Repository of the Institute for Material Testing (RIMS)
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Development of recycled cement made from biowaste
No full textMany studies on techniques for diminishing the environmental impact, reducing greenhouse gas emissions, and decreasing industrial and biowaste have been conducted with the mutual goal of achieving sustainable development. The use of industrial byproducts as raw materials for cement clinker production is becoming more common in the Portland cement industry. Eggshell is a biowaste produced in huge quantities by households and the food industry. Eggshell powder has a trigonal-calcite structure and properties similar to limestone; therefore, it can substitute limestone in the cement clinker mix design. In this work, bio-waste cement was produced at temperatures below the standard 1470°C utilizing mechanically activated eggshell powder. Under the same conditions as bio-waste cement, limestone cement clinker was also synthesized. Instrumental tests (X-ray diffraction, scanning electron microscopy, differential scanning calorimetry, and thermogravimetry analysis) were employed to analyze the mineral phases in the produced cements. The results showed that eggshell-cement had four major cement clinker phases (C3S, C2S, C3A, and C4AF) that were identical to those in ordinary commercial Portland cement. As a result, this study demonstrated that it is possible to recycle eggshell waste to partially substitute limestone as a raw material for cement clinker manufacturing
International Journal of Manufacturing Economics and Management
No full texthttps://www.ijmem.ro/editorial-board.ph
Procedure for assessment of the clays suitability towards fast drying
Get PDFDuring the last 10 years it was shown that Deff – MR curve pattern is unique and very useful. This ability was firstly embedded in the procedure for setting up the fast drying regimes several years ago. This incredible pattern was used again in this invited paper. Actually, if the test samples formed from the same clay do not crack during drying in at least two isothermal experiments in which drying air temperature was different, while drying air humidity and velocity were constant, the unique line can be constructed. This line is linking corresponding Deff – MR curves through the same characteristic point. For simplicity reasons it was chosen to construct and use only the unique line pulled through characteristic E points. Its slope was proposed as the objective criteria for evaluation of the clays suitability for the rapid drying application. It was found that clays, for which the unique line slope is larger, had better dimensional and mechanical properties and were more suitable for the construction of the fast drying regimes
Comparison of gamma and X radiation attentuation characteristics for ordinary concrete with barite and concrete with limonite and steel
No full textDuring the implementation of procedures for designing building barriers for protection against gamma and X radiation, the unavoidable question of choosing construction materials with appropriate mechanical and radiation characteristics for protective barriers arises. Based on engineering practice, it is necessary to compare different types of concrete used for the construction of facilities where there are sources of gamma and X radiation, such as in cases where radiation sources appear in medical facilities with linear accelerators, cyclotron installations for accelerating nuclear particles, in the environment of nuclear reactors, in radioactive waste storages, or in radiation sterilization unit s. In the cost-benefit analysis, several criteria are used to evaluate the characteristics of the concrete, so that in addition to the mechanical characteristics, the radiation characteristics of the construction material are also considered. One of the most important characteristics of concrete for radiation protection is its total mass attenuation coefficient. In this paper, computer code XCOM was used for the calculation of the total mass attenuation coefficients in energy range from 0.01MeV to 100 MeV for three types of concrete: ordinary concrete, concrete with barite and concrete with limonite and steel. Based on the comparison of calculation results, it was concluded that concrete with limonite and steel has greater protective power than other two concrete types for the gamma and X radiation energy less than 30 keV. The second important conclusion is that the concrete with barite has greater protective power than other two concrete types in the range of photon energy from 30 keV to 300 keV, and for photon energy greater than 6 MeV. A detailed analysis of the calculation results found that in the energy range of 400 keV to 6 MeV values for the total mass attenuation coefficients are approximately the same for three different types of concrete
Parametric programs for 3D modeling in the function of NDT and determining life of pressure vessels
Get PDFPreparation for non-destructive testing (NDT), preparation of test reports, and control
calculation of a pressure vessel using the finite element method (FEM), with or without identified
irregularities, requires the use of commercial parametric modeling programs. 3D modeling
programs enable the determination of the most critical part of the pressure vessel construction
as well as the modeling of irregularities after the tests that occurred during the construction,
calculation, and exploitation of the pressure vessel construction itself.
Irregularities are reflected in the form of improperly performed welded joints, cracks, corrosion,
erosion or cavitation of materials, and are used for the preparation of test reports and control
calculations of the pressure vessels construction with and/or without identified irregularities and
defects, with the aim of making the correct decision on continued exploitation of the pressure
vessel construction or its degree of repair.
The possibility of an unlimited number of views, as well as the possibility of an unlimited number
of sections of the entire pressure vessel structure or its part, releases us from creating
complicated 2D sketches for the purpose of NDT or control calculation of the pressure vessel
FEM structure.
In connection with other computer programs or for the calculation of FEM (fracture mechanics,
fatigue), pressure vessel models made in 3D, enable the preparation of a quality test report with
the defined traceability and repeatability required by the SRPS ISO/IEC 17025 standard, as well
as the making of the correct decision on the exploitation and service life of the structure pressure
vessel
The lumped approach in drying modeling of roofing tiles – variable effective diffusivity determination
Get PDFIn this paper, the drying modeling of roofing tiles was done using a "lumped" approach. In
other words, several forces that are influencing internal moisture transport are combined to
create effective moisture diffusivity. For this reason, the effective diffusivity coefficient was
added to Cranck's diffusion equation. In their earlier works, the authors published the solution
to the diffusion equation, which assumes that effective diffusivity is constant. It was
demonstrated that, particularly if shrinkage is not taken into account during the computation
stage, the simulated drying curves differ from the experimental results. The next step was to
ascertain the time-dependent effective diffusivity and to more precisely anticipate the drying
kinetic. The general functional relationship between effective moisture diffusivity and Fourier
number was first determined to fulfill this assignment. Experimental proof of the proposed
model was provided. Less than 3% of the outcomes from the simulation and the experiment
deviated from each other. This was a resounding affirmation that effective diffusivity is not
constant during drying and that all internal transport mechanisms are observable in their timedependent
relation
Pečeni presovani pelet kao tehnika pripreme uzorka sirovih glina za hemijsku analizu pomoću energetsko disperzivne rendgensko fluorescentne spektrometrije
No full textKORISNIK TEHNIČKOG REŠENJA: Institut za ispitivanje materijala IMS a.d.iz Beograd
Experimental Determination of the Critical Value of the J-Integral that Refers to the HSLA Steel Welded Joint
No full textFracture mechanics, as a scientific discipline dealing with the study of cracks in welded structures, has defined parameters and introduced new test methods in order to better determine the tendency to crack growth, critical conditions for rapid fracture development, material resistance to rapid crack propagation and better definition of other parameters for assessing the behaviour of the material and the safety of the structure in the presence of cracks. In this paper, the focus is on determination of the parameter of elastic-plastic mechanics of J-integral, more precisely, on examination of the critical value of J-integral (JIc) of the welded joint of HSLA steel. The position of the tip of the fatigue crack and the properties of the region where fracture propagation occurs are main indicators of influence of the heterogeneity of the NN-70 welded structure and mechanical properties. Resistance to cracking in the welded joint shows that the heterogeneity has a major impact on the resistance to crack initiation and propagation, in elastic as well as in the plastic region
Technical solution for the foundation of the elixire group waste to energy treatment in Prahovo
Get PDFThe paper presents the technical solution for the foundation of the facilities of the
Boiler House for the energy utilization of waste and chimneys. Next to the boiler house, the
construction of a Bunker for waste storage is planned, which is founded at a depth of 6.0m below
the top of the boiler house's base plate. Based on the conditions of limited settlement, the
foundation of the boiler house was envisioned on drilled piles, while a hidden pile wall was
designed to protect the foundation pit of the bunker, which has the function of preventing large
deformations of the boiler house structure and does not jeopardize its stability. Calculations of the
bearing capacity of the piles based on the soil parameters from the geotechnical study are
presented, as well as the results of the pile tests with axial vertical pressure force
X-ray fluorescence spectroscopy of eggshells as a potential raw material in the construction industry
Get PDFDue to its chemical composition based on CaCO3 and low price, eggshells, as waste from one of the most widely consumed foods worldwide, are receiving increased attention in building and construction industry studies. The goal of this study was to see if the chemical composition of eggshells could be utilized to distinguish eggs from different production systems. In Serbia, eggs were taken at random from ten commercial cages and ten commercial free-range flocks. Using energy dispersive X-ray fluorescence spectroscopy (EDXRF) and a chemometrics approach, twenty eggshell samples from each flock were tested for element composition (Ca, P, Mg, Na, Al, Cu, Mn, Fe, K, S, and Zn). Analysis showed that free-range eggshells had higher levels of macrominerals (P, Mg, and Na) but lower levels of microminerals (Cu, Fe, K, S, and Mn) than caged eggshells (P<0.05). A large degree of variability within and between production systems was observed for all tested elements. The findings suggest that EDXRF and chemometric analysis of eggshell elemental profiles could provide a useful and effective tool for distinguishing between free-range and caged eggs