عنوان مقاله [English]
The improvement of soil treatment by additives is one of the most critical issues in geotechnical engineering. Typical additives such as cement, lime, fly ash, and bitumen have been investigated in the past. Nanomaterials have unique features. The application of this type of material has led to a significant development in other branches of engineering. However, in geotechnical engineering, the investigation of the effects of this type of material is a new subject. Hence, in the present research, the effects of nano clay on geotechnical parameters of clayey sand are investigated. The principal purpose of investigation in this scale is the creation of new compounds with changes in ingredients and the detection of a new class of materials with new functions. These types of researches can make an appropriate base for future researches in this context.
The Atterberg limits test and direct shear tests were carried out on different types of clayey sand. Various percentages of nano clay were used in the study. Ball mill was applied for uniform dispersion of nanoparticles. Also, in order to obtain optimum water content and maximum specific weight for prototyping, a standard compaction test was carried out on samples without nano clay particles.
Based on the results, in general trends of tests, liquid limit and plastic limit are increased by increasing nano clay. The plasticity index has decreased when the percentage of the nano clay is increased by up to 1%. The plasticity index has increased again in a higher percentage of nano clays (more than 1%). Also, the shear strength of clayey sand in direct shear tests is improved in a specific percentage of nano clay. The optimum percentage of the nano clay for the friction angle φ is 1% in the direct shear test, and its best percentage for the cohesion C is 4%. Also, nano clay has a negative effect on the shear strength of pure sand. Therefore, according to the results of experiments, nanoparticles can be an acceptable choice for improving the geotechnical properties of clayey sand soils.