Faculty of Mining, Geology and Petroleum Engineering Repository
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The experimental assessment of underground hydrogen storage : master's thesis
No full textUporaba vodika moguće je rješenje za uravnoteženje fluktuacija u količini energije dobivene obnovljivim izvorima. Najboljim načinom skladištenja vodika smatra se utiskivanje u pogodne podzemne strukture. Rad prikazuje ispitivanja na uzorcima stijena za dvije bušotine u sjevernoj Italiji, s ciljem utvrđivanja mehanizma njihovih reakcija s vodikom, metanom i njihovom smjesom, pod povišenim tlakom. Nad uzorcima je provedena mineraloška analiza te mjerenja mase, propusnosti i ultrazvučna mjerenja brzine p-vala. Mjerenja nisu pokazala značajnu promjenu koja bi ukazivala na kemijske reakcije plina i minerala u stijeni.Hydrogen utilisation provides a potential solution for load balancing of energy production and energy storage. Subsurface storage of hydrogen has been regarded as an optimal solution for such purposes. This thesis presents the methodology of a series of experiments conducted on rock samples in order to assess possible rock-gas interactions in high-pressure conditions, including mineralogical analysis, weight monitoring, permeability and ultrasonic measurements. The thesis results indicate no existence of geochemical reactions
Stakeholder engagement in the radioactive waste management program : master's thesis
No full textU ovom diplomskom radu dan je kratki pregled gospodarenja radioaktivnim otpadom, s naglaskom na uključivanje dionika u program gospodarenja radioaktivnim otpadom. Dionik je svatko na koga utječe određena aktivnost. Program uključivanja dionika u program gospodarenja radioaktivnim otpadom bitno se razlikuje od države do države. Nemoguće je napraviti jedinstven standardiziran program zbog zakonskih, kulturoloških i demografskih razlika država. U radu je prikazan pregled vijesti i informacija koje Fond za financiranje razgradnje i zbrinjavanja radioaktivnog otpada i istrošenoga nuklearnog goriva Nuklearne elektrane Krško u Hrvatskoj prenosi dionicima. Također je napravljena analiza članaka na najposjećenijim hrvatskim internetskim portalima u kojima se spominje radioaktivni otpad u Hrvatskoj.This master's thesis provides a brief overview of radioactive waste management, with an emphasis on the stakeholder engagement in the radioactive waste management program. A stakeholder is anyone who is affected by a certain activity. Stakeholder engagement in the radioactive waste management program is different in every country. It is not possible to create a unique standardized program due to the legal, cultural and demographic differences between countries. An overview of the news and information that the Fund for financing the decommissioning of the Krško Nuclear Power Plant and the disposal of Krško NPP radioactive waste and spent nuclear fuel conveys to stakeholders was made. Also, an analysis of articles on the most visited Croatian internet portals that mention radioactive waste in Croatia was made
Utjecaj dubine rezanja reznih pločica lančane sjekačice na količinu odlomljenog materijala : završni rad
No full textGlavni cilj ovog završnog rada je potvrditi prethodno postavljenu hipotezu u kojoj je pretpostavljeno da s povećanjem dubine rezanja alata lančane sjekačice dolazi do povećanja mase odlomljenog materijala i veličine odlomljenih čestica . U tu svrhu su provedena laboratorijska ispitivanja na uređaju za pravolinijsko rezanje stijena koja omogućuje simulacija rada reznog organa lančane sjekačice u realnim uvjetima. Laboratorijska ispitivanja provedena su u dva slučaja i to u ukliještenim te ne ukliještenim uvjetima u Laboratoriju za rudarsku mehanizaciju i arhitektonsko-građevni kamen na Rudarsko-geološko-naftnom fakultetu Sveučilišta u Zagrebu
TBM modeli predviđanja napredovanja. Usporedba napredovanja predviđenog u natječaju i u stvarnosti. Projekt: Anneberg–Skanstull tunel (Stockholm, Švedska) : diplomski rad
No full textThe most widely used prediction model for hard rock is the Colorado School of Mines (CSM) model, which was used for tender prediction in the Anneberg - Skanstull Tunnel (AST) project. However, during the construction phase, the TBM penetration rate was lower than predicted in the model. Intact rock strength is usually the first rock mechanic parameter obtained from geological investigation for tunnelling projects. This is one of the key parameters used in the Tunnel Boring Machine (TBM) prediction model. The most common rock mechanic test for intact rock strength determination is the Uniaxial Compressive Strength (UCS). After core sampling from the tunnel, new UCS values were obtained, analysed, filtered, and implemented in the CSM model to generate new penetration rates for different lithologies.Za stijene visoke čvrstoće, najčešće korišteni TBM model predviđanja je Colorado School of Mines (CSM), koji je i korišten u natječaju za izradu Anneberg-Skanstull tunela (AST). Međutim, tijekom konstrukcije tunela, uočeno je sporije napredovanje nego što je predviđeno u modelu. Svojstva stijena obično su prva informacija dobivena iz geoloških istraživanja kod izrade tunela. Ovo je jedan od ključnih parametara korištenih kod izrade modela za predviđanje napredovanja stroja za bušenje tunela (eng. TBM). Najčešća metoda ispitivanja stijenske mase je Jednoosna Tlačna Čvrstoća (eng. UCS). Nakon jezgrovanja u tunelu, nove UCS vrijednosti su dobivene, analizirane i uvrštene u CSM model s ciljem generiranja novih stopa napredovanja za druge litologije
Ugljični otisak rudarskih zahvata eksploatacije arhitektonsko-građevnog kamena u Hrvatskoj u prvih 10 godina članstva u Europskoj uniji: analiza studija utjecaja zahvata na okoliš : završni rad
No full textOvaj rad analizira ugljični otisak odnosno emisije stakleničkih plinova novih zahvata eksploatacije arhitektonsko-građevnog kamena u Hrvatskoj tijekom prvih deset godina članstva u Europskoj uniji. Rastuće emisije stakleničkih plinova predstavljaju ozbiljan izazov za klimu i ljudski okoliš na Zemlji. Europska unija postavila je ambiciozan cilj smanjenja emisija stakleničkih plinova, a Republika Hrvatska nastoji pridonijeti tim ciljevima. Rudarska industrija doprinosi globalnim emisijama ugljičnog dioksida, ali je također i ključna za smanjenje globalnih emisija ugljika u širem gospodarstvu. Za potrebe analize prikupljeni su podaci o zahvatima eksploatacije arhitektonsko-građevnog kamena u Republici Hrvatskoj nakon stupanja u Europsku Uniju i primjene propisa usklađenih sa propisima Unije. Primjenom odgovarajuće metodologije izračuna, korištenjem odgovarajućih faktora konverzije izračunat je ugljični otisak odnosno ukupne emisije stakleničkih plinova (izražene kao ekvivalent ugljičnog dioksida). U procesu prikupljanja podataka utvrđeno je kako su u razdoblju od 2013. do 2023. godine, izrađene 23 studije utjecaja eksploatacije arhitektonsko-građevnog kamena, no prije 2016. godine studije nisu bile trajno javno dostupne te su podaci u ovom radu prikupljeni iz 17 studija koje jesu bile javno dostupne. Rezultati su pokazali kako godišnja vrijednost potrošnje dizelskog goriva svih novih zahvata iznosi prosječno 533 kt/god (prosječno 167 kt/godišnje po zahvatu), a ugljični otisak novih zahvata iznose u prosjeku 2,6 kt CO2 ekv /god (prosječno 1 kt kt CO2 ekv /god po zahvatu). Specifična potrošnja dizelskog goriva po zahvatu iznosi prosječno 23,68 kg CO2 ekv /m3 mineralne sirovine u sraslom stanju, a ugljični otisak prosječno 86 kg CO2 ekv /m3 . Usporedba ugljičnog otiska novih zahvata eksploatacije arhitektonsko-građevnog kamena sa emisijom stakleničkih plinova u Republici Hrvatskoj pokazala je kako novi zahvati imaju manje od 0,009% udjela u godišnjoj emisiji stakleničkih plinova u RH te je zaključeno kako nemaju značajne negativne utjecaje na klimatske promjene. Preporuka za buduća istraživanja je proračunati kumulativni ugljični otisak eksploatacije i razmatrati tehnološke i metodološke pristupe kojima bi se tijekom i nakon eksploatacije arhitektonsko-građevnog kamena u Hrvatskoj mogao dati mali doprinos smanjenju emisija stakleničkih plinova u RH
The possibility of torque reduction in drilling of horizontal wells placing protection ring on the drill pipes joint : doctoral dissertation
No full textTijekom izrade horizontalne bušotine mogu se pojaviti različiti tehnološki problemi, a najčešće su oni posljedica povećanih vrijednosti momenta torzije i sile natega. Kontakt između niz bušaćih alatki i zaštitnih cijevi/stijenki kanala bušotine uzrokuje povećanje sile trenja, što rezultira povećanom silom natega i momentom torzije tijekom izrade kanala bušotine osobito tijekom izrade zakrivljenih i horizontalnih dionica kanala bušotina. Osim spomenutog trenja također dolazi i do intenzivnog trošenja spojnica bušaćih šipki, s obzirom da je spojnica najširi dio niza bušaćih alatki pa samim tim i u neprestanom kontaktu sa stijenkama kanala bušotine. Najbolji je način za smanjenje momenta torzije i sile natega tijekom bušenja korištenje isplaka na bazi ulja ili sintetičkih isplaka umjesto isplake na bazi vode. Međutim, smanjenje momenta torzije i sile natega može se efikasno postići i na način da se u isplaku na bazi vode, koja je ekološki prihvatljivija dodaju komercijalni podmazivači koji imaju zadatak smanjenje koeficijenta trenja. Budući da se tijekom izrade horizontalnih bušotina velikog dosega najveći dio bušenja odvija kroz ležište, za ovo ispitivanje odabrana je polimerna isplaka (engl. drill-in fluid) odnosno fluid na bazi vode posebno namijenjen za bušenje kroz ležišta. Jedno od mogućih rješenja ovog problema je upotreba zaštitnih kliznih prstenova koji bi bili postavljeni na spojnicu bušaćih šipki u kombinaciji sa aditivima (podmazivačima) u polimernoj isplaci u cilju smanjenja momenta torzije i sile natega. Stoga su za ova istraživanja odabrana tri materijala odnosno poliamid 6 (PA6), politetrafluoretilen (PTFE – u nastavku teksta - Teflon) i polioksimetilen (POM), koji bi se potencijalno mogla koristili kao materijali za izradu zaštitnih kliznih prstenova i koji bi se postavili na spojnicu bušaćih šipki. Također, tijekom ispitivanja korištena su tri komercijalna podmazivača Z, X i Y od dva različita proizvođača, kako bi se ocijenio kumulativni utjecaj podmazivača i zaštitnih kliznih prstenova na smanjenje momenta torzije i sile natega tijekom bušenja. U okviru ovog doktorskog rada laboratorijska ispitivanja su provedena u dvije faze. Prva je faza ispitivanja provedena u Laboratoriju za bušotinske fluide na Rudarsko-geološko-naftnom fakultetu, Sveučilišta u Zagrebu gdje su ispitana osnovna fizikalna svojstva polimerne isplake te je provedeno ispitivanje na uređaju za određivanje podmazivosti isplake. Prva faza ispitivanja podijeljena je na tri dijela gdje su u prvom dijelu ispitana svojstva polimerne isplake u koju je dodan podmazivač Z, u drugom dijelu korišten je podmazivač X, dok je u trećem dijelu provedeno ispitivanje na polimernoj isplaci s podmazivačem Y. Na temelju dobivenih rezultata o podmazivosti polimerne isplake u koju je dodan jedan od tri podmazivača Z, X i Y II u različitim koncentracijama odlučeno je koristiti teflon za nastavak ispitivanja u drugoj fazi s obzirom da su kod njega izmjerene najmanje vrijednosti sile trenja. U drugoj fazi ispitivanja ispitano je trošenje ispitnog bloka izrađenog od teflona na uređaju za mjerenje trošenje strojnih elemenata koji su u kontaktu (Timken) na Fakultetu strojarstva i brodogradnje, Sveučilišta u Zagrebu. Ispitano je trošenje ispitnog bloka izrađenog od teflona u polimernoj isplaci sa i bez oteživača u koju je dodan jedan od tri podmazivača u koncentraciji 2% i 4%, pri sobnoj i povišenoj temperaturi. Nakon analiziranja svih podataka dobivenih na uređaju za mjerenje trošenja strojnih elemenata koji su u neposrednom kontaktu može se zaključiti da je trošenje ispitnog bloka izrađenog od teflona minimalno, odnosno u rasponu od 0,08 do 2,79%, te uglavnom posljedica konstrukcije samog laboratorijskog uređaja na kojem je provedeno laboratorijsko istraživanje kao i postupka ispitivanja. Temeljem provedenih sveobuhvatnih laboratorijskih ispitivanja ostvarena su oba postavljena cilja te su potvrđene postavljene hipoteze, odnosno postavljene dobre osnove za daljnja ispitivanja koja bi trebala voditi ka komercijalizaciji ovog tehničkog rješenja za konkretni problem iz prakse.During the drilling of a horizontal well, various technological problems may occur, and most often they are the result of increased values of torsion moment and drag force. The contact between the drill string and the casing/wellbore causes an increase in the frictional force, which results in an increased drag force and torsional moment while drilling the borehole especially during the drilling of curved and horizontal sections of the borehole. In addition to the mentioned friction, there is also wear and tear of the tool joint of drill pipe, considering that the tool joint is the widest part of a drill string and therefore in constant contact with the borehole of the well. The best way to reduce torsional moment and drag force during drilling is to use oil-based or synthetic muds instead of water-based muds. However, the reduction of the torsional moment and drag force can also be effectively achieved by adding commercial lubricants to the water-based mud, which have the task of reducing the friction coefficient. Since during the drilling of extended reach wells, most of the drilling takes place through the reservoir section, a polymer mud was chosen for this test. One of the possible solutions to this problem is the use of protective sliding rings that would be placed on the tool joint of the drill pipe in combination with additives (lubricants) in the polymer mud to reduce the torsional moment and drag force. Therefore, three materials were selected such as polyamide 6 (PA6), polytetrafluorethylene (PTFE – in the following text - Teflon) and polyoxymethylene (POM), from which it was intended to create a protective sliding ring that would be placed on the drill joint of a drill pipe. Also, three commercial lubricants Z, X and Y from two different manufacturers were used, which have the role of reducing the friction factor and thus the torsional moment and drag force. As part of this doctoral thesis, laboratory tests were carried out in two phases. The first phase of testing was carried out in the Laboratory for Drilling Fluids at the Faculty of Mining, Geology and Petroleum Engineering, University of Zagreb, where the basic physical properties of the polymer mud were tested, and a test was carried out on a device for determining the lubricity of the mud. The first phase is divided into 3 parts where in the first part the properties of the polymer mud to which lubricant Z has been added are tested, in the second part lubricant X, while in the third part lubricant Y is tested. In the first part basic physical properties testing was conducted on polymer mud with weighing agents in which lubricant Z was added in different concentrations from 1% to 6% and the lubricity of the mud using metal block and blocks made from Teflon, PA6 and POM. After analysing the data, it was concluded that increasing the concentration of lubricants to 5% and 6% it did not provide additional decrease IV in friction force, so it was decided to continue with concentrations from 1 to 4%. By this conclusion, same tests were conducted using polymer mud without weighing agents in which lubricant Z was added in different concentrations from 1% to 4%. From the obtained data, it has been decided for the second and third part of testing to use polymer mud with and without weighing agents in which lubricant X or Y was added in a concentration of 0,5% as a minimum value, 2% as a mean value and 4% as a maximum value. In the second and third part of testing same tests were conducted as in the first part. In the second part polymer mud with and without weighing agents in which lubricant X was added in concentrations of 0,5%, 2% and 4%. In the third part of first phase polymer mud with and without weighing agents in which lubricant Y was added in concentrations of 0,5%, 2% and 4%. After analysing all the obtained data on the friction force and mud lubricity, it was observed that the value of the friction force created by using test blocks made of Teflon is the lowest compared to all other test materials such as metal, POM and PA6. Based on this, it was decided to continue the laboratory tests in second phase using test blocks made of Teflon and polymer mud with and without weighing agents in which one of three lubricants Z, X and Y was added in concentrations of 2% and 4%. Second phase of testing is divided in two parts, and it was conducted at the Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, on a machine that measures mechanical wear of mechanical elements that are in direct contact (Timken) and provide the value of friction factor. The first part was testing mechanical wear of blocks made from Teflon in a polymer mud without weighing agents in which one of three lubricants Z, X and Y was added in concentration of 2% and 4%. To simulate real parameters, the test was conducted at room temperature and at higher temperature (50 °C). The second part was testing mechanical wear of blocks made from Teflon in a polymer mud with weighing agents in which one of three lubricants Z, X and Y was added in concentration of 2% and 4%. After completing all the tests as part of this doctoral thesis, it can be concluded that the use of a test block made of Teflon significantly reduces the friction factor compared to a metal block. Also, after analysing all the data obtained on the device for measuring the mechanical wear of mechanical elements that are in direct contact, it can be concluded that the mechanical wear of the test block made of Teflon is minimal (0.08-2.79%) and considering the imagined idea of placing sliding protective rings on the tool joint of drill pipe should reduce their mechanical wear, i.e. in this specific case, the protective sliding ring will wear out and not the tool join of the drill pipe
Development of a numerical model of water flow through the unsaturated zone of the Zagreb aquifer in the area of Velika Gorica wellfield : doctoral thesis
No full textOdrživo korištenje i upravljanje zagrebačkog vodonosnika kao strateškog resursa Republike Hrvatske, između ostalog, zahtijeva i identifikaciju i kvantifikaciju svih izvora njegovog prihranjivanja. U cilju kvantifikacije prihranjivanja vodonosnika iz oborine, kao jednog od izvora prihranjivanja, izrađeno je nekoliko je numeričkih dvodimenzionalnih modela tečenja vode i trasiranja čestica kroz nesaturiranu zonu zagrebačkog vodonosnika na području vodocrpilišta Velika Gorica. Pri definiranju geometrije, parametara, početnih i rubnih uvjeta, te za kalibraciju modela korišteni su podaci prikupljeni na istraživačkom poligonu koji se nalazi u prvoj zoni sanitarne zaštite zdenca B-1 vodocrpilišta. Na poligonu se kontinuirano mjere parametri nesaturirane zone pomoću TDR (engl. Time Domain Reflectometry) sondi te meteorološki uvjeti, a izvedena su i geofizička istraživanja te nekoliko eksperimenata trasiranja. Rezultati prognoznog modela za razdoblje od 8. 11. 2019. do 8. 5. 2023. utvrdili su količinu prihranjivanja vodonosnika iz oborine od 16 % i brzinu procjeđivanja oborine od tri godine i tri mjeseca, od trenutka infiltracije na površini terena do razine podzemne vode. Prognoznim modelom za buduće razdoblje (2019. - 2040.) predviđena je dvostruko veća količina procjeđivanja od 36 % što je u skladu s povećanjem učestalosti oborine u razdoblju do 2040. godine. Veća učestalost oborine uzrokovala je i kraće vrijeme procjeđivanja oborine, odnosno godinu dana i četiri mjeseca. Modelima tečenja, kontinuiranim mjerenjima parametara nesaturirane zone na istraživačkom poligonu i eksperimentima trasiranja utvrđeni su faktori koji utječu na količine i brzine procjeđivanja vode u nesaturiranoj zoni: učestalost, količina i intenzitet oborine, sadržaji vode u nesaturiranoj zoni neposredno prije oborinskog događaja, zatim heterogenost naslaga te pojava preferencijalnog tečenja. Pouzdano definiranje rubnog uvjeta infiltracije vode iz oborine do podzemne vode omogućava unaprjeđenje regionalnih numeričkih modela tečenja podzemne vode, a model tečenja vode kroz nesaturiranu zonu temelj je za buduće modele pronosa onečišćenja s površine do podzemne vode.Sustainable management of the Zagreb aquifer, as a strategic resource of the Republic of Croatia, requires identifying and quantifying all sources of its recharge. In order to identify and quantify the recharge from precipitation, as one of the sources of recharge, a numerical two-dimensional model of water flow through the unsaturated zone was built in the area of the Velika Gorica wellfield. A research polygon, consisting of a meteorological station and a shaft, has been established at the Velika Gorica wellfield, where the parameters of the unsaturated zone are continuously measured at different depths using TDR (Time Domain Reflectometry) probes. Geophysical measurements were performed on the surface next to the shaft itself, and the method was electrical resistivity tomography. The measurements performed at the research polygon were used to define the unsaturated flow model geometry, parameters, initial and boundary conditions, and also for model calibration. The results of the flow model for the period from 11/8/2019 to 5/8/2023 pointed out that the precipitation contributes to aquifer recharge by 16 % amount in average. However, that amount varies greatly from year to year. For example, in the one-year periods from 11/8/2019 to 11/8/2020 and from 11/8/2020 to 11/8/2021, the aquifer recharge from precipitation amounts 20 and 19 %, while in the period from 11/8/2021 to 11/8/2022, that percentage is only 2%. The small amount of aquifer recharge from precipitation in 2022 is the result of relatively longer previous dry periods. In 2020, 17% less precipitation occurred than the multi-year average, in 2021 26% less, and in 2022 even 30% less. On top of that, 2022 was an above-average dry year. The most significant amounts aquifer recharge from precipitation occurs at the end and beginning of the year, that is, from December to April, depending on the hydrological year. The periods of significant aquifer recharge from precipitation coincide with the periods of high groundwater levels, high water contents in the unsaturated zone and low values of evapotranspiration. The results of the particle tracking model for the period from 11/8/2019 to 5/8/2023 showed a relatively long travel time of precipitation from the infiltration moment on the ground surface to the moment it reaches the groundwater, i.e., 3 years and 3 months. The factor that most affects the rather slow percolation of precipitation is dry hydrological conditions, that is, below-average amounts of precipitation and their unfavorable distribution (a small number of hours with precipitation). Other factors that affect precipitation percolation and cannot be ignored considering the research location are the heterogeneity of the observed unsaturated zone profile the appearance of preferential flow. The water flow forecast model for the future period (2019 – 2040) predicts a 36 % as the amount of aquifers recharge from precipitation, which is twice as much as the amount simulated by the model for the period from 11/8/2019 to 5/8/2023, which is in accordance with the predicted increase of the precipitation frequency in the future climate. Accordingly, particle tracking model simulated a much shorter travel time of precipitation through the unsaturated zone, i.e. 1 year and 4 months. Unsaturated flow models, continuous measurements of parameters of the unsaturated zone, as well as tracer experiments, showed that the amount of aquifer recharge from precipitation and the travel time of precipitation in the unsaturated zone from the ground surface to the groundwater is affected by the frequency, amount and intensity of precipitation, the water contents in the unsaturated zone before the precipitation event, then the heterogeneity of the observed unsaturated deposit and the appearance of preferential flow. Knowledge of the amounts and rates of precipitation and also of the percolation precipitation process through the unsaturated zone enables the quantification of aquifer recharge from precipitation, which further enables the improvement of regional groundwater flow models, by reliable definition of the boundary condition represented by aquifer recharge from precipitation. Additionally, the unsaturated flow model represents the basis for future models of contaminant transport through the unsaturated zone
Društvena dozvola za rudarenje : završni rad
No full textOvaj rad fokusira se na analizu koncepta društvene dozvole za rudarenje, NIMBY efekta te drugih sličnih fenomena koji predstavljaju značajne izazove u rudarskoj industriji. Istražuje kako rudarska djelatnost utječe na društvo, okoliš i ekonomiju, te analizira međusobne interakcije tih fenomena kroz proučavanje konkretnih slučajeva. Posebna pažnja posvećena je identifikaciji čimbenika koji uzrokuju NIMBY efekt, njihovom utjecaju na lokalne zajednice i poduzeća, te teorijskim pristupima za prevladavanje otpora. Također, rad prikazuje evoluciju NIMBY efekta kroz povijest, njegovu ulogu u kontekstu otvaranja površinskog kopa tehničko-građevnog kamena te recentne primjere otpora rudarskoj industriji u Republici Hrvatskoj
Izrada 3D modela usadnika : završni rad
No full textBušenje je jedna od temeljnih radnji koje se izvode u rudarstvu prilikom izvođenja većine radova. Cilj ovoga rada bio je objasnit temeljne metode bušenja te strojeve koji se koriste prilikom rada. Posebno je naglašena udarno-rotacijska metoda i vanjski čekić jer se rad temeljio na izradi 3D modela usadnika koji je dio vanjskog čekića. 3D model usadnika modeliran je u programu ''AutoCad'' te je isprintan na 3D printeru. Model usadnika segment je vanjskog čekića koji će služiti u nastavi
Resistance to salt crystallization of thin-bedded or platy limestone from the town of Benkovac in Croatia
No full textPurpose. This paper aims to show the petrographic microstructural properties of natural stone as a building material from Benkovac, which is exposed to the influence of sea salt crystallization on the Croatian Adriatic coast.
Methods. The research is based on the graphical and statistical analysis of the results of polarization and electron microscopy, resistance to salt crystallization, ultrasound propagation velocity and uniaxial compressive strength testing. Three diffe-rent lithotypes of limestone – grainy, micritic and laminated are analyzed to evaluate their important petrographic properties that have impact on the durability when material is exposed to the salt crystallization.
Findings. In the petrographic analysis, different characteristics are highlighted, especially those relevant to anisotropy of the structural features as lamination or layering. Besides determination of resistance to the salt crystallization, propagation of ultrasound direct P waves and uniaxial compressive strength are also tested. It is of scientific importance that a change in the internal structure of all samples, especially the laminated lithotype, is observed during the testing. The decrease of ultrasonic propagation velocity, decrease in compressive strength, and durability due to the action of crystallization pressure is a result of increase of the pore space and the fracturing along natural discontinuities such as lamination and layering.
Originality. This paper is the first to deal with the resistance to salt crystallization of the Benkovac stone, especially from the point of view of its petrographic properties. It also deals with the new aspect of interpreting the durability results by combining different methods of evaluating properties that are related to each other.
Practical implications. The knowledge gained in a specific area of the thin-bedded limestone of Benkovac can also be utilized in other places for better and effective protection and preservation of buildings, for which the same type of stone is quarried and used in construction