Repository of the Institute for Material Testing (RIMS)
Not a member yet
1132 research outputs found
Sort by
Geochemical Profiles of Deep Sediment Layers from the Kolubara District (Western Serbia): Contamination Status and Associated Risks of Heavy Metals
No full textGlobal awareness of the harmful effects of heavy metal contamination in soil has increased
significantly. Understanding the vertical distribution of oxides and elements is vital for tracing the history
of potential contamination. Thus, this study focuses on deep sediment cores primarily composed
of quartz and clay minerals from a small village in the western Tamnava Basin of Serbia. The aim was
to assess the vertical distribution of 11 oxides and 21 elements and the ecological risks of eight heavy
metals by analyzing 250 sediment samples from 18 boreholes at depths ranging from 5 to 58.5 m.
Deep sediment core samples were analyzed using energy-dispersive X-ray fluorescence spectrometry
(ED-XRF). Potential contamination levels were evaluated within the study area. Additionally, samples
were analyzed for total carbonate and organic carbon contents and particles retained on a 0.063 mm
sieve. Higher than permitted concentrations of vanadium (V), thallium (Tl), and barium (Ba) were
found. Notably, this zone is located above a proposed lithium and boron mine in Gornje Nedeljice,
making it crucial for monitoring efforts. Even if mining operations do not commence, examining
the deep sediment layers in this rural area remains important. This study offers novel and valuable
data on the concentrations of potentially toxic elements in undisturbed deep sediment, serving as a
benchmark for future comparisons
Značaj otvaranja rudnika „Ćirikovac“ za održavanje i razvoj podzemne eksploatacije uglja u Srbiji
No full textPrediction model for calculation of the limestone powder concrete carbonation depth
No full textThe efficient way to mitigate the impact of the concrete industry on climate change is to reduce the clinker content in the concrete mix. Beside incorporating supplementary cementitious materials (SCMs), it is possible to use high filler content combined with concrete mix optimisation. Limestone powder emerges as a promising filler mineral due to its availability and ready-to-use technology. In this work, the carbonation resistance of concrete with a high limestone powder content (45–65% of the powder phase) was experimentally tested. Test results showed that, with an optimized mix design featuring low water content and increased paste and plasticizer volume, concrete mixes satisfied high workability and strength demands for commonly applied strength classes. However, carbonation resistance remains a challenge. After two years in indoor natural conditions, carbonation depths were 8%, 28%, and 67% greater than referent Portland cement concrete for mixes with 47%, 58%, and 65% limestone powder content, respectively. Further analyses showed the inapplicability of the existing fib Model Code 2010 service life prediction model to limestone powder concrete. Based on a comprehensive database of experimental results, the modification of the fib prediction was proposed. A full probabilistic service life analysis revealed that for concrete with more than 20% limestone powder content and for both 50 and 100-years’ design service life, the currently prescribed concrete cover depths in European standards should be increased, depending on the carbonation exposure class
Developing thermal insulation cement-based mortars with recycled aggregate in accordance with net zero principles
Get PDFThe performance of thermo-insulation rendering mortars with alternations in ratios of powdered cordierite and talc was examined. The goal was to confirm that recycled kilnware cordierite can be reapplied in the mortar design without significant deterioration in performance in comparison with OPC mortar. Differential thermal analysis was employed for examining thermally induced reactions. The cavitation erosion, in testing sequences ranging from 30 to 120 minutes, was used to assess the compactness of the mortar structure. The physico-mechanical properties of experimental mortars were investigated. The morphologies of the mortar tablets upon cavitation were studied using a scanning electron microscope. It was established that cordierite and talc filler in amounts up to 20% enhance microstructural packing and mechanical strengths due to improved cementation and therefore contribute to cavitation erosion resistance. Higher amounts of talc cause structural degradation and mass loss during cavitation tests. Reducing manufacturing costs, energy consumption, and greenhouse gas emissions are the main objectives of the production of this waste-based construction composite, as the reuse of waste materials can help achieve a number of Sustainable Development Goals
Comparison of distributed plasticity approaches for inelastic analyisis of reinforced concrete frames
Get PDFFollowing the emergence and establishment of performance-based design as a widely recognized
and applied practice, numerous significant advances in computational techniques have been
made. Arguably, nonlinear methods of analysis – static or dynamic – provide the most detailed
and accurate insight into behavior of the structure which is designed or assessed. While the
current codes of practice permit their use, provisions are vague in some aspects, leaving many
decisions and assumptions up to the engineer. This paper aims to expand the relatively limited
experience with implementation of different distributed plasticity modeling approaches through
a case study based on experimental data. Some particulars of the behavior of structural elements
made of strain-softening materials, and of their corresponding numerical models, are briefly
introduced. Case study is conducted to provide an overview on the procedures for inelastic
analysis of reinforced concrete frames through a side-by-side comparison of four alternative
approaches for modeling of RC beams and columns with one-dimensional distributed plasticity
finite elements with fiber-discretized cross sections. The analyzed structure consists of a
reinforced concrete column with a fixed base, which is, under varying axial loads, subjected to
monotonic and cyclic lateral displacements applied at its top. Models comprised of force-based
elements with different arrangements of integration points, as well as of displacement-based
elements, are compared. Advantages, limitations and special considerations which need to be
taken into account for each of the approaches are demonstrated through the example. Influence
of concrete confinement is studied by analyzing another column with a different arrangement of
transverse reinforcement. Global structural response is evaluated by comparison of pushover and
cyclic curves for different models. Influence of modeling approach on objectivity of the local
response and the corrections which need to be made for certain approaches are showcased by
moment-rotation curves of the yielded section at the column base. Considerations and findings
presented in the paper, along with other published case studies, can be used for reference when
preparing a computational model for inelastic analysis of a reinforced concrete structure
The influence of rainfall factors on soil resistance to erosion
Get PDFFor the purposes of researching the influence of rainfall factors on soil shear strength, i.e. soil erosion resistance, research was conducted on plots measuring 1.0x0.3 m at a slope of 15°, with equally prepared soil. It’s been carried out 12 rainfall simulations with different values of rainfall factors (rainfall intensity and drops diameter). These simulations were carried out with a modified rain simulator with sprayers by Živanović et. al (2021). The analysis of the uniformity of the prepared soil, as well as the examination of the influence of simulated rainfall factors on soil erosion, was carried out by measuring with a pocket vane tester (Eijkelkamp M1.14.10.E). The measurement was carried out at 30 regularly spaced locations on every plot, immediately after the simulation was completed. Also, the measurement was carried out after 24 hours in three places (upper, middle and lower third of the plot). Spatial distribution of measured values was assessed by Christians' coefficient of uniformity CU. The measured shear strength values of the prepared soil range from 2.1 to 6.9 kN/m2. The shear strength values immediately after the simulation range from 0.4 to 5.4 kN/m2, while after 24 hours they range from 2.4 to 8.1 kN/m2. The CU values of the prepared soil range from 68% to 81% (average 75%). Immediately after the simulation, Cu values range from 73% to 83%, while after 24 hours, from 69% to 91%. In general, there is a clear trend of decreasing values measured with the pocket vane tester from the top to the bottom of the plots. Also, the influence of the change in soil moisture on the values of soil shear strength was observed. The change in rainfall factors affects the change in soil resistance to erosion
Ekološki aspekti proizvodnje građevinskih materijala – ocenjivanje životnog ciklusa proizvoda i izdavanje dozvola za emisiju gasova sa efektom staklene bašte
Get PDFProces evropskih integracija ubrzao je izradu Zakona o klimatskim promenama, koji je usvojen u martu 2021.godine. Ovaj zakon transponuje relevantno zakonodavstvo EU, pružajući pravni osnov za izradu i ažuriranje strategija niskougljeničnog razvoja i programa prilagođavanja na izmenjene klimatske uslove, monitoring, izveštavanje i verifikaciju emisija gasova sa efektom staklene bašte i primenu klimatskih politika i mera. Ocenjivanje životnog ciklusa građevinskih proizvoda omogućava procenu kumulativnog uticaja nekog građevinskog proizvoda ili usluge na životnu sredinu. Imajujći u vidu visoke emisije gasova sa efektom staklene bašte u građevinskoj industriji u radu je data metodologija ocenjivanja životnog ciklusa proizvoda i usluga na životnu sredinu, njihova kvantifikacija kroz izradu deklaracija proizvoda o zaštiti životne sredine, sa posebnim osvrtom na obavezu proizvođača o izradi plana monitoringa i izveštavanju o emisijama gasova sa efektom staklene bašte.Organizatori: Društvo za ispitivanje i istraživanje materijala i konstrukcija Srbije, Institut IMS i Univerzitet u Beogradu Građevinski fakulte
Following the Ancients - Conservation Mortars for the Danube Limes in Serbia
Get PDFSustainable preservation of historic buildings is a long-term process that begins with the analysis of all data related to their creation and further duration and ends with the proposal of measures to preserve their current condition and prevent future damage. In accordance with this, the most important goal of the project Mortar Design for Conservation - Danube Roman Frontier 2000 Years after - MoDeCo2000, was set. Data obtained from the archaeological, architectural, and geological context research with the thorough laboratory testing of sampled Roman mortars along the river Danube in Serbia was used to create valuable proposals for the design of compatible mortar mixtures that could be used for the conservation of the structures in the investigated area
Upotreba recikliranog agregata u Evropi i upotreba u Srbiji, paralele
No full textReciklirani agregat se dobija obradom neorganskog materijala prethodno korišćenog u
građevinarstvu. Upotreba recikliranog agregata postaje sve značajnija sa sve većim
prepoznavanjem potrebe za održivom praksom u građevinskoj industriji. Većina razvijenih
zemalja poslednjih godina aktivno podstiče korišćenje recikliranog agregata razvijanjem
alternativnih tehnologija, podizanjem tehnološke infrastrukture i promocijom korišćenja
sekundarnih sirovina. U Srbiji reciklirani agregat još uvek nije pronašao svoje mesto na tržištu,
niti u građevinskim projektima. Date su neke paralele o mogućnostima korišćenja recikliranog
agregata u Evropi i u Srbiji, uz prikaz podataka o količini upotrebljenog recikliranog agregata,
mehanizmima za stimulisano korišćenje, njegovu promociju i dr
Methodology of stability calculation when the influential parameters are stochastic quantities
No full textWhen using the calculation of stability (regardless of the methodology that is being used), there are two approaches: deterministic and stochastic. The first prerequisite for any calculations is that there are enough data that can be processed statistically – to satisfy the student classification. When using the deterministic method, the main value to be taken into account in the calculations is the mean value, whereas when using stochastic calculations, all the results obtained by laboratory or field examinations are equally represented. Thanks to this, non-homogeneity of the rock mass has been introduced to the calculations. This paper presents the methodology of stochastic calculations, and shows one example of comparative analysis of the results of stochastic and deterministic calculations