Institute IMS

Belgrade, Serbia

Institute IMS

Belgrade, Serbia
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Nikolic D.,Institute IMS | Bojovic D.,Institute IMS | Jankovic K.,Institute IMS | Loncar L.,Institute IMS
fib Symposium PRAGUE 2011: Concrete Engineering for Excellence and Efficiency, Proceedings | Year: 2011

The mechanica) properties (compressive strength and flexural strength) were investigated under different curing conditions (standard and steam curing). Silica fumes have characteristics that make them necessary in cement composites with ultra strength properties. The search for substitute products thus appears important if the use of ultra high performance concrete (UHPC) is to become more widespread in the concrete industry. Possibilities of getting ultra high performance self compacting concrete (UHPSCC) with materials available in Serbia, based on experimental work are discussed in this paper. Four series of samples were made with different types of fine reactive additives (silica fume in referent concrete was replaced with metakaolin at 20% and 40% and with fne fly ash at 20%.). The produced mixes had self compacted consistency. The compressive strength varied between 145 and 180 MPa for the steam cered specimens and between 180 and 205 MPa for the ones that had not been heat treated. Furthermore, this paper presents SEM micrographs of C-S-H phase formed after steam curing and autoclaving.

Mladenovic G.,University of Belgrade | Cirilovic J.,Institute IMS | Queiroz C.,University of Belgrade
Transportation Research Record | Year: 2011

This paper presents the application of the World Bank's Road Network Evaluation Tools (RONET) model to strategic network-level analysis of the Serbian state low-volume road (LVR) network. This network condition deteriorated considerably during the 1990s as a result of the under-financing of its operations and maintenance. In recent years, financing for the road sector has gradually increased and focuses on the most hazardous and highly trafficked parts of the network. However, the overall budget allocated to the sector remains inadequate to maintain the entire state road network in stable condition. The goals of the presented study are to obtain the optimum maintenance and rehabilitation (M&R) strategy and related budget, estimate the impact of different funding levels on future quality, and estimate the economic consequences of budget constraints for the M&R of the LVR network. Application of the RONET model to the prevailing conditions on the Serbian LVR network led to an optimal M&R strategy with a good balance between rehabilitation and periodic and recurrent maintenance. Implementation of the optimal M&R strategy would cause major improvement compared with the current condition of the LVR network. Implementation of higher M&R standards would lead to substantially higher road agency costs and, consequently, lower net benefits, whereas the implementation of lower M&R standards would lead to considerably worse network condition for approximately the same or slightly lower agency costs. This situation means that even minor budget constraints would result in considerably worse network condition and much higher total road transport costs.

Atanasovska I.,Serbian Institute Kirilo Savic | Mitrovic R.,University of Belgrade | Momcilovic D.,Institute IMS | Subic A.,RMIT University
Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science | Year: 2010

This research investigates the effects of the nominal load value on load distribution of simultaneously meshing gear teeth pairs, and on the involute gear load capacity. The research results presented in this article confirm that the nominal load value has a significant influence on the gear load capacity calculations. However, this influence is generally neglected in standard gear calculations, which can result in oversized gear dimensions. This can lead to inadequate gear designs in practice due to increased demand for reduced gear size and weight in modern machinery. The article provides a detailed description of the iterative numerical method developed in this research to support the modelling and analysis of load distribution in meshed gears using the finite-element method. © Authors 2010.

Bleiziffer J.,Institut IGH d.d. | Balagija A.,Institut IGH d.d. | Milovanovic N.,Institute IMS | Barisic E.,ASCON Institute | Jokanovic M.,Institute IMS
Dam Maintenance and Rehabilitation II - Proceedings of the 2nd International Congress on Dam Maintenance and Rehabilitation | Year: 2011

After more than thirty years of exploitation within the project of reconstruction and modernization testing and condition assessment of civil structures was conducted. Performed works included twelve structures of HPP: dam body with galleries and shafts inside, stilling basin, intake structure with valve chambers, headrace tunnels, powerhouse and transformer premises, draft tubes, lower surge tank, tailrace tunnel, grouting galleries and 220 kV switchyard. It pertained to assessment of condition of concrete structures, metal and steel structures and elements, dam monitoring instruments and execution of geological-engineering maps. Specialist services, rendered by climbers and divers were used and dewatering and cleaning of stilling basin was done to perform the inspections and the tests in areas hard to reach. © 2011 Taylor & Francis Group, London.

Jankovic K.,Institute IMS | Romakov Z.,Institute IMS | Bojovic D.,Institute IMS | Nikolic D.B.,Institute IMS
Tehnicki Vjesnik | Year: 2011

Reconstruction of Northwest breakwater in the Tripoli Harbour - Libya (about 4500 m long) required manufacture of various concrete elements (cubes and accropodes) in total amount of 550 000 m3. Volumes of cubes were 6,3 m3,8,5 m3and 12,7 m3, volumes of accropodes were 6,3 m3 and 9,0 m3. After preliminary trials and trial production, an optimum mix proportion was chosen, in compliance with technical specification requirements. One of the main causes for concrete blocks cracking is the temperature difference between core and external surface of the blocks, so new blocks with new mix proportions were made (three variations in cement content). Temperature was measured at three characteristic points: In the middle of the cube, in the middle of vertical outer surface and in the middle of horizontal upper edge. Finally, optimal proportions of the constituent materials were adopted.

Slovic Z.,Key to Metals D.o.o. | Nedeljkovic L.,University of Belgrade | Raic K.,University of Belgrade | Odanovic Z.,Institute IMS
Kovove Materialy | Year: 2012

The correlations between the sulphide capacity and the optical basicity models available in literature are reviewed. The relationship between sulphide capacity and the optical basicity was investigated on plant data collected from the BOF plant in the temperature range of 1565- 1650°C. The goal of this work was to compare results given by applying common acceptable Young's, Sosinsky-Sommerville's, Tsao-Katayama's and Taniguchi's optical basicity as well as the KTH model for calculating the sulphide capacities. The present paper is focused on the thermodynamic aspect of sulphur refining CaO-Al 22 3-SiO 2-MgO ladle slag during LF ladle treatment. Thirty one heats were employed in the present study in real production conditions of low carbon steels.

Mitrovic A.,Institute Ims Ad | Nikolic D.,Institute IMS | Milicic L.,Institute IMS | Bojovic D.,Institute IMS
Tehnicki Vjesnik | Year: 2013

Metakaolin composite cements were prepared with 5 to 35 % replacement of ordinary Portland cement with metakaolin (MK), manufactured by thermal activation/calcination of domestic kaolin clay, and commercial matakaolin (CMK). Performance of the composite cements was evaluated through the setting time (initial and final), compressive strengths (for ages 2, 7, 28, 90 and 180 days) and soundness, and compared with control cement (Portland cement - CEM I). After 28 days, compressive strength was higher than that for control cement for cements prepared with addition of CMK, and with addition of up to 25 % MK.

The sensitization degree of austenitic stainless steel welded joints was investigated by electrochemical methods of the double loop electrochemical potentiokinetic reactivation (DL EPR) in H2;SO4; + KSCN solution, and by the measurement of corrosion potential of the steel in the drop of the solution of HNO3; + FeCl3; + HCl. The welded joints were tested by X-ray radiographic method in order to check the presence of the weld defects. The grain sizes of the base metal and the welded joints were determined by optical microscopy. Good agreement between the results obtained by different electrochemical methods was obtained. The heat-affected zone (HAZ) of the austenitic stainless steel welded joints has shown a significant degree of sensitization. The double loop electrochemical potentiokinetic method gave quantitative evidence about the susceptibility of stainless steel to intergranular corrosion.

Dobric J.,University of Zagreb | Markovic Z.,University of Zagreb | Budevac D.,University of Zagreb | Flajs Z.,Institute IMS
Gradjevinar | Year: 2015

Stainless steel has a number of features that define different behaviour of structural elements made of this material, as related to equivalent carbon steel elements. These properties, especially prominent in case of compression elements, are manifested through the nonlinear stress and strain relationship, pronounced influences of material hardening due to cold forming. Basic principles for the analysis of coldformed stainless steel compression elements, either included in modern technical regulations, or resulting from current research, are presented in this paper.

Cocic M.B.,University of Belgrade | Logar M.M.,University of Belgrade | Cocic S.L.,Institute IMS | Devic S.S.,Institute IMS | Manasijevic D.M.,University of Belgrade
JOM | Year: 2011

This work presents the results of investigation process of copper concentrate roasting in fluidized bed reactor with the aim of studying the transformations of copper concentrate minerals as well as to check the accordance with theoretical predictions. The roasted samples were examined using chemical analysis, x-ray diffraction, and mineral microscopy.

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