Investigation of the Impacts of Nanomaterials on the Micromechanical Properties of Gypseous Soils

Soil stabilization is essential to improve the undesirable geotechnical properties of soil. This study presents using nanoclay and nanosilica to improve the geotechnical properties of gypseous soils. Two types of gypseous soils were collected from two different Iraq sites. The first sample was obtained from Al-Najaf city (42% gypsum content), and the second sample was obtained from Al-Samawa city (54% gypsum content). To improve the geotechnical properties of gypseous soils, three percentages by mass (1, 2, and 4%) of nanoclay and nanosilica were mixed with each soil. The traditional geotechnical tests were performed on the soil samples treated with nanomaterials. Also, the collapsibility, compressibility, and shear strength in dry and soaked conditions were measured. These tests were compared with reference soil samples to measure the efficiency of using nanomaterials in improving the geotechnical properties of gypseous soils. To understand the interaction mechanism between the particles of gypseous soils and nanomaterials, Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy were carried out on selected soil samples. Based on FT-IR, XRD, and SEM results, the nanomaterials construct bridges between particles of soil. Also, the results of collapse tests marked that using 4% of nanomaterials decrease the collapse potential of gypseous soils by more than 50%.