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Abstract: This paper investigates the effectiveness of a specific crystalline waterproofing admixture (CWA) in concrete as a function of a water–binder ratio. Four concrete mixes with and without CWA were prepared; two of them with a water–binder ratio of 0.45 and two of them with a water– binder ratio of 0.55. Water permeability and compressive strength were tested on hardened concrete specimens and self-healing of cracks over time was observed. Cement paste and CWA paste were prepared to clarify the results obtained on the concrete specimens. SEM and EDS and XRD and FTIR were performed on the hardened pastes to explain the mechanism of CWA working. The results show that the addition of CWA had no significant effect on the compressive strength of the concrete, but reduced the water penetration depth in the concrete, and the reduction was more effective for mixes with lower water–binder ratio. Regarding the self-healing effect, it can be concluded that the addition of CWA improves the crack healing in concrete, but the efficiency of self-healing is highly dependent on the initial crack width. The mechanisms involved in the reduction of water penetration depth and crack healing in concrete can be explained by different mechanisms; one is creation of the CSH gel from unreacted clinker grains, then formation carbonate, and additional mechanism is gel formation (highly expansive Mg-rich hydro-carbonate) from magnesium based additives. The presence of sodium silicate, which would transform into carbonate/bicarbonate, also cannot be excluded.
Keywords: slag, self healing concrete, crystal admixture, microstructural analysis
Published in DiRROS: 03.07.2023; Views: 277; Downloads: 198
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Published in DiRROS: 20.06.2023; Views: 329; Downloads: 134
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Abstract: Obsevanje je del standardnega zdravljenja bolnic z rakom dojk. Odgovor na zdravljenje z obsevanjem je pri vsakem posamezniku drugačen in je odvisen tudi od genetskih dejavnikov. Eden od novejših genetskih označevalcev odgovora na obsevanje je dolžina telomerov. Telomeri ščitijo kromosome pred krajšanjem in vzdržujejo genomsko stabilnost. Rezultati naše raziskave kažejo, da se dinamika spreminjanja dolžine telomerov takoj po zdravljenju z obsevanjem in v šestih mesecih po obsevanju pri bolnicah z neinvazivnim rakom dojk spreminja in bi lahko služila kot biološki označevalec odgovora na obsevanje. Molekularni mehanizmi, povezani s tem procesom, ostajajo zaenkrat večinoma neraziskani.
Keywords: rak dojk, obsevanje, onkološko zdravljenje
Published in DiRROS: 16.06.2023; Views: 349; Downloads: 138
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Keywords: varstvo gozdov, morfološke analize, rdeči bor, osip borovih iglic, Lophodermium seditiosum, siva plesen, Botrytis cinerea, sušica najmlajših borovih poganjkov, Diplodia pinea, ekološke razmere, vlažnost zraka
Published in DiRROS: 06.06.2023; Views: 324; Downloads: 73
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Abstract: Temperature control is the primary concern during the design and construction process of mass concrete structures. As the concrete production has an enormous negative environmental impact, the development of green mass concretes will eventually become as important as the thermal characteristics. Therefore, this paper investigates the use of Electric Arc Furnace (EAF) steel slag aggregate for the partial replacement of the natural aggregate in the production of mass concrete. The impact of EAF steel aggregate on mass concrete workability, strength, and thermal behaviour was analysed. In addition, a cradle-to-gate LCA study was conducted to evaluate the environmental footprint and sustainability potential of the tested mass concrete mixtures. The study results suggest that the use of EAF steel slag aggregate in combination with a low-heat cement with a high content of blast furnace slag can significantly lower the temperature, reduce the environmental impact, and increase the sustainability potential of mass concrete, while at the same time providing sufficient workability and compressive strength. The study results indicate that EAF steel slag can be upcycled into an aggregate for the production of green mass concrete mixtures.
Keywords: mass concrete, thermal stress, EAF steel slag, green concrete, LCA, sustainability, open access
Published in DiRROS: 31.05.2023; Views: 295; Downloads: 210
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