پديد آورندگان :
رزاقيان قاديكلايي مهرداد دانشگاه علم و صنعت ايران - دانشكده مهندسي عمران , حبيب نژاد كورايم اصغر دانشگاه علم و صنعت ايران - دانشكده مهندسي عمران , غرقي مهيار دانشگاه علم و صنعت ايران - دانشكده مهندسي عمران , شريف عليرضا دانشگاه تربيت مدرس - دانشكده مهندسي شيمي
چكيده فارسي :
در دهه هاي اخير مطالعات زيادي در زمينه تاثير نانو ذرات رس بر خصوصيات كامپوزيت هاي سيماني انجام شده است. بااين وجود، برخلاف خواص مطلوب نانوذرات هالوسيت از جمله سطح ويژه بالا، خاصيت پوزولاني، نسبت طول به قطر قابل ملاحظه كه مي تواند تاثير قابل ملاحظه اي بر دوام بتن داشته باشد تحقيقات اندكي در رابطه با تاثير اين نانوذرات به عنوان زير شاخه اي از نانو ذرات رس بر خصوصيات كامپوزيت هاي سيماني انجام شده است. لذا در اين تحقيق تاثير نانو ذرات هالوسيت بر عملكرد ملات سيماني ارزيابي شده و كارايي و نفوذپذيري نمونه هاي ملات حاوي 3 درصد نانولوله هالوسيت مورد بررسي قرارگرفته است. نتايج اين پژوهش حاكي از افزايش 28 درصدي مقاومت الكتريكي، كاهش تقريبي 26 درصد نرخ جذب آب، كاهش حدودي 23 درصد در نرخ دفع آب و همچنين كاهش كارايي و افزايش سرعت هيدراتاسيون ملات حاوي 3 درصد نانولوله هالوسيت در مقايسه با نمونه ملات شاهد بوده است. اين نتايج بيانگر آن است كه نانو لوله هالوسيت مي تواند به عنوان يك نانو ذره مناسب براي بهبود خواص بتن مورداستفاده قرار گيرد. نتايج اين تحقيق مي تواند به كاربرد نانوذرات در ماتريس هاي سيماني كمك نموده و زمينه استفاده از سيمان هاي كاراتر را فراهم نمايد.
چكيده لاتين :
In the last decades, the development of nanotechnology has been rising and nanomaterials have been widely used in combination with many traditional materials. The prominent chemical and physical properties of nanomaterials enable them to play an important role in various applications such as modifying the structure of materials, improving the properties of composites, and manufacturing new multifunctional products. The building industry has not been exempted from this rule. Many studies have been carried out on the effect of nanoparticles on concrete performance and most of them demonstrated the improvement of concrete properties. There are a lot of studies on the effect of nanoclay on cement composites. However, there are little researches on the halloysite nanotube (HNT) effect, as subcategories of nanoclay, on the properties of cement composites. Halloysites are a kind of mineral clay which are often produced by air-induced erosion or by thermal transformation of ultramafic rocks, volcanic glasses, and pumice. They are chemically similar to kaolinite but, unit layers in halloysites are separated by a monolayer of water molecules. In general, halloysites have different shapes and exist in the plate, spherical, and tubular forms. The tubular structure is the dominant form of halloysite in nature. Chemically, the outer surface of the HNTs has properties similar to SiO2 while the inner cylinder core is related to Al2O3. Due to the tubular geometry, HNTs like carbon nanotubes could be classified as one-dimensional nanoparticles. Halloysite can grow into long multi-walled tubules, which morphologically resemble to multi-walled carbon nanotubes. In terms of dimensional characteristics, HNTs have an external diameter of about 30 to 190 nm, an inner diameter of about 10 to 100 nm and a length between 3 to 30 µm. Halloysite characteristics could be sum up as high length to diameter (L/D) ratio, high specific surface, large pore volume, low density in surface, and pozzolanic properties. Mechanical properties of HNTs could make them an ideal reinforcing additive to improve the mechanical properties of cement composites. In addition, due to the nano scale size of HNTs, they can play the role of filler and make a denser and stronger microstructure. Therefore, in this research, the effect of HNTs on the performance of cement mortar was evaluated and the workability and permeability of mortar samples containing 3% halloysite nanotubes were presented. The results indicated an increase of more than 28% of electrical resistance, a decrease of approximately 26% of water absorption rate, 23% reduction in water repellent, a decrease in the workability, and an increment in the rate of hydration of cement mortar due to the incorporation of 3% halloysite nanotube. These results indicate that halloysite nanotubes can be used as an appropriate nanoparticle to improve the properties of cementitious composites. The pozzolanic properties of HNTs enable them to decrease the permeability of cementitious matrices. Silicate of HNTs react with calcium ions of hydrated cement and increase the calcium silicate hydrate gel. This could lead to an enhancement in the durability of cementitious matrices. This paper can provide more insights on the application of nanoparticles with cementitious composites.
