Repository of the Institute for Material Testing (RIMS)
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Modifikacija i unapređenje energetsko-disperzivne rendgensko fluorescentne metode za određivanje sadržaja deset elemenata u eluatima cementnih veziva
No full textKorisnik / naručilac: Institut za ispitivanje materijala (Centralna laboratorija za ispitivanje materijala, Laboratorija za veziva, hemiju i maltere)
Analysis of Redistribution of the Pile Shaft-Base Load Using the Dynamic Load Test (DLT)
Get PDFThe paper analyses transmission and redistribution of the load from the pile on the soil, with a special focus on these effects regarding the shaft and base of the pile. The test was conducted using the dynamic load test (DLT) by incrementally increasing the kinetic energy of the drop weight impact in several drops. The results of in‒situ DLTs are presented and after the performed signal matching for every impact of the drop weight. The testing and appropriate numerical analyses determined the mechanism of redistribution of the shaft-base load of the pile up to the ultimate bearing capacity, whereby there occurs a reduction in the transmission of the load via the shaft and an increase in the transmission of the load via the base
Fire protection of health facilities
Get PDFCritical infrastructure can be demaged, destroyed or disrupted by deliberate acts of natural disasters,negligence, terrorism, sccidents or computer hacking, criminal activity and malicious behaviour. When it comes to the protection of critical infrastructure, one of the most important branches which requires protection is the health system.
In the Republic of Serbia, there are no specific technical rules that deal with the fire protection for construction of health facilities. The Rulebook on the protection of residential, business and public buildings from fire partly mentions hospital facilities. Due to the lack of domestic laes designers must rely on foreign laws and regulations.
The paper presents active and passive fire protection that needs to be implemented when designing health facilities and an example of laws used in other countries relating to the fire protection of hospitals.
In addition to active and passive protection of medical facilities buildings it is also necessary to continuously educate both staff and patients to prevent panic attacks and mistakes that may occur due to an inadequate response
Properties of concrete kerbs with recycled aggregate from precast elements
Get PDFThe paper presents the possibility of using recycled aggregate from precast concrete paving elements
and kerbs in the production of concrete kerb units. Experimental work included several types of concrete consistency
class S1, made with different amounts of cement and coarse recycled concrete aggregate. The influence of percentage
and grain size of recycled concrete aggregate on concrete compressive strength at different ages was observed. Based
on the experimental results, it can be concluded that the use of recycled concrete as an aggregate creates a new
composite material that can be used for the production of precast elements. The results show that the replacement of the
coarse natural aggregate with aggregate from crushed concrete is possible to produce concrete curbs that meet the
requirements of EN 1340, but the class depends on the replacement percentage of the natural aggregate with recycled
ones. In this way, the production waste is turned back to process, and the newly created concrete is certainly ecological
material
Assessment of Efficiency of Rare Earth Elements Recovery from Lignite Coal Combustion Ash via Five-Stage Extraction
Get PDFRare earth elements (REE) are frequently referred to as ingredients for enhancements in modem industry, as they are extensively applied in many industrial branches due to their accented electro-magnetic and optical properties. REE have end-utilizations as catalysts, magnets, and as dopants for ceramic materials. Rare earth minerals are scarce therefore the unconventional REE-containing resources such as waste materials and industrial byproducts are continuously being investigated. Coal combustion products comprise REE concentrations varying between 200 ppm and 1500 ppm. This quantity can be isolated though the extraction procedure. In this study, the five stages extraction was conducted on the coal combustion ash from the selected landfill site. The extractions of 32 elements (As, Ga, Ce, Be, Ge, Nd, Cr, Zr, Eu, Cu, Nb, Gd, Co, Mo, Dy, Li, Ag, W, Mn, Cd, Au, Ni, In, Hg, Pb, Sn, Ti, V, Sb, Th, Zn, and La) were conveyed. Chemical analyses were conducted via XRF, ICP-OES, ICP-MS, and MS techniques. The complexity of the obtained data was examined by Principal component analysis and Cluster analysis in order to derive interconnections between quantity of elements and landfill characteristics, as well as mutual relationships among the elements of interest, and to assess the accomplishment of REE recovery from the coal ash
Mechanisms and morphologies of cavitation damage of NN 70 steel
Get PDFPolomljene epruvete za ispitivanje niskocikličnim zamorom čelika Nionikral 70 (NN-70) osnovnog materijala (OM) i simulirane zone pod uticajem toplote (SZUT) poslužile su NAM za izradu uzoraka za ispitivanje otpornosti na kavitaciju. Za ispitivanje u laboratorijskim uslovima primenjena je ultrazvučna vibraciona metoda kavitacije (metoda stacionarnog uzorka). Uslovi i procedura ispitivanja, priprema uzoraka kao i interpretacija rezultata definisani su standardom ASTM G32. Površine uzoraka čelika NN-70 OM i SZUT bile su izložene dejstvu kavitacije i praćenju oštećenja kroz određeno vreme. Merenje gubitka mase uzoraka na analitičkoj vagi posle određenog vremena omogućilo NAM je određivanje kavitacione brzine kao mere procene otpornosti materijala na dejstvo kavitacije. Za praćenje varijacija u morfologiji površine s promenom vremena ispitivanja primenjena je skenirajuća elektronska mikroskopija (SEM). Na osnovu rezultata ispitivanja otpornosti na kavitaciju u radu su analizirane morfologije oštećenja površina za različita vremena izlaganja dejstvu kavitacije uzoraka OM i SZUT čelika NN-70 kao i mehanizmi koji su doveli do oštećenja površina uzoraka.Broken test tubes for low-cycle fatigue testing of Nionicral 70 (NN-70) parent material (PM) steel and simulated heat-affected zones (SHAZ) were used to produce samples for cavitation resistance testing. Ultrasonic vibrational cavitation method (stationary sample method) was applied for testing in laboratory conditions. The test conditions and procedure, sample preparation and interpretation of results are defined by ASTM G32. The surfaces of the NN-70 PM and SHAZ steel samples were exposed to cavitation and damage monitoring over time. Measuring the weight loss of samples on the analytical balance after a certain time allowed us to determine the cavitation velocity as a measure of the material's resistance to the effect of cavitation. Scanning electron microscopy (SEM) was applied to monitor variations in surface morphology with changing test time. On the basis of the results of the cavitation resistance test, the morphologies of the surface damage for different exposure times of the cavitation of PM and SHAZ steel NN-70 samples were analyzed, as well as the mechanisms that led to the damage of the sample surfaces
Application of Non-Destructive Testing for Condition Analysis, Repair of Damages and Integrity Assessment of Vital Steel Structures
No full textLoads at vital steel structures occur during their production and assembly (residual stresses), during the execution of functional tasks in exploitation (stationary and dynamic loads) and during the disturbed process of exploitation (non-stationary dynamic loads). Considering the fact that stress concentrators, corrosion and unpredictable effects that occur during exploitation must be taken into account as well, it is clear that loading of vital structures during the design phase can not be represented with a model in which the parameters change uniformly. Therefore only experimental non-destructive tests performed at large steel structures during exploitation enable the assessment of their current condition, need for particular repairs and assessment of integrity. In that way the data necessary for determination of causes of degradation of material and welded joints at structures, for the evaluation of mutual influence of equipment parts, as well as for determination of functionality and reliability of operation of drive systems. This primarily refers to vital steel structures of bucket-wheel excavators, dredgers and cranes, as well as to vital steel structures at hydroelectric equipment, thermal power plant equipment, bridges etc. This paper presents the analysis of causes for the occurrence of damages at the support structure of the boom of the bucket-wheel excavator, which is operating at the open pit coal mine near Kostolac (Serbia), that was executed on the basis of non-destructive tests. The paper also contains the procedure for the repair of damaged structure through the application of adequate welding, performed at existing and newly produced components, and the assessment of structural integrity after the repair based on non-compliances detected during the design process, as well as during the making of the support structure of the bucket-wheel excavator boom due to inadequate radiuses defined during the processes of design and production and due to the existence of flaws on the surface and within welded joints
Comparisson between damage development on composite and standardized mortar specimens exposed to soluble salts
No full textSalt crystallization of lime-based rendering mortars is one of the most common reasons for their deterioration. Still, testing of the resistance to soluble salt action has not yet been standardized for this type of material. Lime-based renders are usually placed in several layers, each of them having a specific role and composition. Nevertheless, tests used in the literature are commonly performed on standardized prismatic or cylindrical mortar specimens. This paper presents a comparison between damage development on the composite samples, prepared on porous stone substrate with two types of rendering mortars, and standardized prismatic mortar specimens. Samples were prepared with pure putty lime mortars and lime-putty based mortars with the addition of natural zeolite. Two types of composite samples and four types of prismatic samples were used during the test. The testing was conducted at the age of 90 days using two types of salt solutions (NaCl and Na2SO4). Damage development was followed visually during five cycles of wetting and drying. Salt distribution using XRF analysis was measured at the end of the test on composite samples. It was shown that damage development greatly depends both on sample and mortar types
