بررسي آزمايشگاهي تأثير نانورس مونت موريلونيت بر خواص خميري و مقاومتي ماسه ي رس‌دار

Laboratory investigation of the NanoMontmorillonite clay effect on Strength and Plasticity properties of the clayey sand

در مطالعه‌ي حاضر، به منظور بررسي تغييرات به وجود آمده در حدود اتربرگ و تنش برشي خاك‌هاي ماسه‌يي رس‌دار از آزمايش‌هاي حدود اتربرگ و برش مستقيم در درصدهاي مختلف نانورس بر روي ماسه‌هاي رس‌دار با تركيب گوناگون درصدهاي ماسه و رس انجام شده است. همچنين، جهت بررسي ميكروسكوپي بافت نمونه‌ها از ميكروسكوپ الكتروني روبشي براي پيمايش سطح نمونه‌ها استفاده شده است. بررسي تصاوير نشان مي‌دهد ذرات نانورس در صورت نبود رس در نمونه‌ي خاك (يعني خاك ماسه‌يي خالص) يا عدم پراكندگي يكنواخت، اثر معكوس در رفتار خاك خواهند داشت. در صورت وجود رس در خاك ماسه‌يي و همچنين پراكنده شدن يكنواخت نانورس در خاك، پارامترهاي ژئوتكنيكي خاك بهبود مي‌يابند. براي خاك مورد مطالعه در پژوهش حاضر، بهترين تركيب از نظر مقاومت برشي، مربوط به خاكي است كه از تركيب 80٪ ماسه و 20٪ تشكيل شده و با افزودن 4٪ نانورس به آن، بهترين نتيجه از نظر مقاومت برشي به دست آمده است.

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.