. This paper presents an experimental study performed at bench scale on sandy lean clay (CL) soil with two main objectives: (i) to investigate the effect of increasing kerosene content on its constitutive behaviour/strength; (ii) to investigate the strength and stiffness improvements achieved for the clean and kerosene-contaminated soil using nanoclay and nanosilica materials as additives, both independently and together, including the effect of curing period. Significant and progressive reductions in strength and stiffness occurred for ≥ 8 wt% kerosene content. Significant gains in soil strength and stiffness were achieved for 0.5-2.5 wt% nanoparticle addition. For the clean CL soil, 1 wt% nanoclay or 1.5 wt% nanosilica addition produced the greatest improvement in strength. Compared with nanosilica, on the basis of its lower optimum wt% value required for both the clean and contaminated CL soil materials, the nanoclay material investigated was deemed more efficient in improving the uniaxial strength/stiffness.