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Assessment of construction and demolition waste application for improving frost resistance in masonry clay units
No full textThe main objective of the research was to estimate the feasibility of construction and demolition waste (CDW) application in the production of frost-resistant masonry clay elements. After being formed into hollow masonry blocks and bricks, the experimental samples were dried and fired. Chemical, granulometric, mineralogical, differential-thermal, and thermogravimetric analyses were used for characterizing the materials. Drying sensitivity and plasticity were assessed using the Bigot and Pfefferkorn tests. Linear shrinkage and compressive strength were determined on green and fired ceramic samples. Frost resistance was tested in accordance with EN 772-22 and ASTM C1167-22. The mercury intrusion porosimeter and RapidAir 457 were used in the evaluation of the pore size distribution. Clay elements fired at lower temperatures proved more frost-resistant. Waste-based elements exhibited improved frost resistance compared to standard bricks and hollow blocks. The compressive strength of the waste-added building products was reduced, but it still exceeded the standard strength values for their application in load-bearing walls.IF (2023) 1.4, 16/29 Materials Science, Ceramic
Exploring the Efficiency of Magnetic Separation and Gravity Concentration for Valorizing Pb-Zn Smelter Slag in a Circular Economy Framework
No full textThe presented work offers an innovative process scheme for valorizing Pb-Zn slag, which involves crushing, grinding, and separation techniques to concentrate valuable components (non-ferrous metals). This methodology could have a significant impact on the global beneficiation of metallurgical slags since it is significantly more simple, environmentally friendly, and cost-effective than standard pyro- and hydrometallurgical procedures. According to previous physicochemical and mineralogical studies, Pb-Zn slag is a valuable secondary raw material. This inhomogeneous technogenic resource contains substantial amounts of non-ferrous metals (Pb, Zn, Cu, and Ag). However, laboratory tests have indicated that the Pb-Zn slag contains highly uneven amounts of valuable metals, ranging from several g/ton to tens of g/ton. The main issue is that traditional metallurgical procedures for releasing beneficial elements are not commercially viable since the elements are “trapped” within the amorphous aluminosilicates or intergrowths of alloy grains and glassy phases. Gravity concentration (Wilfley 13 shaking table) and magnetic separation (Davis separator and disk separator) were used to obtain the final concentrate following comminution and grindability testing. The gravity concentration proved more effective. Namely, magnetic separators could not process nor adequately separate beneficial non-ferrous elements because they were merged together with iron-bearing minerals and aluminosilicates in amorphous Pb-Zn slag grains. With the gravity concentration approach, 12.99% of the processed slag belonged to ∆T fraction (concentration of non-ferrous metal alloys), while remaining 87% corresponded to the tailings fraction (∆L). The total amounts of recovered Pb, Zn, Cu, and Ag from ∆T and ∆L fractions were 5.28%, 6.69%, 0.58%, and 76.12 ppm and 1.22%, 6.05%, 0.43%, and 15.26 ppm, respectively. This streamlined approach to valorizing Pb-Zn slag can reduce the need for hazardous chemicals used in hydrometallurgical refinement operations, as well as the extremely high temperatures required for pyrometallurgical processing. This is the first study to investigate the viability of this novel methodology, which involves the direct examinations of the Pb-Zn slag feed with various alternative technologies for separation and concentration. After extracting the valuable metals, the amorphous aluminosilicate part of the Pb-Zn slag can be reapplied as an alternative raw material in the building sector, adding to the circularity of the suggested approach
The application of the thin and lumped appreoach for comparision of the drying kinetic registered for various thin clay slabs
No full textThe main goal of this paper was to compare the lumped and thin layer modelling approach for
describing the drying kinetics of clay slabs extruded from various clays. Four drying regimes
were firstly designed. The drying velocity was fixed to 3 m/s in all experiments. The drying
temperature and humidity were hold at 400C and 60% in the first drying regime. These
parameters were raised for 100C and 10% in each following experiment. Eight thin-layer models,
including the new one, was used. The non-linear regression analysis was applied for fitting the
experimental data. The lumped approach is relatively new and it assumes that different drying
mechanisms which affects the internal moisture transport are combined and presented in a form
of the effective diffusivity constant. The lumped modelling approach has retained and reused the
form of the Crack’s diffusion equation with only one update. The pure diffusion coefficient was
replaced with the effective one. Since the effective moisture diffusivity can vary with time the
most advanced lumped models are taking this into account by defining the relationship between
the effective diffusivity coefficient and the Fourier number. This model was adopted in this paper. Results have shown that the best thin layer model was the new one. It was found that this
model has up to 5 % deviation from the experimentally registered data at the beginning of the
first drying segment. The lumped model was deviating from the experimental data for only 2%.
This was another confirmation that the conjugation degree in thin layer modelling is lower than in
the case of the lumped approach. This means that thin layer model application is actually very
limited, especially for porous materials which predominantly shrinks during drying, due to
theoretical assumptions which simplifies the boundary conditions for which the equations were
originally developed
Effect of the titanium-dioxide addition on the structural, dielectric, and mechanical properties of different cement-based mortars with corundum aggregate
No full textThe primary objective of this study was to look into the role of titanium dioxide in the production of corundum-based mortars, with a focus on finding the optimal mortar composition for achieving improved mechanical and dielectric performances. Changes in the mix design (different binders, different additive dosages), as well as their effects on the hydration pathway, chemical bonds, phase modifications, and microstructure, were examined. These findings were then correlated to the designed mortars' mechanical strengths and dielectric properties. Experimental mortars were produced with binders made from ordinary Portland cement, high alumina cement, and their mixtures, and corundum as aggregate. Titanium dioxide was employed as an additive (3 and 5 wt%). Nine different mortars were submitted for comprehensive mineralogical and microstructural characterization upon curing and solidification. The compressive and flexural strengths were monitored throughout the 28-day period. The dielectric constant (εr), dielectric loss tangent (tan δ), and electrical resistivity (ρ) were measured over a frequency range of 100 Hz to 1 MHz. XRD analysis highlighted the appearance of mayenite as a dielectric-prone phase in the samples doped with titanium dioxide. Differential thermal analysis and FTIR spectroscopy identified a higher amount of extra-low crystalline phase in OPC and HAC mortars with TiO2 addition, which accelerated hydration mechanisms, created a surplus of hydration products and made a more compact cement matrix. TiO2 added in 3 wt% amount led to higher mechanical strengths in OPC-based mortars, while it improved the dielectric properties of HAC mortars
Istorijski malteri : od karakterizacije do konzervacije
Get PDFPublikacija Istorijski malteri – od karakterizacije do konzervacije predstavlja jedan od rezultata projekta Mortar Design for Conservation – Danube Roman Frontier 2000 Years After (MoDeCo2000), koji je finansirao Fond za nauku Republike Srbije od 2020. do 2022. godine kroz program PROMIS. Projekat je sproveden u saradnji Arheološkog instituta, Tehnološkog fakulteta Novi Sad Univerziteta u Novom Sadu i Instituta za ispitivanje materijala. Tema projekta su krečni malteri građevina podignutih u periodu od I do VI veka na delu dunavskog limesa koji se nalazio na teritoriji današnje Republike Srbije. U Srbiji se nalaze ostaci brojnih građevina iz svih istorijskih perioda, ali malteri ugrađeni u njihove strukture do sada nisu bili predmet sistematskog proučavanja. Period čiji je razvoj graditeljstva najdirektnije bio uslovljen razvojem pripreme i primene krečnog maltera predstavlja vreme rimske dominacije. Kroz projekat MoDeCo2000 sprovedeno je istraživanje graditeljstva nastalog tokom ovog perioda na teritoriji dunavskog limesa – granice Rimskog carstva na reci Dunav. S obzirom na to da su rimski krečni malteri u svetu decenijama predmet brojnih naučnih projekata, MoDeCo2000 predstavlja važan doprinos naučne zajednice Republike Srbije razvoju ovih istraživanja, ne samo kroz osvetljavanje dela slike graditeljskog, pa i društveno-ekonomskog razvoja prostora centralnog Balkana u periodu od I do VI veka nove ere, već i tradicionalnog graditeljstva na predmetnoj teritoriji uopšte. Osim istraživačkog cilja projekta, kao jednako važan je bio onaj usmeren na praktičnu arhitektonsku konzervaciju, odnosno direktnu primenu naučnih rezultata projekta u procesima očuvanja istorijskih građevina u Srbiji, u skladu sa međunarodnim dokumentima iz oblasti zaštite kulturnog nasleđa
Landscape and its Traces in Roman Mortars of the Danube Limes in Serbia
No full textThe research within the project Mortar Design for Conservation - Roman Danube Frontier 2000 Years After (MoDeCo2000), dealing with Roman buildings in Serbia situated along the former Danube Limes was carried out using data from archaeological, architectural, and geological contexts, combined with mineralogical, chemical and material science research. The aim of the research is to reveal unknown data on ancient provincial construction, but also to contribute to future conservation processes, offering a database of historic mortars and raw materials used at the mentioned territory during the centuries. The research has confirmed the well-known unwritten rule of using local materials in historical constructions. The unique landscape around the Viminacium Archaeological Park with the remains of structures dating to ancient, Early Byzantine, and medieval periods, is an area where four archaeological sites, with nine buildings and forty-two different mortars, were examined, making it an ideal case study for this paper
Zgornjekredni turbiditi južnega obrobja Beograda: Podrobna opredelitev začetka santonijske konvergence, dokazi iz Savske šivne cone (Guberevac-Babe, severna Šumadija, Srbija)
No full textAs ancient depositional systems associated with active continental margins, turbidites may provide crucial information on orogenic evolution. This paper offers new stratigraphic and structural data on one of the late Alpine turbidite systems of the Late Cretaceous age (Guberevac-Babe-Ropočevo area; Serbia). The two opposite yet juxtaposed tectonic systems were initially deposited within the Sava Suture Zone and East Vardar Zone, whereby the former experienced Upper Cretaceous contractional- and extensional-type deformations. The new biostratigraphic dating constrains the age of mapped compressional structures, which indicates their Santonian age. This deformed segment of the newly dated Santonian clastic-carbonate turbidite sequence near the Guberevac site exposes new important compressional structures. The folds, reverse faults, and tectonic stylolites are allocated several kilometers from the primary deformation (Bela Reka thrust fault), positioned within the crustal footwall of the overriding East Vardar Zone.
The complexity of the geological processes in the Guberevac-Babe-Ropočevo area is further revealed by the previously mapped layering of Upper Cretaceous strata, exposed within the wider investigated area. Our combined field study provides a new statistical analysis of structural elements such as faults, folds, and bedding planes, adding to the depth of the understanding of the Sava Suture Zone. The observed contractional structures, mesoscopic folds, thrust faults, two-generation cleavage planes, as well as the produced statistical structures, are mostly imprinted into the out-of-deformation front or within the mixed clastic-carbonate turbidites of the Sava Suture Zone (Guberevac-Babe area). The composite study shows that the investigated footwall segment, represented by the deformed Sava Suture Zone turbidites, underwent tectonic shortening during Santonian (convergence onset). After the main crustal thickening event ceased, the Guberevac-Babe-Ropočevo suture segment was reactivated several times (post-orogenic extension). The investigated segment of the Neotethyan Vardar paleosuture experienced a total of four deformation stages spanning Late Cretaceous to Miocene times. These include the Late Oligocene reactivation and emplacement of the Glavčina-Parlozi Late Oligocene subvolcanic body and the slightly younger Stenička bara Miocene igneous system.Turbiditi, kot sedimentacijski sistemi, vezani na aktivne robove celin, so turbiditi nosilci pomembnih podatkov o orogenem razvoju območja. V tem članku so predstavljeni novi stratigrafski in strukturni podatki o enem od alpskih turbiditnih sistemov iz časa pozne krede (območje Guberevac-Babe-Ropočevo; Srbija). Znotraj Savske šivne cone in Vzhodne Vardarske cone sta bili odloženi dve sinorogeni zaporedji, pri čemer je bilo prvo podvrženo poznokrednim kompresijskim in ekstenzijskim deformacijam. Glede na nove biostratigrafske podatke je do nastanka kompresijskih struktur prišlo v santoniju. V deformiranem delu santonijskega klastično-karbonatnega turbiditnega zaporedja v bližini Guberevaca so vidne nove pomembne kompresijske strukture. Gube, reverzni prelomi in tektonski stiloliti so vidni nekaj kilometrov stran od primarne deformacije (nariv Bela Reka), v talnini narinjene Vzhodne Vardarske cone. O kompleksnosti geoloških procesov na območju Guberevac-Babe-Ropočevo pričajo tudi plasti zgornjekrednih kamnin, ki so bile predhodno kartirane na širšem območju. V sklopu naše terenske študije smo izvedli statistično analizo strukturnih elementov, kot so prelomi, gube in plasti, kar prispeva k boljšemu razumevanju Savske šivne cone. Opazovane kompresijske strukture, kot so mezoskopske gube, narivi in klivažne ravnine dveh generacij, kot tudi pridobljeni statistični podatki o strukturah, se večinoma pojavljajo v prednarivnem čelu ali znotraj mešanih klastično-karbonatnih turbiditov Savske šivne cone (območje Guberevac-Babe). Celotna študija kaže, da je bil preiskovani segment talnine, ki ga predstavljajo deformirani turbiditi Savske šivne cone, izpostavljen tektonskemu krčenju v santoniju (začetek konvergence). Po koncu glavnega dogodka debeljenja skorje je bil šivni segment Guberevac-Babe-Ropočevo večkrat reaktiviran (postorogena ekstenzija). Preučevani segment neotetidine vardarske paleosuture je med pozno kredo in miocenom skupaj doživel štiri faze deformacij. Te vključujejo pozno-oligocensko reaktivacijo ter umestitev pozno-oligocenskega subvulkanskega telesa Glavčina-Parlozi in nekoliko mlajšega, miocenskega magmatskega sistema Stenička bara
Advanced Chemical Analysis of Fly Ash Leachate and Mortars Using ICP-OES
No full textThis study introduces a new approach using inductively coupled plasma optical emission spectrometry (ICP-OES) for the analysis of the chemical composition (34 elements: Al, Be, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, V, Zn, Pb, Bi, Si, Zr, As, Hg, Se, Sb, Sn, Ti, Ba, B, Ag, Mg, Ca, K, Na, S, P, Li) of fly ash leachate, as well as mortars containing fly ash, zeolite, and bentonite. The method underwent rigorous validation and addressed measurement uncertainties. It offers an efficient way to detect traces of undesirable elements in fly ash leachate and in construction materials containing fly ash, zeolite, and bentonite, such as cement binders and mortars. Laboratory testing of cement binders and mortars verified the accuracy and precision of the method, comparing results with standard limits. Multivariate analyses, including cluster and principal component analyses, were used to understand sample relationships and verification the developed ICP-OES method.http://www.serbianceramicsociety.r
The characterization of changes in ground penetrating radar signal due to chloride induced corrosion of reinforcement in concrete
No full textCorrosion of reinforcement in concrete, associated with consequent cracking, delamination, and
spalling, is the greatest threat to the durability of reinforced concrete (RC). Timely detection of
corrosion could be achieved using non-destructive testing (NDT) methods, which in turn could
minimise, prolong, or avoid the serious consequences of corrosion. Ground penetrating radar
(GPR) is proving to be one of the most beneficial NDT methods, especially due to its efficiency
and versatility. Research activities in this field have increased, but uncertainties remain
regarding the response of GPR in corrosive environments. In particular, the extent and even the
sign of the amplitude change due to corrosion products is unresolved. This work addresses the
observation and characterisation of GPR signal changes due to chloride-induced corrosion
performed in the laboratory and with numerical simulations. It is expected that the findings of
this work will contribute to a more accurate and detailed corrosion assessment procedure for
RC structures