Determination of the effects of the rebar-cement bond parameters variation in UHPFRC using FA and ANN

The experimental study included the design and production of ultra-high-performance steel fiber-reinforced concrete (UHPFRC). The physical and mechanical properties of UHPFRC were investigated in a laboratory setting. To investigate the properties of UHPFR concrete, three types of concrete and over 70 samples were used. Following that, samples were created to test the anchors' load-bearing performance. Six concrete slabs with a total of 108 pre-installed anchor samples and six concrete slabs with 108 post-installed chemical anchor samples were created. The analysis of the test findings comprised all individual results as well as the definition of the relationship between the anchor's tensile load capacity and other parameters. To accurately determine the individual influence of the investigated factors as well as their combined impact, a factorial experiment, and artificial neural networks were used in addition to normal statistical numerical studies. It was determined that both approaches offer advantages. The results obtained show matches in certain parts. Due to the way data is processed in different ways, there are also significant differences between them

KORIŠTENJE PALEORADIOLOŠKE I MIKROBIOLOŠKE ANALIZE ANTIČKOGA KULTURNOG MATERIJALA: MSCT, MAMOGRAFIJA I MIKROBIOLOŠKA ANALIZA KAPULJAČE S LIKOM SV. MARTINA I PROSJAKA (TROGIR, HRVATSKA)

Paleoradiology is the study of biological and other materials from archeological settings through the use of various medical imaging techniques. Although it is most often used in the scientific study of ancient human remains, it can also be used to study metals, ceramics, paper, and clothes. The aim of this study was to test two paleoimaging techniques (MSCT and mammography) in the analysis of an important Croatian liturgical vestment: the hood of a bishop’s cope from St. Lawrence’s Treasury in Trogir depicting St. Martin and a beggar. To ensure a safe environment for scientists participating in the analysis, a preliminary microbiological analysis was performed, which contributed to the database of microbiological flora found on Croatian archeological remains and relics studied to date. Due to a great amount of metal filaments, the paleoradiological analysis did not produce satisfactory results. However, a digitally enhanced image clearly showed fine metal embroidery of the hood that was not so easily perceived by naked eye. This article argues in favor of expanding paleoradiological studies on materials other than human remains and also of publishing unsatisfactory results, as important lessons for future development of techniques and methods to analyze ancient remains and seek answers about human historical and cultural heritage.Paleoradiologija je znanstvena disciplina koja se u analizi arheološki značajnih bioloških i drugih materijala služi različitim medicinskim slikovnim metodama. Iako se danas najčešće primjenjuje u istraživanju ljudskih ostataka, paleoradiologija se može koristiti i u analizi metala, keramike, papira i odjeće. Cilj je ovoga rada prikazati rezultate paleoradiološke (MSCT i mamografske) analize značajnoga hrvatskog obrednog crkvenog ruha: kapuljače biskupskog plašta s likom sv. Martina i prosjaka iz Trogirske riznice. Da bi se istraživačima osigurali sigurni uvjeti rada, izvedeno je mikrobiološko testiranje plašta, kojim su se nadopunili dosadašnji podaci o mikrobiološkoj flori hrvatskih arheoloških ostataka i relikvija. Zbog velikog broja metalnih niti prisutnih u kukuljici, paleoradiološka analiza nije dala zadovoljavajuće rezultate. Ipak, digitalno poboljšanje slike omogućilo je bolje uočavanje samog stila figuralnoga metalnog veza kapuljače, koji je teže uočiti golim okom. Naposljetku, studija obrazlaže značenje paleoradiologije u proučavanju nehumanoga arheološkog materijala kao i objavljivanje rezultata koji nisu posve zadovoljavajući, a bitni su za daljnji razvoj i poboljšavanje tehnika koje se koriste u istraživanju i arheološkog materijala i ljudske povijesti

Properties of concrete with crumb rubber in relation to ordinary and aerated concrete

Waste tires have long been a challenge for waste disposal. In an effort to mitigate the impact of solid waste on the environment and recycle it as much as possible, research has been conducted into the possibility of using this waste in concrete mixes. However, the use of these waste materials in concrete is still not popular due to the lack of knowledge of the properties that can be obtained with this material. Hence, the aim is to use waste material in the production of concrete, and that concrete mixes with this material have satisfactory performance. The paper presents the results of research on concrete in which volume replacement of fine aggregate with crumb rubber was performed in the amount of 5%, and this concrete was compared with the control concrete mix and aerated concrete. All concrete are made with a water-cement factor of 0.45. The performance of fresh concrete was monitored for 10, 30 and 60 min. In the case of concrete with the addition of crumb rubber, after 60 min, higher values of air content were obtained, and lower values of volume mass of fresh concrete compared to the initial measurements. The obtained test results of hardened concrete indicate that concrete with crumb rubber has a lower compressive strength compared to the control concrete mix, while compared to aerated concrete, they obtain approximate compressive strength values

Comparison of gamma and X radiation attenuation characteristics for ordinary concrete, concrete with barite and concrete with limonite and steel

During 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.RAP 2023 : International conference on radiation applications in Physics, Chemistry, Biology, Medical Sciences, Engineering and Environmental Sciences; Book of abstracts; May 29 - June 2, 2023, Anavyssos, Greec

Investigation of the Mechanical Properties of Concrete Incorporating Recycled Rubber Particles

Quantity of waste rubber generated by automobile tires is growing, posing an environmental threat. Rubber tire recycling was studied for usage in asphalt and waterproofing systems during past few decades. Globally, concrete is the most widely used building material. About 7% of CO2 emissions come from the cement production. The purpose of this research is to assess if using waste rubber and Portland cement together in composite material for structural applications is feasible. Waste tires (shredded to 0/1 mm) were used as fine aggregate replacement (in 2.5 and 7.5 %), together with PC and natural stone. An investigation of properties in fresh (slump test, bulk density, air content) and hardened state (bulk density, compressive strength) was performed on the rubberized concrete. The compressive strength decreased by increasing the rubber content for all w/c ratios (0.55-0.4). The addition of fine-sized rubber did not cause a retardation in cement hydration mechanism. According to the obtained compressive strengths, all designed rubberized concretes belong to a group of structural concretes

Heavyweight Ultra-High-Performance Concrete with Micro-Reinforcement

The impacts of nano-silica addition, steel micro-reinforcement, and aggregate type on the mechanical properties and durability of ultra-high-performance concrete (UHPC) were studied. As aggregates, quartz and barite were used. The amounts of steel fibers and nanosilica were alternated. Six concrete mixes were produced with quartz sand, and the remaining six concrete mixes were designed with barite sand. Fibers made about 3-5% of the concrete composition’s mass. In a 2-5% concentration, nano-silica was used as a cement replacement. The inclusion of nano-silica significantly boosted the compressive strength of UHPC. The compressive and flexural strengths were also positively impacted by fiber supplementation ranging from 3% to 5%. The amount of fiber utilized proved to be more influential than the aggregate used. The UHPC concrete's durability was increased as all samples were highly resistant to freezing and thawing cycles. UHPC designed with barite aggregate demonstrated good X and gamma ray absorption at energies below 300 keV

THE USE OF PALEO-IMAGING AND MICROBIOLOGICAL TESTING IN THE ANALYSIS OF ANTIQUE CULTURAL MATERIAL: MULTISLICE COMPUTER TOMOGRAPHY, MAMMOGRAPHY, AND MICROBIAL ANALYSIS OF THE TROGIR CATHEDRAL COPE HOOD DEPICTING ST. MARTIN AND A BEGGAR

Paleoradiologija je znanstvena disciplina koja se u analizi arheološki značajnih bioloških i drugih materijala služi različitim medicinskim slikovnim metodama. Iako se danas najčešće primjenjuje u istraživanju ljudskih ostataka, paleoradiologija se može koristiti i u analizi metala, keramike, papira i odjeće. Cilj je ovoga rada prikazati rezultate paleoradiološke (MSCT i mamografske) analize značajnoga hrvatskog obrednog crkvenog ruha: kapuljače biskupskog plašta s likom sv. Martina i prosjaka iz Trogirske riznice. Da bi se istraživačima osigurali sigurni uvjeti rada, izvedeno je mikrobiološko testiranje plašta, kojim su se nadopunili dosadašnji podaci o mikrobiološkoj flori hrvatskih arheoloških ostataka i relikvija. Zbog velikog broja metalnih niti prisutnih u kukuljici, paleoradiološka analiza nije dala zadovoljavajuće rezultate. Ipak, digitalno poboljšanje slike omogućilo je bolje uočavanje samog stila figuralnoga metalnog veza kapuljače, koji je teže uočiti golim okom. Naposljetku, studija obrazlaže značenje paleoradiologije u proučavanju nehumanoga arheološkog materijala kao i objavljivanje rezultata koji nisu posve zadovoljavajući, a bitni su za daljnji razvoj i poboljšavanje tehnika koje se koriste u istraživanju i arheološkog materijala i ljudske povijesti.Paleoradiology is the study of biological and other materials from archeological settings through the use of various medical imaging techniques. Although it is most often used in the scientific study of ancient human remains, it can also be used to study metals, ceramics, paper, and clothes. The aim of this study was to test two paleoimaging techniques (MSCT and mammography) in the analysis of an important Croatian liturgical vestment: the hood of a bishop’s cope from St. Lawrence’s Treasury in Trogir depicting St. Martin and a beggar. To ensure a safe environment for scientists participating in the analysis, a preliminary microbiological analysis was performed, which contributed to the database of microbiological flora found on Croatian archeological remains and relics studied to date. Due to a great amount of metal filaments, the paleoradiological analysis did not produce satisfactory results. However, a digitally enhanced image clearly showed fine metal embroidery of the hood that was not so easily perceived by naked eye. This article argues in favor of expanding paleoradiological studies on materials other than human remains and also of publishing unsatisfactory results, as important lessons for future development of techniques and methods to analyze ancient remains and seek answers about human historical and cultural heritage

THE USE OF PALEO-IMAGING AND MICROBIOLOGICAL TESTING IN THE ANALYSIS OF ANTIQUE CULTURAL MATERIAL: MULTISLICE COMPUTER TOMOGRAPHY, MAMMOGRAPHY, AND MICROBIAL ANALYSIS OF THE TROGIR CATHEDRAL COPE HOOD DEPICTING ST. MARTIN AND A BEGGAR

Paleoradiologija je znanstvena disciplina koja se u analizi arheološki značajnih bioloških i drugih materijala služi različitim medicinskim slikovnim metodama. Iako se danas najčešće primjenjuje u istraživanju ljudskih ostataka, paleoradiologija se može koristiti i u analizi metala, keramike, papira i odjeće. Cilj je ovoga rada prikazati rezultate paleoradiološke (MSCT i mamografske) analize značajnoga hrvatskog obrednog crkvenog ruha: kapuljače biskupskog plašta s likom sv. Martina i prosjaka iz Trogirske riznice. Da bi se istraživačima osigurali sigurni uvjeti rada, izvedeno je mikrobiološko testiranje plašta, kojim su se nadopunili dosadašnji podaci o mikrobiološkoj flori hrvatskih arheoloških ostataka i relikvija. Zbog velikog broja metalnih niti prisutnih u kukuljici, paleoradiološka analiza nije dala zadovoljavajuće rezultate. Ipak, digitalno poboljšanje slike omogućilo je bolje uočavanje samog stila figuralnoga metalnog veza kapuljače, koji je teže uočiti golim okom. Naposljetku, studija obrazlaže značenje paleoradiologije u proučavanju nehumanoga arheološkog materijala kao i objavljivanje rezultata koji nisu posve zadovoljavajući, a bitni su za daljnji razvoj i poboljšavanje tehnika koje se koriste u istraživanju i arheološkog materijala i ljudske povijesti.Paleoradiology is the study of biological and other materials from archeological settings through the use of various medical imaging techniques. Although it is most often used in the scientific study of ancient human remains, it can also be used to study metals, ceramics, paper, and clothes. The aim of this study was to test two paleoimaging techniques (MSCT and mammography) in the analysis of an important Croatian liturgical vestment: the hood of a bishop’s cope from St. Lawrence’s Treasury in Trogir depicting St. Martin and a beggar. To ensure a safe environment for scientists participating in the analysis, a preliminary microbiological analysis was performed, which contributed to the database of microbiological flora found on Croatian archeological remains and relics studied to date. Due to a great amount of metal filaments, the paleoradiological analysis did not produce satisfactory results. However, a digitally enhanced image clearly showed fine metal embroidery of the hood that was not so easily perceived by naked eye. This article argues in favor of expanding paleoradiological studies on materials other than human remains and also of publishing unsatisfactory results, as important lessons for future development of techniques and methods to analyze ancient remains and seek answers about human historical and cultural heritage