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Experimental carbonation study for durability assessment of novel cementitious materials
Sebastijan Robič, Aljoša Šajna, Lucija Hanžič, Alisa Machner, Marie Helene Bjørndal, Klaartje De Weerdt, Yushan Gu, Benoit Bary, Rosamaria Lample, 2021, published scientific conference contribution

Abstract: The design process of concrete structures is carried out using standards and guidelines, while the durability predictions of concrete structures is supported only with exposure classes and experience-based requirements. To improve durability predictions of the carbonation resistance of concrete, a numerical model is being developed within the Horizon 2020 project EnDurCrete, coupling the rate of carbonation, and the drying rate. To verify the numerical model, an accelerated carbonation study was carried out. Experiments were conducted on mortars incorporating a novel CEM II/C (S-LL) cement, developed within the EnDurCrete project, and a commercially available reference cementCEM II/A-S. EnDurCrete mortars (EnM) and reference mortars (RefM) were prepared with water-cement ratios of 0.6 and 0.5 (denoted with label extensions -06 and -05). Visual assessments and thermogravimetric analysis (TGA) were used to measure the carbonation rates, which were found to be ~1.0 mm day-0.5 in EnM-06 and ~0.6 mm day-0.5 in RefM-06, while in EnM-05 and RefM-05 the values were ~0.7 and ~0.2 mm day-0.5 respectively. Additionally, TGA shows that the initial portlandite (CH) content is ~1.5 wt% in EnM-06 as opposed to ~3.0 wt% in RefM-06. The difference in the initial CH content in the two hydrated binders might explain the difference in their carbonation rate. During the moisture transport experiments a gravimetric method was used to determine mass changes as specimens underwent drying and resaturation with and without CO2 present. The drying led to a decrease in mass, but in the presence of CO2 this mass loss was compensated by the mass gain due to uptake of CO2 during carbonation. The resaturation experiments indicate an increase in the suction porosity in the carbonated samples compared to the non-carbonated samples.
Keywords: concrete, absorption of water, carbonation, durability assessment, model verification
Published in DiRROS: 25.01.2024; Views: 141; Downloads: 97
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4.
Measurement of the chloride resistance of environmentally friendly and durable concrete
Alisa Machner, Marie Helene Bjørndal, Aljoša Šajna, Lucija Hanžič, Yushan Gu, Benoit Bary, Klaartje De Weerdt, 2020, published scientific conference contribution

Abstract: The increasing demand for concrete and thereby Portland cement, creates the need for novel low-clinker Portland composite cements. Concretes prepared with such novel composite cements need to show similar or even improved durability compared to concrete prepared with commonly used Portland composite cements. This study represents a part of the EnDurCrete project that focuses on the durability of concrete produced with novel low-clinker cements, containing high-value industrial by-products. More specifically, we investigated the chloride ingress resistance of such concrete. Concrete cylinders were submitted to chloride ingress by bulk diffusion. The chloride ingress resistance was investigated on concrete samples by %XRF scanning and chloride titration. In addition, the chloride binding capacity of these novel binders was investigated on paste samples by determining chloride binding isotherms for both binders. In the next step of the project, these experimental results will be matched with an advanced model, which is being developed within the project. By combining modelling with experimental verification, we aim to reach a better understanding of the fundamental chloride ingress mechanisms acting on novel types of concrete. The overall goal of the work is to produce a concrete with lower cost, lower environmental footprint and with verified similar or improved durability.
Keywords: chloride ingress, durability, novel binders, Low C02, sustainability, concrete
Published in DiRROS: 19.01.2024; Views: 156; Downloads: 75
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Experimental and numerical investigation of restrained shrinkage of concrete
Lucija Hanžič, Jurij Karlovšek, Tomaž Hozjan, Sabina Huč, Zhongyu Xu, Igor Planinc, Johnny Ching Ming Ho, 2020, published scientific conference contribution

Abstract: To promote the understanding of shrinkage related behaviour of concrete used for tunnel linings the experimental and theoretical investigation including numerical and analytical approach was performed on ring-shaped specimens. Overall one analytical (an.) and two numerical models, namely (i) and (ii) were also developed. Models (an.) and (i) considered the restraining steel ring to be rigid, thus not exhibiting any deformation. Numerical model (ii) considered the steel ring to be deformable. The experimental set-up consisted of a large concrete ring with an inner diameter of 120 cm, an outer diameter of 160cm and 20 cm in height. The restraining steel ring was 5.5 cm thick. Two concrete rings were made, namely R1 with a low compressive strength of ~26MPa and the other, R2, with medium compressive strength of ~40 MPa. The strain was measured in the hoop direction on the inner circumference of the steel ring and on the outer circumference of the concrete ring. Concrete rings were subjected to circumferential drying. Numerical model (ii) predicted critical time to the formation of the first crack to be between 13 and 14 days. The experimentally determined critical time is found to be 11 to 13 days with cracks gradually opening over several days. This was indicated by changes in measured concrete and steel strain. Modelled concrete strain just before cracking was between -20 and -30 % 10-6 m m-1 however, measured concrete strain was ~150 % 10-6 m m-1. Modelled steel strain was between -30 and -40 % 10-6 m m-1 while measured steel strain was between -10 and 20 % 10-6 m m-1. These discrepancies, in particular the positive steel strain obtained in experiments, require further investigation and improvements of the experimental set-up.
Keywords: concrete, tunnel lining, restrained shrinkage, Reissner beam theory, modelling
Published in DiRROS: 19.01.2024; Views: 152; Downloads: 68
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Ribiške zgodbe v šoli : priročnik za učitelje tretje triade osnovnih šol
Lucija Čok, Tina Čok, Urška Bratož, Irina Moira Cavaion, Anna Maria Grego, 2023, dictionary, encyclopaedia, lexicon, manual, atlas, map

Abstract: Priročnik Ribiške zgodbe v šoli je namenjen predvsem osnovnošolskim učiteljicam in učiteljem tretje triade, ki bi želeli dopolniti, razširiti in poglobiti vsebine, predvidene v okviru nekaterih obveznih in izbirnih predmetov (etnologija – kulturna dediščina in načini življenja, zgodovina – odkrivajmo preteklost svojega kraja, geografija – raziskovanje domačega kraja (šolskega okoliša) in varstvo njegovega okolja, pa tudi slovenščina in italijanščina …). Ker je bilo ob omenjeni analizi obstoječih učnih načrtov mogoče opaziti izrazito pomanjkanje vsebin, povezanih z (morskim) ribištvom in življenjem ob morju, so v nadaljevanju navedeni nekateri predlogi za intenzivnejše vključevanje obmorskih vsebin v učni proces. Opisani so primeri tematsko prepletenih, toda ločenih učnih enot (o ribištvu, ribiški dediščini, zgodovini predelave rib v obmorskih mestih, terminologiji, povezani z ribištvom, kulinariki v povezavi s floro in favno Sredozemlja in podobne teme), v katerih so poleg okvirne vsebine določeni tudi operativni cilji, način dela, možnosti medpredmetnih povezav ter dodatna gradiva in delovni listi za uspešen izobraževalni proces, kar učiteljicam in učiteljem olajša pripravo učnih ur, načrtovanje projektnega dela in tudi dodatnih pedagoških dejavnosti. Seveda so ti predlogi navedeni samo kot smernice, ki jih učiteljice in učitelji lahko poljubno preoblikujejo.
Keywords: prehrambna kultura, prehrambna industrija, ribe, konzerviranje
Published in DiRROS: 18.07.2023; Views: 343; Downloads: 204
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7.
Experimental carbonation study for a durability assessment of novel cementitious materials
Lucija Hanžič, Sebastijan Robič, Alisa Machner, Marie Helene Bjørndal, Klaartje De Weerdt, Yushan Gu, Benoit Bary, Rosa Maria Lample Carreras, Aljoša Šajna, 2021, original scientific article

Abstract: Durability predictions of concrete structures are derived from experience-based require- ments and descriptive exposure classes. To support durability predictions, a numerical model related to the carbonation resistance of concrete was developed. The model couples the rate of carbonation with the drying rate. This paper presents the accelerated carbonation and moisture transport exper- iments performed to calibrate and verify the numerical model. They were conducted on mortars with a water-cement ratio of either 0.6 or 0.5, incorporating either a novel cement CEM II/C (S-LL) (EnM group) or commercially available CEM II/A-S cement (RefM group). The carbonation rate was determined by visual assessment and thermogravimetric analysis (TGA). Moisture transport experi- ments, consisting of drying and resaturation, utilized the gravimetric method. Higher carbonation rates expressed in mm/day−0.5 were found in the EnM group than in the RefM group. However, the TGA showed that the initial portlandite (CH) content was lower in the EnM than in the RefM, which could explain the difference in carbonation rates. The resaturation experiments indicate an increase in the suction porosity in the carbonated specimens compared to the non-carbonated specimens. The study concludes that low clinker content causes lower resistance to carbonation, since less CH is available in the surface layers; thus, the carbonation front progresses more rapidly towards the core.
Keywords: mortar, absorption of water, carbonation, durability assessment, model verification
Published in DiRROS: 05.07.2023; Views: 259; Downloads: 161
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8.
Engineered combinatorial cell device for wound healing and bone regeneration
Lucija Kadunc, Duško Lainšček, Rok Gašperšič, Petra Sušjan, Uroš Kovačič, Miha Butinar, Boris Turk, Roman Jerala, Iva Hafner Bratkovič, 2023, original scientific article

Abstract: Growth factors are the key regulators that promote tissue regeneration and healing processes. While the effects of individual growth factors are well documented, a combination of multiple secreted growth factors underlies stem cell–mediated regeneration. To avoid the potential dangers and laborintensive individual approach of stem cell therapy while maintaining their regeneration-promoting effects based on multiple secreted growth factors, we engineered a “mix-and-match” combinatorial platform based on a library of cell lines producing growth factors. Treatment with a combination of growth factors secreted by engineered mammalian cells was more efficient than with individual growth factors or even stem cell–conditioned medium in a gap closure assay. Furthermore, we implemented in a mouse model a device for allogenic cell therapy for an in situ production of growth factors, where it improved cutaneous wound healing. Augmented bone regeneration was achieved on calvarial bone defects in rats treated with a cell device secreting IGF, FGF, PDGF, TGF-β, and VEGF. In both in vivo models, the systemic concentration of secreted factors was negligible, demonstrating the local effect of the regeneration device. Finally, we introduced a genetic switch that enables temporal control over combinations of trophic factors released at different stages of regeneration mimicking the maturation of natural wound healing to improve therapy and prevent scar formation.
Keywords: wound healing, bone regeneration, growth factors
Published in DiRROS: 01.06.2023; Views: 458; Downloads: 179
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9.
Agresivnost ploščatocelične komponente bazalnoceličnega karcinoma vulve : klinični primer
Lucija Bogdan, Janja Ocvirk, 2023, published scientific conference contribution

Abstract: Bazalnocelični karcinom kože je najpogostejši nemelanomski kožni rak. Zaseva izjemno redko, možne so lokalne ponovitve bolezni in invazivna rast. Tveganje za lokalno ponovitev je odvisno od histopatološkega podtipa. Keratotični podtip vsebuje ploščatocelično komponento. Karcinom najpogosteje vznikne na soncu izpostavljenih mestih, redko na predelu ženskega zunanjega spolovila. V literaturi so bili doslej opisani posamezni primeri razsoja bazalnoceličnega karcinoma vulve v ingvinalne bezgavke. Lokalno napredovali, recidivantni in metastatski bazalnocelični karcinom kože zdravimo z vismodegibom, v 2. liniji ali ob neprenašanju z zaviralcem imunskih kontrolnih točk cemiplimabom. Cemiplimab je indiciran tudi pri lokalno napredovalem in metastatskem ploščatoceličnem karcinomu kože. V približno 10% se pri zdravljenju pojavijo revmatološki neželeni učinki, imunski pogojeni diabetes je zelo redek. Predstavljen je primer 53-letne bolnice s keratotičnim podtipom bazalnoceličnega karcinoma vulve z dokazanim razsojem s prevladujočo ploščatocelično komponento v ingvinalne in retroperitonealne bezgavke. Zdravljena je bila z vismodegibom in s cemiplimabom. Med zdravljenjem s cemiplimabom je razvila imunsko povzročeni diabetes s ketoacidozo, atralgije in mialgije.
Keywords: rak kože, melanom, sistemsko zdravljenje
Published in DiRROS: 18.05.2023; Views: 336; Downloads: 136
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10.
Effect of leaching on the composition of hydration phases during chloride exposure of mortar
Alisa Machner, Marie Helene Bjørndal, Harald Justnes, Lucija Hanžič, Aljoša Šajna, Yushan Gu, Benoit Bary, Mohsen Ben Haha, Mette R. Geiker, Klaartje De Weerdt, 2022, original scientific article

Abstract: Mortar specimens were exposed to either a 3% NaCl solution or a 3% NaCl+KOH solution for up to 180 days. Exposure to the NaCl solution provoked much more leaching than the NaCl+KOH exposure. Leaching strongly impacted the chloride ingress profiles. The extended leaching led to a maximum total chloride content almost three times higher and a deeper chloride penetration than exposure with limited leaching after 180 days. The higher maximum chloride content seems to be linked to the enhanced binding capacity of the C-S-H and AFm phases upon moderate leaching as determined by SEM-EDS. The total chloride profile appears to be governed by multi-ion transport and the interaction of chloride with the hydration phases. Service life prediction and performance testing both rely on total chloride profiles and therefore ought to take these interactions into account.
Keywords: chloride binding, Friedel's salt, Kuzel's salt, ph, GEMS, thermodynamic modelling, open access
Published in DiRROS: 26.04.2023; Views: 294; Downloads: 246
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