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Ocena mikrobiologicznego wytrącania węglanów w procesie naprawy zapraw cementowych przy użyciu spektroskopii ramanowskiej

Janek Martyna, Fronczyk Joanna, Gieroba Barbara, Kalisz Grzegorz, Sroka-Bartnicka Anna, Franus Wojciech

Cement Wapno Beton

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2023

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R. 28, nr 5

301--317

PL

Zastosowanie mikroorganizmów stymulujących wytrącanie węglanów, które mogą wypełniać powstające w mikrostrukturze kompozytów cementowych spękania [MICP], zyskuje w ostatnich latach zainteresowanie jako alternatywny sposób samonaprawy tych materiałów. W artykule przeanalizowano efektywność powierzchniowej aplikacji środków naprawczych z zeolitu NaX i bentonitu, spor bakterii Bacillus subtilis oraz roztworów cementujących [prekursorów wytrącania] jako metody naprawy spękanych powierzchni zapraw cementowych. Efekty tej metody oceniono na podstawie analizy obrazu oraz badań mikrostruktury osadów wytrąconych w warunkach kontrolowanych i na powierzchniach zaleczonych kompozytów. Do charakterystyki mikrostruktury wykorzystano spektroskopię ramanowską oraz dyfrakcję rentgenowską XRD. Przeprowadzone badania potwierdziły wytrącanie węglanów w przełomie leczonych rys [maksymalnie 31,9 % zajęcia powierzchni przez wytworzony osad], co świadczy o efektywności zajścia procesu MICP, równocześnie wskazując na udział w mechanizmie wytrącania osadów abiotycznego wytrącania form krystalicznych obecnych w roztworach cementujących. Dodatkowo, potwierdzono efektywność zastosowania spektroskopii ramanowskiej do charakterystyki powierzchni kompozytu cementowego oraz węglanów wytrącanych przez mikroorganizmy.

EN

The use of microorganisms that stimulate the precipitation of carbonates, which can fill the cracks that form in the structure of cementitious composites [MICP], has been gaining interest in recent years as an alternative method of self-healing of these materials. This article analyses the effectiveness of surface application of repair agents composed of zeolite NaX and bentonite, Bacillus subtilis bacteria spores and cementing solutions [precursors of precipitation reactions] as a method of repairing cracked cement mortar surfaces. The effects of this method were evaluated by image analysis and microstructure studies of precipitates precipitated under controlled conditions and on the surfaces of healed composites. Raman spectroscopy and X-ray diffraction were used to characterize the microstructure. The conducted tests confirmed the precipitation of carbonates in the breakthrough of the healed cracks [maximum 31.9% occupation of the surface by the precipitate produced], which proves the effectiveness of the MICP process incident, at the same time indicating the participation in the mechanism of abiotic precipitation of crystalline forms present in the cementing solutions. Additionally, the effectiveness of using Raman spectroscopy to characterise the surface of the cement composite and the carbonates precipitated by microorganisms was confirmed.

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Efficiency comparison of mixture formulations in the stabilisation/solidification of the loess silt contaminated with zinc in terms of mechanical properties

Lal Agnieszka, Fronczyk Joanna, Franus Małgorzata

Budownictwo i Architektura

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2023

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Vol. 22, no 1

25--35

EN

The effectiveness of various types of binders in stabilizing/solidifying (S/S) contaminated soils is strongly dependent on the type of soil and contaminants present. The literature abounds with studies of stabilisation/solidification of clayey soils, which provides a background for initial assumptions in design of the method application for contamination of this type of soil. However, studies on the stabilisation/solidification of loess silt contaminated with heavy metals are not available. Filling this deficiency is important in order to ensure the rapid adoption of the most effective remedies in case of contamination and their immediate implementation in the subsoil. This paper has enabled the determination of the most effective mixture among the examined for the remediation of loess silt contaminated with zinc in terms of compressive strength. Strengths were determined with the implementation of 30% Portland cement (2.63 MPa), 30% of fly ash-cement mixture (2.21 MPa), an incinerated sewage sludge ash-cement mixture (0.93 MPa) and mixtures in which cement was replaced by an MgO activator (0.18 MPa for fly ash and 0.63 MPa for incinerated sewage sludge ash). In addition, the determination of strength was carried out for samples containing a mixture of fly ash, activator and cement (0.26 MPa) and incinerated sewage sludge ash, activator and cement (0.26 MPa), with weight ratios of 5:4:1 respectively. In summary, fly ash and cement in a 2:1 ratio can be considered the most effective binding mix in terms of unconfined compressive strength increase.

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Properties of Reactive Materials for Application in Runoff Water Treatment Systems

Fronczyk Joanna

Journal of Ecological Engineering

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2020

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Vol. 21, nr 8

185--197

EN

The emissions related to urbanized areas, including communication routes and accompanying facilities, are considered as essential sources of subsoil pollution. Enhancement of the naturally occurring removal processes in infiltration systems, e.g. through placing the appropriately selected materials (treatment zones) on the flow path of runoff water, prevents the spread of undesirable components. The article presents the analysis of tests checking the properties of selected low-cost mineral materials, activated carbon and zero-valent iron in terms of their applicability in the runoff water treatment zones. Their physical features, surface structure, and chemical and hydraulic properties were analysed. The test results indicate a well-developed surface area of active carbon and halloysite, as well as an extensive pore volume of active carbon, halloysite, zeolite and diatomite. Nevertheless, the average pore diameters indicated the potential limited access of pollutants to the inner structure of all analyzed materials. The chemical parameters point to the stimulation potential of precipitation processes by limestone sand and silica spongolite, ion exchange by zeolite and silica spongolite, and oxidation-reduction processes by zero-valent iron. The value of the material hydraulic conductivity may potentially limit their application in infiltration systems. Taking into account all analyzed parameters, activated carbon together with silica spongolite and zeolite have the best application potential.