Metin Davraz

Determination of Radiation Shielding of Concrete Produced from Portland Cement with Boron Additives

Concrete is a material which is widely used for neutron shielding in such building constructions as nuclear power stations, particle accelerators and medical hospitals. Concrete is very significant for neutron shielding, because is contains some elements which help to moderate very penetrative fast neutrons. Boron increases the neutron shielding effectiveness of concretes. Boron can be added to concrete in different ways, by addition of boron to the water, used in concrete, or by addition of boron containing natural minerals. In this study, three samples of concrete were produced using B2O3 additives material, boron-modified active belite and Portland cement. Neutron absorption coefficients of the produced three different types of concrete samples were obtained through experiments. It is concluded that the addition of boron to concrete is an alternative option to be used for the purposes of neutron shielding.

Performance properties of vacuum insulation panels produced with various filling materials

Abstract Vacuum insulation panel (VIP) is known to be the most effective insulation material. However, the usage areas of VIPs are restricted because of their high production costs. The core of VIP is the most important item affecting the cost of VIP. In this study, to obtain VIPs, which are provided with minimum thermal conductivity resistance value (R=5 m2 K/mW), was aimed for the optimal thickness of the panel (<40 mm). Therefore, 14 different core samples of VIP were produced by using various types of powders (fumed silica, precipitated silica, perlite, and diatomite), opacifiers (silicon carbide, carbon black, and titanium dioxide), and fibers (glass fiber, organic fiber, and cellulosic fiber). By using appropriate test methods, the physical properties of core samples such as unit weight, porosity, mass per volume and mechanical properties, their uniaxial compressive strength, tensile strength, and dimensional stability and also thermal conductivity coefficient in vacuum were determined. Results were compared with values of reference materials. The most appropriate compression pressure used in the manufacture of core sample was 27.5 kN. In addition, taking into account the benefit-cost relationship, the results of this study showed that the mix of fumed silica and precipitated silica (powder material), silicon carbide (opacifier), and glass fiber (fiber) was determined as the most suitable raw materials.

POMZA AGREGALI KÖPÜK BETONLARIN ÖZELLİKLERİNİN ARAŞTIRILMASI

Volkanik faaliyetler sonucu olusan pomza, gozenekli ve iceriginde kristal suyu yer almayan bir kayactir. Gozenekli olmasi sebebiyle kullanildigi alanlarda, isi ve ses gecirgenligi yonunden avantaj saglamaktadir. Ayrica gozenekli oldugu icin de hafiftir. Pomzanin hafif olmasi, isi ve ses yalitim ozelliklerinin iyi olmasi nedeniyle insaat sektorunde cesitli yapi malzemelerinin uretiminde kullanim alani bulmaktadir. Buna ragmen, pomzanin insaat sektorunde yaygin kullanilan geleneksel yapi malzemelerine gore kullanim orani oldukca azdir. Bunun sebeplerinden biri ise ulkemizde bulunan bu dogal kaynakla ilgili yeterli akademik calismalarin olmamasidir. Bu calisma kapsaminda; Isparta, Kayseri, Nevsehir ve Karaman pomzalari kullanilarak kopuk beton uretilmistir. Ayrica, pomza agregasi yerine tas unu (kirectasi) kullanilarak kontrol betonu da uretilmistir. Toplamda deneysel uygulamalar icin 5 farkli kopuk beton uretimi yapilmistir. Uretilen kopuk beton numunelerinin birim hacim kutle, basinc dayanimi, isi iletkenlik katsayisi, ses yutma katsayisi ve ses iletim kaybi degerleri belirlenmistir.

Investigation of Properties of Foam Concretes Produced Using Pumice at Different Ratios

Foam concrete is a type of light weight concrete having self-compacting properties. It can be obtained by mixing the foam, formed by the foaming agent, with a mixture consisting of cement, water and aggregate. It contains independent closed pores with a volume of 75–80% within its body. In this study, three series of foam concrete were produced using different ratio of pumice. Compressive strength, splitting tensile strength and thermal conductivity of foam concrete samples were determined for each density set. It is found that, pumice ratio has a linear relationships with dry bulk density, compressive strength, tensile strength and thermal conductivity. It can also be concluded that strong relationship exist between higher correlation coefficients and pumice ratio.

A Different Product in Thermal Insulation

Although recently searching devoted to the alternative energy sources increases in our country having limited energy sources based on fossils, important steps were extended to save energy by applying the effective precautions. Hence, the effective thermal insulation applications have speed up especially in new constructions. Thermal insulation products such as EPS and XPS polystyrene foam, glass wool and rock wool etc. are commonly used in our country. In addition to this, European Community Directives were become valid and the new arrangements were made in our relevant national laws based on these directives. After these arrangements, thermal insulation performances of these types of materials gain much more important. Also, the technical properties of these materials such as fire resistance, compressive strength, capillarity, water vapor permeability and sound absorption are the considerable facts, too. This case caused acceleration to new investigations for both improving the current thermal insulation product properties and developing new insulation materials. In this paper, pre-inventions of a thermal insulation material with high performance, long service life, economic and easily applicable carried out in SDU Pumice Research and Application Centre are discussed in detail. This research material is actually an inorganic based plaster. This plaster proves the suggested technical properties in TS EN 998-1 and is a lightweight aggregated plaster in “T Category” according to this standard. Physico-mechanical analysis results of samples casting in laboratory conditions were evaluated according to TS EN 998-1. In respect to this, the developed plaster indicates basically these technical properties; T1 category thermal insulation class, Aiƒ—1 class of fire resistance and non-combustible, CSiƒ—I - CSiƒ—II class compressive strength, Wiƒ—0 class capillary water permeability, low water vapor diffusion resistance, high adhesive strength and easily applicable any type of surfaces. Key Words Lightweight aggregate, inorganic binding, high thermal insulation, foam plaster