Investigation of the effects of aluminum paste produced using different fatty acids on the autoclaved aerated concrete material

Tez (Yüksek Lisans)-- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2019Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2019Günümüz yapı malzemelerinden dünyanın her yerinde kabul görüp üretilen ve kullanılan gaz beton, yangın güvenliği, ısı yalıtım özellikleri ve en önemlisi deprem bölgesinde bulunan ülkemizdeki yapıların güvenle inşa edilmesi açısından en fazla tercih edilen malzemelerin başında gelmektedir. Gazbeton üretimi için kireç, çimento, kum, alçı gibi birçok hammadde girdi olarak kullanılmaktadır. Gazbetona hacim kazandıran ve boşluklu yapısının oluşmasına sebep olan alüminyum tozu da bu hammaddelerle beraber oldukça fazla öneme sahip bir girdidir. Gazbetona en önemli avantajı sağlayıp hem hafifliğini hem de ısı ve ses yalıtım özelliğini kazandıran boşluklu yapı büyük ölçüde alüminyum toz malzemeler sonucunda oluşmaktadır. Alüminyum toz malzeme bu denli öneme sahipken aynı zamanda kullanımından doğan ciddi tehlikeler de barındırmaktadır. Gazbeton prosesinde reaksiyon sonucu hidrojen gazı oluşturan alüminyum toz malzemeler havaya yayılabilecek oldukça ince tanecik yapısına sahiptir. Bu sayede en küçük bir tetikleyici (asit, alkol, oksitleyici maddelerle, kıvılcım kaynağı) ile temas ettiğinde yanma ve dahası patlama riski taşımaktadır. Havaya yayılan küçük toz taneleri yanarken birbirini tetiklediğinden, oluşabilecek bir yangının kontrol altına alınması da zordur. Ayrıca alüminyum tozu uzun süren maruziyetlerde insan vücudunda ağır metal birikiminden kaynaklanan sağlık sorunlarına da sebebiyet vermektedir. Böylelikle alüminyum tozu ile çalışmak zorunda kalan kişiler için ciddi tehlikeler barındırmaktadır. Tüm bu sebeplerle bu malzemenin yerine geçebilecek tozuma ve havada dağılma riski olmayan solvent ile karışabilen alüminyum bazlı malzemelere ihtiyaç doğmuş, alüminyum pasta adı verilen ürünler kullanılmaya başlanmıştır. Hem prosese besleme kolaylığı açısından hem de güvenilirliği ile alüminyum pasta malzemeler, bir alüminyum kaynağı ve belirli kimyasal malzemeler içeren ve gaz betona boşluklu yapı kazandıran bir kabartıcı malzeme olarak gün geçtikçe daha fazla tercih edilir olmuştur. Alüminyum pasta sadece gazbeton üretim proseslerinde değil, metalik etkili pigmentlerde, plastik sektöründe masterbatch olarak, endüstriyel, dekoratif boyalarda ve otomativ boyalarında yansıtıcı olarak ve daha birçok alanda kullanımı olan bir malzeme haline gelmiştir. Üretim prosesi ve reçeteleri değişikliklere uğratılarak, farklı alanlarda değişik ihtiyaçlara yönelik malzemeler üretilmektedir. Bu tez çalışmasında alüminyum kaynağı olarak hurda alüminyum folyoları kullanılarak üretilen alüminyum pastanın iki farklı doymuş yağ asidi katkısı ile gazbeton malzemeye nasıl etkileri olduğu incelenmiştir. Atık folyo hurdalarının kullanılması bu çalışmanın çevre dostu bir geri dönüşüm prosesi olarak da değerlendirilebileceğini göstermektedir. Böylelikle hammadde maliyeti de azaltılmıştır. Alüminyum pasta kullanımında solvent olarak su kullanılmıştır. Bu sayede çevreye duyarlı, kokusuz ve düşük kimyasal içerikli bir malzeme üretilmiştir. Eşit koşullarda, aynı miktarlarda stearik asit ve palmitik asit kullanarak üretilen alüminyum pasta numunelerinin hidrojen gazı tayini, aktif alüminyum tayini, tane boyut analizi ve yaşlandırma testleri ile kontrollü karşılaştırması yapılmıştır. Ardından bu iki pasta numunesi proseste aynı koşullarda kullanılarak, işletme takibi yapılarak gazbeton üretilmiştir. Üretilen gaz beton numuneleri dayanım, yoğunluk, nem, kuruma büzülmesi gibi gözenekli yapıdan doğrudan etkilenen özellikleri analiz edilerek karşılaştırlmış, ve alüminyum pastanın reaksiyonu sonucu ortaya çıkmış olan makro gözenek yapıları mikroskopla incelenmiştir. Sonuç olarak her iki doymuş yağ asidinin de gaz beton için alüminyum pastada kullanılabilirliğinin olduğu ancak stearik asidin çoğu deneyde en iyi sonucu vererek tercih edilebilir olduğu belirlenmiştir. Projeyi bir adım daha ileri taşımak için özellikle ürünün raf ömrünü arttırıcı bir takım çalışmalarla bu ürüne katkı sağlanabileceği de öngörülmüştür.Autoclaved aerated concrete (AAC) is one of the most preferred building materials for fire safety, heat insulation properties, and most importantly, the safe construction of the buildings located in the earthquake zone of our country, all around the world nowadays. With heat resistance up to 1200 oC, Autoclaved aerated concrete, which is gradedas "A1 class non-combustible" material according to the regulations on the safekeeping of buildings from fire, is best solution for the construction of buildings Many raw materials such as lime, cement, sand, gypsum are used for the production of Autoclaved aerated concrete as input. The aluminum powder, which causes the formation of porous structure and makes increase the volume of Autoclaved aerated concrete, is also very important input with these raw materials. A large part of porous structure of autoclaved aerated concrete is formed as a result of aluminum powder materials that provides not only lightness but also the heat and sound insulation feature to autoclaved aerated concrete. Autoclaved aerated concrete material, which has air pore as 80% of its volume, gains very light weight structure. Although aluminum powder material is so important, it also has serious hazards arising from its use. In the autoclaved aerated concrete production process, the aluminum powder materials have fine grain structure that can be released into the atmosphere produce the hydrogen gas as a result of the reaction. In this way, even if with the smallest trigger (acid, alcohol, oxidizing agents, spark sources) contact with the fine particles, combustion and explosion risks come in sight. It is also uncontrollable fire that may occur, as the fine dust particles that have large surface area trigger each other while burning that spread out to the air. In addition, health issues are realized caused by heavy metal accumulation of aluminum powder in the human body during long-term exposures. The aluminum paste materials have become increasingly preferred day by day as they consist of aluminum source and certain chemical materials, which make the porous structure gain to autoclaved aerated concrete as a building material. Aluminum paste has become an advantageous material because of its easy feeding into the process and safe working conditions. Due to all these reasons, the special material called aluminium paste which contains solvent or water has been used as aluminum based materials in autoclaved aerated concrete production process do not have any risk of dusting and dispersion in the air. Aluminum paste has become a material which is used not only in utoclaved aerated concrete production processes but also in metallic effect pigments, as masterbatch in plastic sector, as a reflector in industrial, decorative paints and automotive paints and in many other fields. Production process and product formulations are subject to changes and materials are produced for different needs in variable areas. In this thesis, effect of aluminum paste products on autoclaved aerated concrete which contain two types of saturated fatty acids by using aluminum foil scraps were investigated. The saturated fatty acids that was used in this study are obtained from both animal fats and plant oils. Saturated fatty acids are straight-chain organic acids with an even number of carbon atoms. There are two types of saturated fatty acids which are stearic and palmitic acids were examined as coating and lubricating material in this thesis. Stearic acid is a fatty acid that is commonly found in nature and has the general chemical properties of carboxylic acids. Almost all types of fat and fat contain a certain amount of stearic acid with a relatively high content of animal fat. Stearic acid is widely used; It is used as emulsifier in pharmaceutical and cosmetic industry, as excipient in textile, accelerator and softener activator in rubber. This material is also used for wax making, crayon making, soap hardening. Stearic acid is used together with glucose in confectionery. It is used to cover metal powders such as aluminum and iron in fireworks. In this study, stearic acid prevents oxidation of aluminum, prolongs the waiting period of the material and prevents the reaction with water by coating. Palmitic acid is another member of the saturated fatty acid group of 16 carbons found in plants and animals. This acid was first obtained from palm oil. Despite its wide distribution, palmitic acid, which is not found in oil in large amounts, generally constitutes 5% of the total fatty acid and is found in 10% of known vegetable oils (peanut oil, soy, corn, coconut oil) and in marine animals. Lard, tallow, cocoa, butter, palm oil contain 25-40% of this component. This acid has good color and oxidation stability. Salts of palmitic acid with alkalis dissolve more in water than salts of stearic acid. Palmitic acid is widely used in cosmetics, wax formulations and waxes. It is also used in the production of these acid emulsifiers, in the production of anionic and nonionic surfactants, in the production of textile chemicals and soap-detergents, as an antifouling agent in foodstuffs. As first step of the study, aluminum paste was prepared with the help of same amount of stearic and palmitic acid at the same conditions then, hydrogen gas determination, active aluminum determination, particle size analysis by particle sizer and aging tests are applied comparatively. After that by using these aluminum paste materials, autoclaved aerated concrete samples were produced with monitoring of process. All the conditions kept constant during manufacturing process. Samples were chosen as aluminum paste, aluminum powder and mixture of aluminum powder and paste materials comparatively. The autoclaved aerated concrete samples for each saturated fatty acids were compared by analyzing the properties directly affected by the porous structure such as strength, density, moisture, drying shrinkage, additionally the macro pore structures were examined by stereo microscope. Also surface area and specific surface area values of samples were determined by BET analyze technique. In the frame of that project, use of waste foil scraps indicates that this study can also be considered as an environmentally friendly recycling process. Thus, the cost of raw materials was reduced by using scrap raw material. Water is used as solvent in aluminum paste production and also lubricating medium for milling process. In this way, environmentally sensitive, odorless and low chemical content material has been produced. As a result, it has been determined that stearic and palmitic acids have the usability of aluminum paste for autoclaved aerated concrete but stearic acid has the best result in most experiments and its preferability is determined. In order to take the project one step further, it is also envisaged that a number of studies that increase the shelf life of the product can contribute to this product.Yüksek LisansM.Sc