Uporabnost kamnin iz Liburnijske formacije za proizvodnjo agregata za betone : magistrsko delo

Sevšek, Janez (author), Gale, Luka (mentor), Mladenovič, Ana (comentor), Rogan Šmuc, Nastja (member of the commission for defense), Vrabec, Mirijam (member of the commission for defense)

Izkopne materiale na trasi drugega tira železniške proge med Divačo in Koprom predstavljajo kamnine zgornjekredne–paleogenske flišne formacije, alveolinsko-numulitni apnenec, apnenec Liburnijske formacije in apnenec Trsteljske formacije. Apnenci so se v okviru projekta v letu 2022 začeli uporabljati kot agregati v betonih. V letu 2023 je bila v okviru tekoče kontrole kakovosti ugotovljena nezadostna odpornost proti zmrzovanju betonov, in sicer tistih, v katerih je bil uporabljen agregat iz Liburnijske formacije. V okviru raziskovalnega dela je bil vzorčevan reprezentativni vzorec apnenca iz Liburnijske formacije. Iz njega so bile v laboratoriju pripravljene frakcije agregata za beton. Na kamnini in na frakcijah agregata so bile izvedene mehansko-fizikalne, geometrijske in kemijske preiskave. Izvedena je bila tudi mineraloško petrografska analiza, ki je v kamnini potrdila prisotnost organske komponente, bitumna in pirita. Da bi ugotovili vpliv agregata iz apnenca Liburnijske formacije na hidratacijo betona, so bili izdelani betoni z različno količino agregata. Ugotovljeno je bilo, da v betonu, ki vsebuje 100 mas. % agregata, superplastifikator ni deloval, zato je beton netransportabilen in nevgradljiv. Tudi aerant ni bil učinkovit, zato se ni razvil sistem umetnih por, ki zagotavlja odpornost betona proti zmrzovanju. Ta beton ima sicer najvišjo gostoto, najvišjo trdnost in najboljšo odpornost na prodor vode. Petrografska analiza betona kaže, da je agregat iz apnenca iz Liburnijske formacije zaradi primesi bitumna in drugih organskih komponent povzročil spremembe v mehanizmu strjevanja betona. Hidratacijski produkti se po sestavi niso spremenili, glavna produkta sta C-S-H gel in portlandit, vendar ju je v cementni matrici, zlasti na področju stika s temi agregatnimi zrni, očitno manj. Manj reakcijskih produktov pomeni višjo kapilarno poroznost matrice in razvoj stika s šibko kohezijo med zrni agregata in cementno matrico. Posledica je slaba odpornost betona proti zmrzovanju. Apnenec iz Liburnijske formacije torej ni primerna surovina za agregat za betone, saj z njim ni mogoče proizvesti kakovostnih in trajnih betonov.

• Language: Slovenian
• Keywords: apnenec iz Liburnijske formacije, organske primesi, agregat, beton, odpornost proti zmrzovanju
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Place of publishing: Ljubljana
• Publisher: J. Sevšek
• Year: 2026
• Number of pages: XV, 54 f.
• PID: 20.500.12556/RUL-183281
• UDC: 55
• COBISS.SI-ID: 281316611
• Publication date in RUL: 10.06.2026

Secondary language

• Language: English
• Title: Applicability of rocks from Liburnian formation for production of aggregate for concrete : master's thesis

Abstract

Along the route of the second railway track between Divača and Koper, in addition to flysch, several types of limestone appeared as excavation materials: alveolinid-nummulitic limestone, limestone of the Liburnian Formation, and limestone of the Trstelj Formation. Starting in 2022, these limestones began to be used as aggregates in concrete. In 2023, continuous quality control revealed insufficient freeze-thaw resistance in concretes containing aggregate from the Liburnian Formation. A representative sample of limestone from the Liburnian Formation was collected for research purposes. From this sample, concrete aggregate fractions were prepared in the laboratory. Mechanical-physical, geometrical, and chemical tests were carried out on the rock and on the aggregate fractions. A mineralogical-petrographic analysis was also performed, confirming the presence of organic components, bitumen, and pyrite in the rock. To determine the influence of this aggregate on concrete hydration, concretes containing different amounts of the aggregate were produced. It was found that in concrete containing 100 wt% of this aggregate, the superplasticizer was ineffective, making the concrete non-transportable and impossible to place. The air-entraining agent was also ineffective, and therefore an artificial air-void system, necessary for freeze-thaw resistance, did not develop. This concrete, however, exhibits the highest density, highest strength, and best resistance to water penetration. Petrographic analysis of the concrete shows that the aggregate from the Liburnian Formation, due to the presence of bitumen and other organic components, caused changes in the mechanism of concrete hardening. Although the composition of the hydration products did not change (the main products are C-S-H gel and portlandite), the amount of these products in the cement matrix, particularly in the interfacial zone with these aggregate grains, is clearly reduced. Fewer hydration products mean higher capillary porosity of the matrix and the formation of an interface with weak cohesion between the aggregate grains and the cement matrix. Consequently, the concrete exhibits poor freeze–thaw resistance. Limestone from the Liburnian Formation is therefore not a suitable raw material for concrete aggregate, as it cannot be used to produce high-quality, durable concrete.

• Keywords: limestone of the Liburnian Formation, organic impurities, aggregate, concrete, frost resistance.