The use of ultrasonic measurement in determining the quality of natural stone blocks – limestone

Kos, Andrej (author), Kortnik, Jože (mentor)

Natural stone or architectural building stone, as it is also termed, is a specific raw material, the extraction of which requires the use of specific technology. The size of the quarries of natural stone is measured by the quantity of the stone blocks produced, which must be as compact as possible. To date, the compactness of stone blocks or monoliths has been controlled through various methods. Most often, the only method of testing the quality of blocks has been by listening to the echoes stone emited after being hit by another stone or by performing visual checks of the material. The development of ultrasonic technologies, particularly the use of the ultrasonic impulse method, enables us to review the quality of a stone specimen by analyzing the obtained data. Compactness is determined through the application of the tomography method. Stone blocks from the quarry contain hidden discontinuities. The technique of capturing data using ultrasonic instruments provides a good insight into the interior of the block. By developing a specific methodology for determining the compactness of the stone block and implementing a large number of measurements, we have devised a special classification of compactness, which enables the reduction of processing costs and improvement in the quality of stone blocks. The compactness control methodology is based on a non-destructive transition of longitudinal "ultrasonic" waves over a stone block profile. The measured differences in velocities indicate faults in the stone block. Having applied a specially developed measurement methodology and analysed the data obtained, we created a tomographic profile of the measured profile, which reveals possible locations of irregularities we must avoid or pay special attention to in further processing. In-situ control measurements of stone blocks provide additional data, which are compared against the results of ultrasonic measurements. Determining critical locations in stone blocks is of great importance in their further processing into various stone products, as well as in the reconstruction of old stone elements or sculptures. Such an evaluation of the block enables us to complete project tasks faster and, in terms of economics, facilitates a more rational use of the material. The developed methodology for determining compactness is quick and easy to carry out and provides effective assistance in assessing the quality of stone blocks.

• Language: English
• Keywords: dimension stone, ultrasonic method, stone blocks, compactness classification
• Work type: Doctoral dissertation
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Year: 2019
• PID: 20.500.12556/RUL-107441
• COBISS.SI-ID: 1803615
• Publication date in RUL: 13.04.2019

Secondary language

• Language: Slovenian
• Title: Uporaba ultrazvočnih meritev pri določevanju kvalitete blokov naravnega kamna – apnenca

Abstract

Naravni kamen ali okrasni arhitektonski gradbeni kamen, kot ga radi imenujejo, je specifična mineralna surovina, ki se pridobiva s specifično tehnologijo. Velikost kamnolomov naravnega kamna se meri v količini proizvedenih kamnitih blokov, ki morajo biti čim bolj kompaktni. Kompaktnost kamnitih blokov oz. monolitov se je v preteklosti kontrolirala z različnimi metodami. Največkrat so temeljile na lastnih izkušnjah preizkuševalca, zvočnih in vizualnih opazovanjih materiala. Z razvojem tehnologij se za pregled kvalitete kamnitih preizkušancev danes vse več uporablja ultrazvočna impulzna metoda in z analizo pridobljenih podatkov, se z metodo tomografije ugotavlja kompaktnost. Kamniti bloki, ki prihajajo iz nahajališča vsebujejo nam skrite diskontinuitete. Tehnika zajema podatkov z uporabo ultrazvočnih instrumentov omogoča dober vpogled v notranjost bloka. Z izdelavo posebne metodologije določanja kompaktnosti kamnitega bloka in izvedbi obsežnega števila meritev smo razvili posebno klasifikacijo kompaktnosti, ki omogoča zmanjšanje stroškov predelave in izboljšanje kvalitete kamnitih blokov. Metodologija kontrole kompaktnosti temelji na ne rušilnem prehodu longitudinalnih »ultrazvočnih« valov preko kamnitega bloka. Izmerjene razlike v hitrostih nakazujejo nepravilnosti v kamnitem bloku. S posebej razvito metodologijo meritev in analizo pridobljenih podatkov izdelamo tomografski profil meritev, ki nam pokaže na morebitne lokacije nepravilnosti, katerim se moramo izogniti ali pri nadaljnjem predelavi posveti posebno pozornost. Pri in-situ kontrolnih meritvah blokov pridobimo dodatne podatke, ki jih primerjamo z izmerjenimi rezultati ultrazvočnih meritev. Določitev kritičnih lokacij oz. nepravilnosti v kamnitem bloku je velikega pomena pred nadaljnjo predelavo v različne kamnite izdelke ali pri rekonstrukciji starih kamnitih elementov ali skulptur. Ovrednotenje bloka nam omogoča hitrejše izdelavo zadanih projektnih nalog in iz vidika ekonomičnosti omogoča racionalnejšo izrabo materiala. Razvita metodologija določanja kompaktnosti je hitra in enostavna za izvedbo ter učinkovita pomoč pri oceni kvalitete bloka.

• Keywords: naravni kamen, ultrazvočna metoda, kamniti bloki, klasifikacija kompaktnosti