Karayolu Esnek Üstyapı Binder Tabakasında Elektrik Ark Oocağı Cürufunun Yapay Agrega Olarak Kullanımının İncelenmesi

Abstract

Türkiye, Dünya genelindeki ham çelik üreticileri arasında önemli bir yerde bulunmaktadır. Yıllık üretim miktarı ile en büyük ham çelik üreticileri arasında ilk 10 içinde olan Türkiye'de, 2013 yılında üretilen 35 milyon ton ham çeliğin 24 milyon tonu elektrik ark ocağı kullanılarak elde edilmiştir. Ülkemizde üretilen ham çelik büyük ölçüde hurda metalin geri dönüştürülmesine dayanmaktadır. İç piyasa imalat için gereken hurda çelik talebini karşılayamaması nedeniyle, Türkiye'nin 2013 yılındaki hurda çelik ithalatı 24 milyon ton olarak gerçekleşmiş ve Dünya'nın en büyük hurda çelik ithalatçısı olmuştur. Ülkemizde hurda çelik bu denli önemli bir şekilde geri dönüştürülerek ekonomiye kazandırılmasına rağmen, çelik üretiminde yan madde olarak ortaya çıkan cüruf değerlendirilmeden stok sahalarında depolanmaktadır. Günümüze kadar depolanmış cüruf miktarının 100 ile 140 milyon ton arasında olduğu tahmin edilmektedir. Yapılan bu çalışmada, elektrik ark ocağı cürufunun, karayolu esnek üstyapısının binder tabakasında hammadde olarak kullanılabilirliği incelenmiş ve yapay agrega olarak değerlendirilebilirliği üzerinde çalışma yapılmıştır. Çalışmanın ilk bölümünde, çalışmanın amaçları ve gerekliliği, ülkemizde demir çelik sektörü ve inşaat sektörü hakkında genel bilgi verilmiştir. İkinci bölümde karayolu üstyapı tabakaları ele alınarak açıklamalarda bulunulmuştur. Üçüncü bölümde esnek üstyapı tabakalarında kullanılan agrega ve bitümlü bağlayıcılar hakkında bilgi verilmiş ve Karayolları Teknik Şartnamesi 2013'e göre kullanılması istenen bu malzemelerin fiziksel ve mekaniksel özelliklerine ilişkin yeterlilik koşullarına yer verilmiştir. Dördüncü bölümde demir çelik üretimi ve üretim yöntemleri yer almaktadır. Üretim yöntemlerine göre ortaya çıkan farklı tür cürufların oluşumu hakkında bilgi verilmiş ve oluşan cürufun depolanması açıklanmıştır. Beşinci bölümde farklı yöntemler sonucu oluşan demir çelik cüruflarının fiziksel ve kimyasal özellikler açıklanmış ve diğer ülkelerdeki değerlendirilme alanları hakkında bilgiler verilmiştir. Altıncı bölümde, bu çalışmada kullanılan bitüm, doğal agrega ve elektrik ark ocağı cürufu hakkında bilgi verilmiş, çalışmada kullanılacak yöntemler açıklanmıştır. Çalışmada kullanılan malzemelerin özellikleri, Karayolları Teknik Şartnamesi 2013 Kısım 407 Asfalt Betonu Binder ve Aşınma Tabakaları başlığı altında belirtilen agreganın fiziksel ve mekanik özellikleri kriterlerinin sağlanıp sağlanmadığı yapılan deneyler ile kontrol edilmiştir, bunun yanı sıra kullanılan bitüm için de penetrasyon deneyi ve özgül ağırlık deneyleri yapılmıştır. Doğal agrega ve EAO cürufu agregası ile karışım tasarımı yapılmış, yöntem olarak Asphalt Institute MS-2 kitabında açıklanan Marshall Tasarım Yöntemi kullanılmıştır. Yedinci bölümde doğal agrega ve EAO cürufuna uygulanan deneyleri, Marshall Tasarım Yöntemi ile ulaşılan sonuçlar ve belirlenen optimum bitüm yüzdesi değerleri hakkında bilgi verilmiştir. Çalışmanın son bölümünde bu çalışma kapsamında elde edilen sonuçlar değerlendirilmiş ve önerilerde bulunulmuştur.

Consumption of raw material is increasing day by day and in a limited environment, it is almost sure that in the future sources of raw materials will expire. Especially during the rapid industrialization era, it has been realized that the way people use natural resources, had an immense harm on the nature. Need of new resources resulted people to invade more wildlife areas and urbanize rural lands. All of the damaged caused by people has started to show its effects in the 20th century. Since late 1970's, recycling and reprocessing of disposal materials have been an important subjects in developed countries. Reusing a waste material does not only decrease the necessity of using natural resources but also increases the economic benefits of used material. Decreasing the demand also reduces the production costs by lowering costs of input materials and also there might be additional utilities that can not be acquired by traditional resources. Some of studies have focused on reusing industrial disposals. The reason why it's been researched thoroughly is because of the countless amounts of produced waste materials. By reusing primary disposal industrial materials, significant benefits are being claimed. The main reason of the importance is, these materials are being produced continuously. Retrievaling waste material may decrease the production costs, increase the efficiency and reduces the usage of raw materials, more importantly growth of disposal areas could be avoided. In this thesis, the usage of electric arc furnace slag was investigated in road construction. Turkey is the 8th biggest steel manufacturer in the world and every year 35 million tons of steel has been produced. 24 million tons of the total production is being made in electric arc furnaces and due to the way steel is produced, slag production is inevitable. According to studies, it is estimated that every year 3 to 4 million tons of electric arc furnace slag is obrained by manufacturers and stocked in storage areas. Total amount of 100 to 140 million tons of slag is currently occupying valuable free lands and accumulating over the time. In overseas countries blast furnace slag and steel slag are being used in different applications but in Turkey there isn't any beneficial reuse of slag. Steel production by an electric arc furnace is the most common method in Turkey. It was so much used that in 2013 Turkey was declared as the biggest scrap steel importer. The purpose of this study is to investigate electric arc furnace slag as an artificial aggregate in road construction. By researching the availability, it is expected to reduce stocked waste materials of steel industry, reduce the demand of natural materials and gain economic benefits. Reducing the demand of natural resources would help to save the nature, the wildlife and the ecosystem, which is highly interrupted in Turkey. The aim of the study is to ensure the usage of electric arc furnace slag in Turkey, so that applied tests and decisions were made according to the requirements described in The Technical Specification of Highways 2013 published by General Directorate of Highways. The study was focused on using electric arc furnace slag in a binder course of flexible pavements as an artificial aggregate. To being able to make a decision, the current method of building a road with natural aggregate was used for a comparison against the one built with steel slag. Compared examples had been made by using the Marshall Test Method described in Asphalt Institute MS-2 Asphalt Handbook and tested according to defined procedures. In the first section of this study, general information about the steel industry in Turkey was introduced and the link between the steel production and slag was explained. The amount of slag produced by the steel industry according to statics was stated and slag treatment processes in Turkey were explained. According to given information the purpose, the scope and the importance of this study were given. In the second section, brief information about different pavement types was given which are rigid, composite and flexible. For rigid and composite pavements, various application types were explained. Using of rigid and composite pavement purposes and advantages were mentioned. For flexible pavements, the investigated subject of this study, detailed information was given by introducing each layer (subgrade, subbase, base, binder and wearing courses). In the third section, more information about flexible pavements was given in relation to the purpose of this study. Materials that are used to build a flexible pavement, like bituminous materials and aggregates, were briefly explained. For each layer of the pavement, the required specifications of the each material according to Technical Specification of Highways 2013 were given. In the fourth section, iron and steel productions were explained. For iron production, sources of iron and the production in a blast furnace were described. Steel productions by methods (basic oxygen furnace and electric arc furnace) were briefly explained. For each type of furnaces, production process was explained. Slag productions due to iron and steel productions were introduced, types of slags were explained and the treatments of produced slag for different furnaces were mentioned. In the fifth section, for different types of slags, physical structures occurred by cooling methods were briefly explained. Also chemical compositions and physical properties were mentioned. Addition to slags' specifications, alternative usages of slag were described. Various applications and benefits of using slag as an input material were explained. In the sixth section, firstly, materials used in this study were introduced. Performed tests for natural aggregate and steel slag that are supposed to determine physical properties were mentioned. Tests for bitumen used in the study were applied as well. For each test method, required test standards and followed procedures were briefly explained. Secondly, the design method for binder layer used in this study, Marshall Test Method described in Asphalt Institute MS-2 Asphalt Handbook, was explained. Test procedure was mentioned and necessary calculations in order to make a pavement design were given. In the seventh section, results of tests for determining the specifications of materials that had been described in the sixth section were given and comparisons with required specifications stated in The Technical Specification of Highways 2013 Section 407 Asphalt Concrete Binder and Wearing Courses. Data obtained from Marshall Test Method was given and drawn graphics according to different mixtures were plotted. Each graphic was described briefly. In the last section of this study, electric arc furnace slag as an artificial aggregate was evaluated. The evaluation was made in two sections. Firstly general pros and cons for steel slag as an artificial aggregate was mentioned then for the given optimized asphalt content for each material, calculated results were compared and suggestions were given.