Repository of the Institute for Material Testing (RIMS)
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Cement zasnovan na bio-otpadu za održivu građevinsku praksu
No full textIndustrial byproducts are being increasingly used as raw materials in the cement clinker production. This can help to address the issue of huge amounts of eggshell waste that are discarded into the environment. This bio-waste has a trigonal-calcite structure and similar behaviour as limestone. In this study, cement clinker is synthesized at 1300 °C using eggshell waste in place of limestone. The raw materials are mechanically activated in a high-energy mill. The sintering kinetics are calculated using the results of differential ther-mal analysis. Mechanical activation modified the spatial distribution of Al, Si, Ca, and Fe, thereby improving the reactivity which in turn decreased the sintering temperature of the clinker. The study demonstrated that eggshell waste is a suitable replacement for limestone in the production of ordinary Portland cement
Techno-economic analysis in the service of traditional ceramic industry. The first review
No full textThe traditional ceramics industry uses large amounts of
raw materials and energy while significantly contributing to
the CO2 footprint. The improvements, primarily in the first
two areas, will contribute to sustainable development and
answer the emerging questions of decreasing a gas-release
footprint. These are topics of high importance considering
European Union goals, and thus, on the contrary, there is yet
only scarce available literature on the subject. This paper
describes the state and future perspectives of the traditional
ceramics industry through the techno-economic lens. Many
options are detected that save resources (waste materials),
energy consumption (reparation or modification of kilns,
usage of dry pressing in ceramic tiles production, etc.), and
control of flue gas composition (changing the fuel, etc.).
Further intensified research is needed to widen the knowledge and compare the results. In the first place, the composition of flue gas should be determined by the same
methods and presented using unified units. The lowest energy
consumption and flue gas composition are determined in
ceramic tiles production by the dry route. Using a downdraft gasifier of biomass in brick manufacturing increases
the internal rate of return if a longer tunnel kiln is applied.
The expected payback period is from 4 to 8 years
The innovative method for determining the approximate value of the Bond work index
No full text: In this study, we examine an innovative approach to determining the Bond work index, a key parameter in the mining and cement production industry that indicates material grindability. The method relies on the first-order kinetics law and allows for the estimation of approximate index values with any number of grinding cycles, depending on the desired data accuracy. An important aspect of this approach is the multiplication of parameters G and P80 for each cycle by specific coefficients, achieving values close to those of the last grinding cycle when equilibrium is reached in the standard test. In this paper, we compare the results obtained by the innovative method with the standard Bond procedure on various samples of mineral materials. Our analysis shows a significant reduction in the mean square error as the number of grinding cycles increases, indicating increased precision of the new approachhttp://www.serbianceramicsociety.r
Experimental Investigation of Elastic Modulus of Ultra-High Performance Concrete on Small-Scale Specimens
No full textModulus of elasticity of concrete and other cement-based materials is experimentally obtained through a static load test, which generally involves cyclic preloading in the elastic range, before recording the final measurements of force and deformation. Due to heterogeneity of concrete, certain minimal size of a specimen is needed. This requirement is addressed in relevant standards, where specimen sizes are prescribed. Ultra-high performance concrete (UHPC) mixes contain fine quartz aggregates, which may permit a smaller specimen size, such as those used with mortars, which would reduce costs and waste associated with laboratory testing, while retaining satisfactory confidence in results. In the investigation presented in the paper, testing procedure for concrete was modified to accommodate a smaller specimen size (40x40x160mm prism) and used to obtain the stabilized elastic modulus of three UHPC mixes with varying amount of steel fiber reinforcement. The results exhibit a relatively small dispersion and a reasonable agreement with dynamic moduli obtained by pulse velocity method. To validate the results, a numerical investigation is carried out to examine the influence of imperfect specimen geometry on strain readings. Technical aspects of the testing method, potential improvements and prospects of application to other fine-grained cement-based materials are outlined and discussed.http://www.serbianceramicsociety.r
Electromagnetic property selection for GPR modelling in corrosive concrete environments
No full textUnderstanding the mechanisms that alter the ground penetrating radar (GPR) electromagnetic wave propagation as a result of reinforcement corrosion is pivotal for accurate assessment of the corrosion of reinforced concrete (RC) structures. Nevertheless, the behaviour of the GPR signal during the complex corrosion process is not thoroughly understood. In this study, finite-difference time-domain (FDTD) modelling was used to analyse the effects of corrosion-related parameters, i.e., moisture, chlorides, and corrosion products, on the electric field strength. This study aims to expand the database on numerical simulations of GPR signal behaviour in corrosive environments. It also addresses the knowledge gap in modelling the frequency-dependent properties of concrete and iron oxides. Modelling approach adopted in the study was validated with experimental data obtained on laboratory specimens that correspond to the numerical models in terms of geometry and condition
Additional tool for pull out test: Polymer samples with brass nuts
No full textThis study describes a specialized aluminum tool for holding and testing thermoplastic samples, see
Figure 1. The tool was fabricated using conventional machining processes (lathe, milling machine), while the
samples were produced using additive manufacturing, specifically the Fused Deposition Modeling (FDM)
printing process. The lower part of the tool is secured to the stationary clamp of a tensile testing machine,
while the upper part holds and secures the sample. A threaded insert is installed and secured to the movable
clamp equipped with a sensor. The samples are made of Polylactic acid (PLA) as a cuboid (dimensions 20 x 20
x 4.1 mm) with embedded brass inserts. Conceptually, the tool is an auxiliary device on a tensile testing
machine for evaluating the maximum axial pull-out force, see Figure 2. A standard pull-out test is based on a
load introduced via a screw or threaded rod.Eighteen samples were produced and tested. It was determined that the insert geometry, the bonding
technology between the insert and the plastic, and the printing parameters significantly influence the joint
strength. Six sample combinations with variations were tested, respectively: layer height (0.3 mm), wall
thickness (0.8/1.2/1.6 mm), wall line contour (2/3/4), and top and bottom layer number (2 and 4). Many
samples failed due to the metal insert fracturing the internal and surface bonds within and around the hole.
Delamination between the printed layers was also visible on the fracture cross-section. The tensile force
transferred to the contour of the hole wall, and shear stress appeared at the interface between the infill and
the wall line contour. Based on the results and the defined print combinations, the following tensile forces
were obtained, respectively: 90, 111, 121, 213, 247, and 269 N. Generally, during this test, the inserts failed
with an attached cylindrical material fragment torn from the thermoplastic inserts, see Figure 3. It can be
concluded that the contour of the top and bottom layers does not significantly impact when considering the
axial pull-out force. The pull-out force is higher when more contour lines are around the defined hole.
Additionally, the joint strength was significantly improved with a higher layer height value, regardless of
the variable wall thickness and wall contour values. The maximum layer height of 0.3 mm proved to have a positive impact on the maximum pull-out load. The results obtained in this study can be helpful for further
research in the realization of other connection types. Other thermoplastic composite materials with
improved mechanical properties should be included in future research
Application of waste raw materials as a reinforcement for protective coatings based on pyrophyllite
No full textIn this study, pyrophyllite was used for the first time in the composition of protective refractory coatings together with supplementary waste resources. The proposed refractory coatings are applicable for metallic and non-metallic structures, with the option of using them to protect machinery components in the chemical industry, metallurgy, and mining. Given that pyrophyllite has a low hardness, the goal was to improve the coating's resistance to cavitation erosion by adding 20 wt.% of hard refractory materials, i.e., crushed and micronized waste bricks based on mullite and corundum, respectively. Previous studies have demonstrated that protective coatings using a pyrophyllite filler have refractory qualities but insufficient resistance to cavitation erosion. As a result, the composition of refractory coatings, the preparation techniques, and the coating manufacturing process were altered. This study presents a simple method for combining conventional coatings made of refractory fillers (primary resource: pyrophyllite) with waste materials (mullite brick and corundum brick) used as reinforcement in protective refractory coatings for metal and non-metal structural elements that are highly resistant to cavitation erosion
Reduced Fast Firing in the Ceramic Tile Manufacturing Process with Inorganic Additives: A Step Up for the Sector.
No full textThe use of European patent-protected inorganic additives to improve the characteristics of
ceramic tiles is covered in this study. Modifications in shrinkage, modulus of rupture, and water
absorption were noted when different kinds of additives consisting of phosphoric acid and
hydrated sodium silicate were applied to the ceramic mass at varying percentages (0.15, 0.30, and
0.50 %) in a laboratory setting. It was anticipated that using both chemicals at once would increase the slurry's viscosity and reduce the firing temperature, resulting in less energy
consumption and less CO2 being released into the atmosphere. After choosing the best
combination and concentration of additives, a number of industrial tests are carried out. In
industrial settings, the features of both regular ceramic mass and mass containing the chosen
additive were determined without modifying process parameters, while producing monoporosa
floor tiles with a water absorption of below 3.0 %. It is seen that the additives in such a small
percentage reduced the fire time to 55 minutes cold-to-cold without compromising the quality of
the final products. By employing lower-quality raw materials, accelerating the process, lowering
the maximum firing temperature, and boosting capacity by 6.8 %, the use of additives in the
manufacturing of ceramic tiles creates new potential to improve the product's mechanical and
physical properties and lower production costs per unit of output. As a result, considerable energy
savings and a reduced carbon footprint are achieved
Osnovni aspekti ocenjivanja i verifikacije stalnosti performansi betona
No full textDonošenjem Pravilnika o tehničkim zahtevima za beton odgovornost za stavljanje / isporuku betona na tržište preuzima proizvođač betona, kome se nameću znatno veće obaveze, nadležnosti i zahtevi koje mora ispuniti.
Očekujemo da Pravilnik doprinese poboljšanju kvaliteta betona i povećanju uređenosti na tržištu ovih građevinskih proizvoda.
Ovim radom predstavljeni su osnovni aspekti ocenjivanja i verifikacije stalnosti performansi betona, u skladu sa Pravilnikom o tehničkim zahtevima za beton. Objašnjene su obaveze proizvođača i imenovanog sertifikacionog tela za fabričku kontrolu proizvodnje
Proračun ugiba grednih struktura na osnovu izmerenih vrednosti dilatacija
Get PDFPonašanje struktura pod delovanjem različitih vrsta opterećenja
određene su njenim deformacionim karakteristikama,
globalnim deformacionim karakteristikama – pomeranjima
i rotacijama i lokalnim deformacionim karakteristikama
- dilatacijama u materijalu strukture. Poznavanjem
globalnih i lokalnih deformacionih karakteristika strukture
ostvarujemo mogućnost da pratimo ponašanje strukture u
celini ili nekog njenog segmenta. Osnovni cilj ovog istraživanja
je provera algoritma proračuna za dobijanje vertikalnih
pomeranja - ugiba strukture, na osnovu poznatih vrednosti
dilatacija u materijalu strukture, pri delovanju opterećenja.
Provera algoritma sprovodi se poređenjem numeričkih i eksperimentalnih rezultata