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Stabilization of loess with fly ash
No full textTo date, much research has been conducted in the field of the application of fly ash in road construction. Particular attention is paid to the effects of fly ash on soil stabilization. The results of the research show that self - binding fly ash is an efficient and economical stabilizing material for various applications in construction. The aim of this paper is to investigate the efficiency of stabilization of fine-grained soil with fly ash. This paper presents the results of the laboratory test for stabilization of loess with fly ash, which was conducted in August-September 2021 in the Laboratory for Roads and Geotechnics, at the IMS Institute in Belgrade. The materials used are ash from the heating plant "Energetika" doo. from Kragujevac and loess from the project "Nikola Tesla" airport in Surcin
Uniaxial compressive strength test before and after standard fire test on rock mass
Get PDFThe paper presents uniaxial compressive strength test according to SRPS EN 1926. Uniaxial compressive strength test was performed on 12 identical cube-shaped specimen’s dimensions 70 mm x 70 mm x 70 mm, which are made of sandstone. Samples were brought form Laz tunnel and were divided into two groups of six samples. First group of samples consists of 6 samples tested for uniaxial compressive strength. Second group of samples consists of 6 samples exposed to standard fire test according to SRPS EN 1363-1, with the intention to test uniaxial compressive strength after standard fire test. The aim of this study was to examine the uniaxial compressive strength of the rock, before and after standard fire test on the rock mass. The paper presents the strengths of the specimens tested before and after standard fire test
Manganese-pyromellitate complex as a precursor for preparation of spinel Mn3O4
Get PDFIn recent years, thermal decomposition studies of transition metal complexes with
benzenepolycarboxylate ligands have become an area of a great importance due to the possibility of
obtaining useful metal oxides with desirable electrical, magnetic and catalytic properties [1]. As a
contrast to conventional methods for the preparation of metal oxides, such as hydrothermal or sol–
gel treatment, thermolysis is faster, more efficient and environmentally friendly. Mn(II)–dipya
(dipya = 2,2’-dipyridylamine) complex with tetraanion of 1,2,4,5-benzenetetracarboxylic
(pyromellitic, H4pyr) acid, [Mn2(dipya)2(pyr)(H2O)2], has been prepared and characterized by
elemental, spectral and microscopy analyses. Direct thermolysis of the complex up to 1200 °C in an
air atmosphere yielded spinel Mn3O4 oxide material. The obtained Mn3O4 has been characterized
for its structural, spectroscopic, morphological and optical properties. The possibilities of using this
oxide as photocatalyst or co-photocatalyst for removing textile organic dyes, as well as inorganic
pigmentary material, were also investigated and discussed
Mortars of the Roman Frontier on the Danube
Get PDFThe mortars have been always one of the most interesting topics for the researchers of Roman building constructions. The knowledge on this complex building material used in Roman architecture is mostly based on the research of the monumental structures in the territory of today Italy. However, many mortar examinations were executed by the researchers of provincial Roman archaeology as well, who tried to find evidence of the quality of building activities in the provinces. The territory of today's Serbia, except for the existence of scarce studies, was never in the research focus. Even the monumental bridge over the Danube, built at the beginning of the 2nd century that made Trajan’s conquest of Dacia possible, was not researched thoroughly enough when we speak of its building materials. During the last few years, the interest in the Roman buildings at the Danube territory has grown. Mortar Design for Conservation – Danube Roman Frontier 2000 Years after (MoDeCo2000) project is funded by the Science Fund of the Republic of Serbia. Its aim is to investigate the mortars used in Roman buildings along the former Danube Limes in Serbia, as well as to offer mortar recipes for building conservation practice
Geology of Raw Materials in Roman Mortars of the Danube Limes in Serbia
No full textGeological building materials have always played a very important role in the construction of all types of buildings. They were among the first mineral raw materials exploited, processed, and used by man (Prikril et al., 2016). In most cases, these are raw materials of a local character, cheap, and easily available. Accordingly, geological building materials used to make Roman mortars, known for their enviable mechanical properties and durability, played a very important role in the area of the Danube Limes in Serbia. Geologically, this area is built of petrologically different rocks of different geological ages. The rocks formed from the Palaeozoic to the Quaternary contain all the basic geological building materials: sand and gravel, stone, clay, etc
Prednosti i nedostaci korišćenja standarda UL 263 u Republici Srbiji
No full textU radu je prikazana mogućnost primene rezultata ispitivanja otpornosti prema požaru
nenosećeg, montažnog, pregradnog zida bez ispune, debljine 100 mm na zid sa ispunom od
mineralne, kamene vune debljine 150 mm. Prvi zid je ispitan na otpornost prema požaru
korišćenjem domaćeg standarda SRPS U.J1.090, dok je drugi zid projektovan u skladu sa
standardom UL 263. Oba zida su izrađena od materijala sa domaćeg tržišta. Poređenje ispitivanja
otpornosti prema požaru zida je izvršeno radi uskladjivanja projektne dokumentacije urađene u
skladu sa IBC- International Building Code sa domaćim normama. Takođe, u radu je izvršena i
komparativna analiza između ova dva ispitna standarda, kao i standarda koji se odnose na uslove u
peći tokom ispitivanja. Utvrđeno je da se krive razvoja požara temperatuski razlikuju, pri čemu su
stroži uslovi razvoja požara prema domaćem standardu
The comparative analysis of thermal behaviour of a different thicknesses walls made from autoclaved aerated concrete blocks exposed to fire
Get PDFIn this paper a comparative analysis of thermal behavior of six partition walls with different
thicknesses were presented. The walls were dimensions 3000 mm x 3000 mm made from autoclaved
aerated concrete blocks with dimensions 625 mm x 200 mm and thicknesses 50 mm, 75 mm, 100 mm,
120 mm, 150 mm and 250 mm. All walls were exposed to standard fire test according the standard
SRPS EN 834-1, non- combustibility test according the standard SRPS EN 1182 and surface spread of
flame test according to SRPS U.J1.060. All walls were tested to fire resistance in vertical furnace with
a data acquisition system, according to standard fire test. Standard furnace for testing construction
consist of four two step burners in liquid fuel type of 296
kW manufactured by ECO FLAM. Two transmitters of differential pressure type 6321 manufactured
by TESTO (Germany), with range 100 Pa installed inside the furnace were used for pressure
measurement. Inside the furnace the temperature on six places with thermocouple type K were
measures. The measure ranges of thermocouple type K were -2700C to 13720C. The temperatures on
unexposed fire side were measured in nine places with thermocouple type T with measure ranges -
2700C to 4000C of according the national standard SRPS U.J1.090. The obtained temperature results
depending of the time of reaching the critical temperature were presented for each wall thicknesses.
The five identical cylindrical samples with high 50 mm and diameter 45 mm for non-combustibility
test has been used. All samples have been tested in standard furnace for non-combustibility test. The
average temperature in furnace and specimens were presented. Surface spread of flame testing is
carried out according to standard SRPS U.J1.060, if the coating material is based on organic or mixed
materials. The samples for these test are with dimensions 900 x 230 mm
Structure and properties of ZnO/ZnMn2O4 composite obtained by thermal decomposition of terephthalate precursor
Get PDFA biphasic [Mn(dipya)(H2O)4](tpht)/{[Zn(dipya)(tpht)]·H2O}n complex material, I, (dipya = 2,2’-dipyridylamine, tpht2– = dianion of terephthalatic acid) was synthesized by ligand exchange reaction and characterized by XRPD and FTIR spectroscopy. A ZnO/ZnMn2O4 composite, II, has been prepared via thermal decomposition of precursor I in an air atmosphere at 450 °C. XRPD, FTIR and FESEM analyses of II revealed the simultaneous presence of spherical nanoparticles of wurtzite ZnO and elongated nanoparticles of spinel ZnMn2O4. The specific surface area of II was determined by the BET method, whereas the volume and average size of the mesopores were calculated in accordance with the BJH method. The measurements of the mean size, polydispersity index and zeta potential showed colloidal instability of II. Two band gap values of 2.4 and 3.3 eV were determined using UV–Vis diffuse reflectance spectroscopy, while the measurements of photoluminescence revealed that II is active in the blue region of the visible spectrum. Testing of composite II as a pigmentary material showed that it can be used for the colouring of a ceramic glaze
Examination of the physical-chemical and mechanical properties of helical cylindrical compression springs preserved in the Legacy in the Nikola Tesla Museum
No full textThe results of the scientific research work and creativity of Nikola Tesla (Smiljan, 1856 - New York, 1943), a Serbian-American scientist, engineer and inventor, represent the foundation of new technical and technological breakthroughs that began at the end of the 19th century, and without which our everyday life would be unthinkable. The legacy of Nikola Tesla is located in his museum in Belgrade and present unique collection composed from archive documents, different items (personal and technical items) and library (monographies, periodical publications and newspaper clips). The number of original technical items from Tesla's legacy (295 in total) is finite and unchangeable. The collection of items from the field of mechanical engineering consists of 122 different museum artifacts from the following areas: turbo machines, tribology, speed measurement, length measurement, temperature measurement, measuring tools, accessories for technical drawing and writing, machine assemblies and elements, etc. The most numerous groups of objects consist of springs (coil-cylindrical, spiral strip), a total of 30 exhibits. Models of spiral cylindrical springs, depending on how they are loaded, are compression (8 pcs.) or tension type (14 pcs.). The aim of this paper is to present preserved models and to examine the physical-chemical and mechanical properties and contribute with additional knowledge to the Nikola Tesla legacy