Electrical Resistivity of Fly Ash Blended Cement Paste at Hardening Stage

In this study, the effects of fly ash on the electrical resistivity of hardening (setting) cement paste were investigated. Different combinations of water/binder ratio and binder dosage levels were prepared for the mixtures. The fly ash was used in the mixtures by replacing the cement in ratio of 0 %, 10 %, 20 % and 30 % by weight. The measurements were done at room temperature. The relation between electrical resistivity and hydration time with and without electric current application was investigated. The results obtained indicate the influence of fly ash content and water to binder ratio on the electrical resistivity of all the pastes under investigation. As a result, electric current application can be used on the cement paste with high volume fly ash in order to accelerate curing period

Investigation of wear strength of blast furnace slag blended polymer materials

Having symmetrical and balanced material properties, polymer matrix composites are increasingly becoming popular due to easiness of construction and are use in the production of aerospace and automotive structures. In the study, we developed polymer composites based on epoxy resins, containing up to 40 wt.% of blast furnace slag and determined their pin-on-disc dynamic friction, wear, Shore hardness and surface roughness values. Wear tests were performed using a pin-on-disc under dry friction conditions, at the loads of 5, 10, 15 and 30 N, using slip velocity of 0.3 m/s and along distance of 500 m. The hardness and wear resistance values increased with the increase in the content of blast furnace slag. Showing the relationship between wear rate and hardness, an equation with parameters dependent on load was provided. There was an increase in the dynamic friction with an increase in the surface roughness. In addition, dynamic friction was an increasing function of the wear rate. The wear surfaces of the polymer composites were analyzed using scanning electron microscopy. It was observed that the wear rate of the epoxy composites and pure epoxy samples ranged from 19.85 to 171.42 mm /N m. 3TÜBİTAK / 114M15

Tribological Properties of Fly Ash Blended Polymer Composites

In this study, it was studied that the abrasion resistance and characteristics of polymer composites with fly ash (FA). The epoxy based polymer composites are produced with resin and FA as mineral additive. Mixtures of different ratio by replacing the FA were added to the resin from 0 to 30% by weight. Polymeric samples were cured in air conditioning and they were taken from the molds after 24 hours. Polymeric samples gain ultimate strength after 7 days. Therefore, abrasion tests were performed on 7 aged specimens. Abrasion characteristics of polymer composites were defined by pin-on-disc test for 500 m under a dry friction condition and room temperature. Three types of loading conditions were carried out as 5, 10, 15 and 30 N. The hardness and wear resistance values increased with the increase in the content of fly ash. Showing the relationship between wear rate and hardness, an equation with parameters dependent on load was provided. There was an increase in the friction coefficient with an increase in the surface roughness values. In addition, dynamic friction was as a function of the wear rate. The wear surfaces of the polymer composites were analyzed using scanning electron microscopy. It was observed that the wear rate of the polymer composites and pure epoxy samples ranged from 17.82 to 172.96 mm3/Nm.Keywords: Fly ash; polymer composite; characterization; wear; friction.

Zeta potential-viscosity relationship in kaolinite slurry in the presence of dispersants

AKÜ-BAPK / 042.MUH.03Kaolinite is a widely used additive for industrial applications. Hence, the properties of kaolinite affect the quality of the final materials. The fact that kaolinite is a heterogeneous mineral with dual charges has to be taken into account. In this study, the zeta potentials and the apparent viscosities of kaolinite suspensions in water in the presence of three dispersants; sodium silicate, sodium tripolyphosphate and sodium-polyacrylate at pH values of 4, 7 and 10 were determined. Diagrams of zeta potentials (ZPs) and viscosity as a function of dispersant concentration all show minima. The concentrations at which minima of these two properties appear do not coincide, except for those mineral dispersants at high pH values. The results are explained in terms of the spatial distribution of charges on basal and edge surfaces of kaolinite plates in acidic, neutral, and basic media.AKÜ-BAPK / 042.MUH.0

Farklı mineral katkıların epoksi zemin kaplama malzemesinin ıslanmazlığına ve yüzey enerjisine etkisi

Bu çalışmada epoksi esaslı zemin kaplama malzemesinin ıslanmazlık ve yüzey enerjisi üzerine mineral katkı türü ve miktarının etkisi incelenmiştir. Mineral katkı olarak üç farklı atık ürün (uçucu kül, silis dumanı ve yüksek fırın cürufu) ile kireçtaşı kullanılmıştır. Üretilen her bir katkılı ve katkısız epoksi malzemesinin ıslanmazlık özelliğinin belirlenmesinde, damla yayınım (sessile drop) yöntemi kullanılarak su ile temas açıları ölçülmüştür. Epoksi malzemelerin yüzey enerjisi hesaplamaları için ise 3 polar sıvı su, etilen glikol ve formamid ile 1 apolar sıvı diiodometan kullanılarak temas açıları ölçülmüş ve sonra bu temas açısı verilerine göre Fowkes yaklaşımı kullanılarak yüzey enerjileri hesaplanmıştır. Elde edilen sonuçlara göre, mineral katkılar az ya da çok epoksinin ıslanmazlık özelliğini düşürmekte ve buna uygun olarak yüzey enerjisini artırmaktadır. Katkı türleri içerisinde epoksinin ıslanmazlık ve yüzey enerjisi özelliklerine en az etki edenin uçucu kül ve en çok etki edenin ise kireçtaşı olduğu belirlenmiştir.In this study, the effect of type and amount of mineral additives on non-wettability and surface free energy of epoxy based floor coating material have been examined. Three different types of waste products (fly ash, fume silica and blast furnace slag) and limestone were used as mineral additive. Contact angle with water of each produced epoxy material with and without additive were measured by using sessile drop method to determine the hydrophobicity of the materials. For surface energy calculations of epoxy materials, their contact angles first were measured by using three polar (water, ethylene glycol and formamide) and one apolar (diiodomethane) liquid and their surface energies were then calculated according to these contact angles data by using Fowkes approach. Test results show that mineral additives have more or less decreased the hydrophobicity and increased surface energy. It was also determined that in additives fly ash has minimum and limestone has maximum effect on hydrophobicity and surface energy properties of epoxy.TÜBİTAK / 114M15

Effect of mineral admixture type on rheological properties of polymeric self-consolidating mortar

Polimer matrisli kompozitler, simetrik ve dengeli malzeme özelliklerine sahip olmaları, üretim ve kullanım kolaylıklarından dolayı inşaat, hava-uzay yapıları ve otomobil yapıları için popülerlik kazanmaktadır. Günümüzde yeni kullanım alanı oluşturan polimerik malzemelerden birisi de epoksi esaslı kendiliğinden yerleşen harçlardır. Bu harçlar, inşaat sektöründe başta yüzey kaplamaları olmak üzere bina güçlendirmelerinde yaygın bir şekilde kullanılmaktadır. Bu malzemelerin yüzeye uygulanmasında hem yüksek olan maliyetlerinin azaltılması hem de dayanımlarının arttırılması amacıyla atık halde bulunan ve büyük ölçüde çevre kirliliği oluşturan malzemelerin filler olarak kullanımı araştırılmaktadır. Bu çalışmada yüksek fırın cürufu, uçucu kül, silis dumanı, kireçtaşı tozu ve doğal kum kullanılarak üretilen epoksi esaslı kendiliğinden yerleşen harçların viskozite, yayılma çapı ve katılaşma gibi reolojik özellikleri belirlenerek karakterize edilmiştir. Elde edilen deney sonuçlarına göre yüzey alanı yüksek olan mineral katkıların kullanım oranının artmasıyla polimer esaslı harçların işlenebilirliklerini azaltmıştır.Polymer matrix composites are gaining popularity for construction, air-space structures and automobile constructions due to their symmetrical and balanced material properties and their ease of production and use. One of the polymeric materials that make up the new application area is epoxy based self-consolidating mortar. These mortars are widely used in the construction industry, especially in surface coatings in building constructions. Both to reduce the high costs and to increase the strengths of these materials applied to the surface, i t i s bei ng i nvesti gated t he use of t he waste materi al s as a filler which cause environmental pollution. In this study, the rheological properties such as viscosity, spreading diameter and setting of epoxy based selfcompacting mortars produced by using blast furnace slag, fly ash, silica fume, limestone dust and natural sand have been characterized. According to the results of the experiment, the use of mineral admixtures wit h high surface area has been decreased the workability of polymer-based mortars.TÜBİTAK / 114M11

Effect of mixing water types on the timedependent zeta potential of Portland cement paste

The measurement of zeta potential (ZP) has important applications in a wide range of industries including ceramics, pharmaceuticals, medicine, mineral processing, electronics, cement industry and water treatment. It provides new information on cement hydration, gel structure formation and the effects of chemical and mineral admixtures. In this study, ZP and pH measurements of Portland cement suspension prepared at wt % 1 cement/water ratio in the presence of four different types of waters, i.e., pure water, tap water, and salted (NaCl and CaCl ) water, were carried out depending on the time. Also, vicat tests of Portland cement pastes prepared at a water-to-cement ratio of 0.34 were performed. After the vicat tests, X-ray diffraction analysis and scanning electron microscopy investigations were performed on the samples. The most important result obtained from this study is that setting time and time-dependent ZP values of Portland cement paste have different values depending on the used mixing water type. Among the water types, water with CaCl 2 gives the lowest ZP as absolute value, so this leads to minimum initial and final setting times for the cement paste prepared with this type of water.

Investigation of evaluability of marble wastes as a concrete aggregate in Afyonkarahisar zone

Bu çalışmada, Afyonkarahisar organize sanayi bölgesinden temin edilen parça mermer atıklarının “TS 706 EN 12620 + A1 “Beton Agregaları” standardına uygunluğu araştırılmıştır. Atık sahasından alınan parça numuneler standartlarda belirtilen boyutlara getirilerek fiziksel, kimyasal ve yaşlandırma testlere tabi tutuldular. Yapılan testler sonucunda mermer parça atıklarından elde edilen agregaların “TS 706 EN 12620 + A1 “Beton Agregaları” standartlarında aranan alt ve üst sınırlar içinde olduğu ve atıklardan elde edilen agregaların hazır betonda beton agregası olarak kullanılabileceği sonucuna varılmıştır. 7In this study, it was investigated the compliance of “TS 706 EN 12620 + A1 Concrete Aggregates obtained from Afyonkarahisar Organized Industrial Zone. The samples taken from the waste site were brought to the dimensions stated in the standards and subjected to physical, chemical and aging tests. As a result of the tests performed, it is concluded that the aggregates obtained from the marble pieces waste are in the upper and lower limits required by the TS 706 EN 12620 + A1 “Concrete Aggregates standards” and the aggregates obtained from the wastes can be used as concrete aggregates in the ready-mixed concrete

Sol-Jel yöntemiyle borlanmış inconel alaşımının yüzey karakterizasyonu

Bu çalışmada, Inconel alaşımı sol-jel mettodu kullanılarak borlanmıştır. Borlama sonrası numuneler elektrik rezistanslı fırında 900○C'de 1 saat bekeltilerek sinterlemiştir. Numuneler kesitten kesilerek gerekli metolografik işlemlerden geçilirek numunelerin borür tabaka kalınlıkları Nikon MA100 marka optik mikroskop yardımıyla ölçülmüştür. Borlanmış numunelede oluşan fazların analizi Shimadzu XRD-6000 model X-ışınları cihazı yardımıyla tespit edilmiştir. Borlama işlemi sonucunda Inconel 625 alaşımında NiB, Ni2B, Ni3B, Ni4B3, MoB, CrB ve Cr2B fazları elde edilmiştir. Borlama sıcaklık ve süresine bağlı olarak 4.1-9.7 μm arasında borür tabakaları elde edilmiştir. Üç farklı bor bileşiğinde farklı mikro sertlik değerleri elde edilmiştir. Tinkal’de 1673 HV0.1, Sassolit’de 1997 HV0.1, B4C’de 2375 HV0.1, İşlemsiz Inconel 625 alaşımınında ise 541 HV0.1 sertlik değerleri elde edilmiştir.In this study, surface characterization of boronized inconel alloy was investigated by sol gel method. The samples were sintered at 900ºC for 1 hour in a furnace with electrical resistance. The boride samples were cut from the section and the boride layer thicknesses obtained after the required sanding and polishing processes were measured with the help of Nikon MA100 optic microscope. Borate phases were obtained by using Shimadzu XRD 6000 brand XRD device and micro hardness tests were carried out with Shimadzu HMV-2 brand tester. As a result of XRD analysis of boron Inconel samples, NiB, Ni2B, Ni3B, Ni4B3, MoB, CrB and Cr2B phases were obtained. Depending on boron temperature and time, boron layers were obtained on Inconel samples with thicknesses ranging from 4.1-9.7 μm. The micro hardness values of the boronized Inconel samples were 541 HV0.1 in the untreated sample while the hardness values of tinkal 1673 HV0.1, Sassolit 1997 HV0.1 and boron carbide 2375 HV0.1 were obtained

İnce agrega ile yer değiştirmiş olan CaCO3takviyeli ve takviyesiz polipropilenlerin geleneksel beton özelliklerine etkilerinin incelenmesi

Düşük yoğunluk değerine, yüksek ısı ve korozyon direncine sahip olan polipropilen gittikçe yapı malzemeleri sektörü için daha cazip hale gelmektedir. Bununla birlikte polipropilenin tek başına kullanımı yapı malzemesinin mekanik dayanımını düşürmesi bakımından bazı dezavantajlar içerir. Polipropilenin yapı malzemeleri içerisindeki uygulamalarında bu dezavantajın ortadan kaldırılması için polipropilen kompozitleri tercih edilmektedir. Bu çalışmada, CaCO3 takviyeli polipropilen içeren betonun tanımlanan kalite ölçütleri sırası ile termal iletkenlik, elektrik direnci, 3, 7, 28 gün basınç dayanımları, 28 günlük yarmada çekme dayanımı ve su emme oranı olarak belirlenmiştir. Deneylerde ince agrega yerine %0, %10, %20, %30 ve %40 oranlarında CaCO3 takviyeli polipropilen kullanılmıştır. Dolgulu CaCO3/PP takviyeli beton özellikleri kontrol betonu ile kıyaslandığında %34.5 daha düşük 28 günlük basınç dayanımına, %24.7 oranında daha düşük termal iletkenliğe, %50.7 daha yüksek elektrik direncine sahiptir