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Exterior plasters can be disturbed by biological biofilms. A significant part of the biofilms are green algae. Present chemical preparations for protection of plasters against algae are mostly base on artificial chemicals those can be very often persistent and danger. It is necessary to find new, more natural biocidal substances and mixtures. In the present study, five selected botanicals (thyme oil, cinnamon oil, thymol, carvacrol, eugenol) was tested for their antialgal properties in aquatic test with biofilm isolated from lime plaster. The botanicals were dissolved in an organic solvent dimethysulfoxide (DMSO). The tests were performed in plastic microplates under laboratory conditions in a biological incubator for 14 days. The total inhibition concentration (TIC) was a measured endpoint. The tests with concentrations in range of 200 to 25 mg/L and 0 mg/L were performed. The own solvent was not toxic to biofilm. The results did not show TIC effects for cinnamon oil in the tested range of concentrations. TIC values were observed in the case of thymol and thyme oil (200-100 mg/L) and eugenol or carvacrol (25 mg/L).

This paper presents the possibilities of using light microscopy (LM), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) to characterize historical lime-based plasters from the first half of the 20th century. The paper compares these methods and evaluates the advantages and limitations of each technique. The experiments carried out showed that, in addition to determining the elemental composition in specific layers and phases of the plaster, other important information can be analyzed by electron microscopy. It is also possible to identify admixtures or detect cracks, which is necessary to assess the effect of aging on the plaster and ensure its proper renovation.

This research investigates the feasibility of developing clay composites using natural materials and incorporating waste by-products suitable for plastering diverse support structures. The study identified a versatile composition suitable for a wide range of support materials and explored the potential of revaluing industrial waste and by-products by reintegrating them into the Circular Economy. The experimental investigation outlines the process of evaluating the influence of different raw materials on the performance of the clay composite. The findings confirm that using limestone sludge and fly ash as additives to clay contributes to reducing axial shrinkage and increasing mechanical strengths, respectively. The optimal percentage of additives for the clay used are identified and provided. Using hydraulic lime as a partial substitute for clay reduces the apparent density of dried clay composites, axial shrinkage, and fissures formation while improving adhesion to the substrate. Introducing dextrin into this mix increases the apparent density of the hardened plaster while keeping axial shrinkage below the maximum threshold indicated by the literature. Mechanical strengths improved, and better compatibility in terms of adhesion to the support was achieved, with composition S3 presenting the best results and a smooth, fissure-free plastered surface after drying.

Restoration of historical buildings requires an application of suitable and convenient materials which are compatible with historical legacy. On the other hand, the used materials have to show adequate durability and fulfil current tendencies of environmental-friendliness policy. Most historical buildings have their facades made of lime-based, or more precisely, blended-lime-based plasters. Metakaolin belongs to one of the most common representatives of pozzolanic admixtures used in this field. It is an artificial product, which arises by the calcination of kaolinitic clay or claystone at temperatures of about 550–900 °C. Like every other production process, a remarkable amount of waste rises also in the case of metakaolin. This study is aimed at the utilization of this waste, specifically the waste calcined shale (WCS). It is composed of not properly burned particles with varying compositions. Contrary to metakaolin, it contains a lower amount of amorphous phase and a higher amount of kaolinite and mullite. WCS was used in the production of lime-based plasters with a dosage of up to 50%. During the hardening, the carbonation process takes place in combination with the pozzolanic reactions. It gives rise to a higher amount of amorphous structures, about 15% in the case of pure lime contrary to up to 45% (in the highest dosage of WCS) and other crystal phases such as calcium-aluminate-carbonate hydrates. Obtained phase analyses are supported by the determination of SEM analysis and mechanical properties, which are also measured depending on time.

The thermal and acoustic properties of innovative insulating systems used as building coatings were investigated: Granular silica aerogel was mixed with natural plaster in different percentages. This coating solution is transpiring and insulating, thanks to the use of a natural lime coat and aerogel, a highly porous light material with very low thermal conductivity. The thermal conductivity of the proposed solution was evaluated by means of a Heat Flow meter apparatus (EN ISO 12667), considering different percentages of aerogel. The natural plaster without aerogel has a thermal conductivity of about 0.50 W/m K; considering a percentage of granular aerogel of about 90% in volume, the thermal conductivity of the insulating natural coating falls to 0.050 W/m K. Increasing the percentage of granular aerogel, a value of about 0.018–0.020 W/m K can be reached. The acoustic properties were also evaluated in terms of the acoustic absorption coefficient, measured by means of a Kundt’s Tube (ISO 10534-2). Two samples composed by a plasterboard support, an insulation plaster with aerogel (thicknesses 10 mm and 30 mm respectively) and a final coat were assembled. The results showed that the absorption coefficient strongly depends on the final coat, so the aerogel-based plaster layer moderately influences the final value. The application of this innovative solution can be a useful tool for new buildings, but also for the refurbishment of existing ones. This material is in development: until now, the best value of the thermal conductivity obtained from manufacturers is about 0.015 W/m K.

The phase field method is a versatile simulation framework for studying initiation and propagation of complex crack networks without dependence to the finite element mesh. In this paper, we discuss the influence of parameters in the method and provide experimental validations of crack initiation and propagation in plaster specimens. More specifically, we show by theoretical and experimental analyses that the regularization length should be interpreted as a material parameter, and identified experimentally as it. Qualitative and quantitative comparisons between numerical predictions and experimental data are provided. We show that the phase field method can predict accurately crack initiation and propagation in plaster specimens in compression with respect to experiments, when the material parameters, including the characteristic length are identified by other simple experimental tests.

Instead of using paint, it is possible to manufacture white paper plaster by adding chalk to its ingredients. The moisture buffer values (MBVs) of paper plaster mixtures with chalk ranged from 1.8 to 2.9. The higher the chalk content was, the lower the MBV of the paper plaster was. Only the mix with the highest chalk content, where the percentage of chalk was 90, had a moisture buffering capacity below 2.0, i.e., not excellent (MBV > 2.0).

The appropriate selection of renovation plaster properties is essential for ensuring the durability and effectiveness of conservation works. This study focused on the design and characterization of cement-based renovation mortars modified with synthetic zeolites with different Si/Al ratios. It was assumed that high-silica zeolites would provide more favorable mechanical and hygric performance than low-silica types. Owing to their porous structure and pozzolanic reactivity, zeolites proved to be effective additives, enhancing both the microstructure and functionality of the mortars. The modified mixtures exhibited increased total porosity, higher capillary absorption, and improved moisture transport compared with the reference mortar based on CEM I 52.5R. Dynamic vapor sorption tests confirmed that the zeolite-containing mortars achieved Moisture Buffer Values (MBV) above 2.0 g/m2, which corresponds to the “excellent” moisture buffering class. Electrical resistivity measurements further demonstrated the relationship between denser microstructure and enhanced durability. At the frequency of 10 kHz, the electrical resistivity of the reference mortar reached 43,858 Ω·m, while mortars with 15% ZSM-5 and 15% Na-A achieved 62,110 Ω·m and 21,737 Ω·m. These results show that the addition of high-silica zeolite promotes the formation of a denser and more insulating matrix, highlighting the potential of this method for non-destructive quality assessment. The best overall performance was observed in mortars containing the high-silica zeolite ZSM-5. A 35% replacement of cement with ZSM-5 increased compressive strength by 10.5% compared with the reference mortar R (4.3 MPa). Frost resistance tests showed minimal mass loss (0.03% at 15% and 1.79% at 35% replacement), and ZSM-5 mortars also maintained integrity under salt crystallization. These improvements were attributed to the reaction of reactive SiO2 and Al2O3 from the zeolites with Ca(OH)2, leading to the formation of additional C-S-H. A higher Si/Al ratio promoted a denser, fibrous C-S-H morphology, as confirmed by SEM, which explains the improved strength and durability of mortars modified with ZSM-5.

The objective of this study was to determine mould resistance of the plaster made from waste paper. To study the plaster quality, two laboratory tests were conducted. First, mould resistance of a dry plaster was studied, and second, mould resistance of a wet plaster was tested. Since wet plaster mix must be used for plastering, the resulting surfaces are extremely wet. The plaster placed on the wall would dry for at least two weeks under favourable conditions (sufficient ventilation and temperature). During this period, there is a great risk that the plaster might become mouldy. Another risk of becoming mouldy occurs when an already plastered wall receives moisture (e.g., water damage). The experiments carried out under laboratory conditions showed that in an environment with high relative humidity the plaster did not become mouldy.

This work explores the application of Allium sativum (Garlic) extract, in the creation of novel polymeric core‐sheath fibers for wound therapy applications. The core‐sheath pressurized gyration (CS PG) technology is utilized to mass‐produce fibers with a polycaprolactone (PCL) core and a polyethylene oxide (PEO) sheath, loaded with garlic extract. The produced fibers maintain structural integrity, long‐term stability and provide a cell‐friendly surface with rapid antibacterial activity. The physical properties, morphology, therapeutic delivery, cytotoxicity, thermal and chemical stability of PCL, PEO, PEO/Garlic, Core‐Sheath (CS) PEO/PCL and PEO/Garlic/PCL fibers are analyzed. Findings show that the addition of garlic extract greatly increases the fibers’ thermal durability, while decreasing their diameter, thus improving cell adhesion and proliferation. In‐vitro release tests reveal a rapid release of garlic extract, which has significant antibacterial action against both Gram‐negative Escherichia coli (E. coli) and Gram‐positive Staphylococcus aureus (S. aureus) bacteria species. Cell viability experiments validate the fiber samples' biocompatibility and nontoxicity, making them appropriate for integrative medicine applications. These core‐sheath structures emphasize the potential of combining natural therapeutic agents with advanced material technologies to develop cost‐effective, sustainable and highly effective wound dressings, offering a promising solution to the growing concerns associated with conventional synthetic antibacterial agents. Core‐sheath structures, consisting of a polycaprolactone (PCL) core and a polyethylene oxide (PEO) sheath loaded with garlic extract, are mass‐produced using the pressurized gyration technique. These fibers proven to have significant antimicrobial efficacy and high cell viability, making them desirable for wound healing applications. This approach overcomes limitations associated with the use of synthetic antibacterial agents and fiber manufacturing techniques.