Ramune Zurauskiene

This study investigates the reaction of charred wood cladding systems to fire, focusing on the influence of wood species, charred surface treatment, flame retardant treatment, surface coating and board orientation. Nine different configurations of larch and spruce cladding samples with 20 mm thickness were investigated, which were installed into the system according to standard requirements. The samples differed by wood type, charred surface treatment, board orientation, covering with flame retardant agents and additional surface coverings. Two commercial flame retardant treatments and three commercial surface coatings were included in the experimental matrix. Fire behaviour was evaluated according to the EN 13823 Single Burning Item (SBI) method, analysing the ignition time, fire growth rate index, total heat release from the specimen in the first 600 s of exposure to the main burner flames, smoke growth rate index and total smoke production from the specimen in the first 600 s of exposure to the main burner flames as indicators. Although it was determined that the ignition time fluctuated in a relatively narrow range (from 5 min 12 s to 5 min 36 s), analyses of the additional SBI indicators revealed much clearer differences between the systems. The best results were obtained for the charred notched spruce system treated with the phosphate-, urea- and biocide-based flame retardant, which had the longest ignition time and lowest values for the investigated indicators. Meanwhile, the least favourable behaviour was observed in the notched untreated spruce system and in the horizontally oriented system, marked by higher fire spreading and smoke formation values. The obtained results show that the reaction of a wood cladding system to fire is not determined only by the type or application rate of flame retardant, but also the whole system’s structure, including the wood type, surface processing, covering combination and installation configuration.

Nature-based solutions, including green infrastructure (GI), are considered sustainable tools for stormwater treatment. GI elements (rain gardens, green roofs, etc.) are increasingly applied as integrated approaches for climate change mitigation and environmental pollution reduction. This study focused on investigations of rain gardens for reducing stormwater polluted by residual chlorine after the disinfection of outdoor spaces. Laboratory (column test) and field tests were carried out to evaluate the infiltration capacities of an experimental rain garden model, as well as its efficiency for retaining residual chlorine. The experiments were conducted using simulated rain garden layers composed of waste materials that remained after different production processes. The average infiltration coefficient values obtained were 2.55 × 10⁻⁵ m/s, 2.45 × 10⁻⁵ m/s, 2.24 × 10⁻⁵ m/s, 3.4 × 10⁻⁵ m/s, 1.28 × 10⁻⁵ m/s, 1.84 × 10⁻⁵ m/s (laboratory test), and 1.39 × 10⁻⁵ m/s (field test). These values correspond to the characteristics of sand–gravel substrates. A chlorine retention efficiency of 82.5–87% was obtained. Granulometric analysis confirmed fraction size suitability for rain garden filtration. This research indicates the potential of rain gardens for reducing stormwater pollution, providing a basis for future research and practical implementation.

Various methods for classifying and evaluating the shape, size, and surface texture of sand particles are examined, highlighting their impact on concrete mixture properties. This study emphasizes the role of particle morphology in determining concrete workability and segregation, particularly in glass-fiber-reinforced (GRC) thin-layer concrete for building facade panels. The effects of different aggregate types on concrete workability and segregation are analyzed, showing that aggregates with spherical particles and a lower elongation index improve mixture consistency and reduce segregation. Three types of fine aggregates were used (instead of quartz sand in the mixtures, natural sand and granite screenings were chosen, which would be a sustainable alternative to quartz sand), and thin-layer glass-fiber-reinforced concrete using aggregates of different shapes was characterized by layering the mixture. The workability and segregation of fine-grained fiberglass-reinforced concrete mixtures depend on the aggregate particles’ shape. Up to 50% of quartz sand can be replaced with granite siftings or natural sand, as measured by the segregation index, as calculated according to the method proposed in this paper. Increasing the amount of natural sand from 10% to 50% also increases the segregation index from 1.9 to 2.6, and when using granite sifting aggregates, it rises from 2.6 to 3.5. Aggregates with spherical particles are more suitable for this thin-layer GRC concrete, if we examine the consistency parameters of fresh concrete and the possibilities of working with it in real production conditions.

Various methods for classifying and evaluating the shape, size, and surface texture of sand particles are examined, highlighting their importance in concrete mixture properties. The study emphasizes the role of particle morphology in determining concrete workability and segregation, particularly in glass fiber reinforced (GRC) thin-layer concrete for building facade panels. The effects of different aggregate types on concrete workability and segregation are analyzed, showing that aggregates with spherical particles and a lower elongation index improve mixture consistency and reduce segregation. Three types of fine aggregates were used for the research. Thin-layer concrete dispersively reinforced with concrete fiberglass using aggregates of different shapes is characterized by a layering of the mixture. The workability and segregation of the fine-grained fiberglass-reinforced concrete mixture depend on the shape of the aggregate particles. Up to 50% of the quartz sand can be replaced with granit stiftings or natural sand, as measured by the segregation index. Increasing the amount of natural sand from 10% to 50% also increases the segregation index from 1.9 to 2.6, and when using granite stiftings aggregates from 2.6 to 3.5, respectively. The segregation index can be calculated according to the method proposed in this paper. Aggregates with spherical particles are more suitable for this thin-layer GRC concrete.

Recyclable construction waste can be used as a low-cost material to reduce stormwater pollution caused by various pollutants. In recent years, studies have reported increased water contamination from chlorine and chlorine compounds and its negative impact on aquatic ecosystems. When assessing the need for waste recycling, circularity, and stormwater reuse, it is worth evaluating the capacities of construction waste materials to reduce stormwater pollution from residual chlorine. Laboratory experiments using bentonite waste material (bentonite clay) and sodium hypochlorite solutions were carried out to analyze the potential of bentonite clay to retain residual chlorine in stormwater and evaluate its capacity to be applied as filtration media in green infrastructure. In the first stage, the particle size distribution and texture of bentonite clay were assessed using laboratory sieve analysis and microscopy. The results of the experiments indicated that the optimal grain size to retain pollutants was 0.8–2.0 mm. The microstructure analysis showed the capacity of bentonite to retain residual chlorine. The results of the static and dynamic experiments (leaching and filtration tests) show that the bentonite clay retained up to 44% of the residual chlorine. The obtained results indicate that bentonite clay might be suitable for application as filtration media in green infrastructure to reduce stormwater contamination.

In recent decades, the pollution of water with micropollutants has become an increasing environmental concern. Since 2019, increased stormwater pollution from chlorine-based disinfectants has been recorded due to the COVID-19 pandemic. Runoff from disinfected areas and the residual chlorine present in stormwater are transported to surface water bodies, posing a risk to aquatic flora and fauna. The objectives of this study were (1) to evaluate the efficiency of different low-cost and recyclable filter materials in removing residual chlorine, and (2) to test plants’ ability to reduce residual chlorine concentrations through phytoremediation. Experiments were conducted in the laboratory (column and batch) and in the field (raised garden bed) to assess the efficiency of various filter materials (peat, wood chips, sawdust and the lightweight aggregates) in retaining residual chlorine to be implemented in green infrastructure. The best retainers of chlorine were sawdust (96%) and the LWA Leca (76%). No harmful effects of residual chlorine (changes in growth, color, leaf size, etc.) on plants (Tagetes patula or Pisum savitum) were observed and the residual chlorine in the leachate samples was below the equipment’s detection limit. Our research results will contribute to future studies aiming to remove various micropollutants from stormwater using remediation technologies.

In recent decade water pollution by micropollutants is an increasing environmental concern. Since 2019, due to COVID-19 pandemic, increased stormwater pollution by chlorine based disinfectants has been determined. Research aimed to treat of chlorine contaminated stormwater after outdoors spaces disinfection are very limited. Runoff from disinfected areas and residual chlorine present in stormwater are transported to surface water bodies. Residual chlorine reacts with dissolved organic compounds in water and results the formation of environmentally toxic disinfection by-products. Studies present event low residual chlorine concentrations may pose a risk to aquatic flora and fauna. In this study the efficiency of different filter materials, including peat, wood chips, sawdust (column tests) and ceramzites Leca, Pollytag, Polski, Ceski (batch tests), in retaining residual chlorine were tested in laboratory scale batch and flow through experiment. The best efficiency to retain chlorine presented sawdust (96 %) and ceramzite Leca (76 %). The plants abilities to reduce pollution by chlorine was analyzed in raised garden bed. Research results will contribute to future studies aimed to retain various micropollutants in stormwater using remediation technologies.

In case of a fire, the flame can spread from the building through the outer openings to the outside. In such cases, the fire temperature thermal effect determines the façade fibrocement tile thermal destruction, while the flammable thermo-insulating systems used for building energy effectiveness ensures it sets on fire. The spread of such a fire becomes uncontrollable and raises an immediate danger to the people inside the building, while such event dynamics delay and make it harder to put out the fire. Extra additive usage in façade fibrocement tiles can raise its resistance to fire temperature effect. Carbon fiber is widely known as a material resistant to the high temperature destructive effect. An investigation was conducted on the influence that carbon fiber has on the properties of autoclaved fiber cement samples. The autoclaved fiber cement samples were made from the raw materials, typical for façade fiber cement plates, produced in an industrial way (using the same proportions). In the samples, carbon fiber was used instead of mix cellulose fiber in 0.5%, 0.75%, 1% proportions. After completing the density research, it was determined that the carbon fiber effect had no general effect on the sample density. Ultrasound speed spreading research showed that the carbon fiber insignificantly makes sample structure denser; however, after the fire temperature effect, sample structure is less dense when using carbon fiber. The results of both these investigations could be within the margin of error. Insignificant sample structure density rise was confirmed with water absorption research, which during the 1% carbon fiber usage case was lower by 4.3%. It was found that up to 1% carbon fiber usage instead of mix cellulose fiber creates a dense structure of autoclaved fiber cement samples, and the carbon fiber in the microstructure influences the mechanical properties of the autoclaved fiber cement samples. After using carbon fiber in ambient temperature, the sample compressive strength and bending strength increased. However, the results of mechanical properties were completely different after experiencing fire temperature effect. Scanning electron microscopy research showed that the bond between the carbon fiber and the cement matrix was not resistant to high temperature effect, due to which the structure of the samples with carbon fiber weakened. Research showed that carbon fiber lowers the mechanical properties of the autoclaved fiber cement samples after high temperature effect. After analyzing the density, ultrasound speed spreading, water absorption, microstructure and macrostructure, compressive strength, and bending strength, the authors determined the main CF usage for AFK dependencies: 1. CF usage up to 1% replacing MCF makes the AFK structure more dense up to 1.5%, and lowers the water absorption up to 4.3%; 2. CF incorporates itself densely into the AFC microstructure; 3. CF usage up to replacing MCF improves the AFK strength properties up to until the fire temperature effect. Compression strength increases up 7.3% while bending strength increases up to 14.9%. 4. AFK hydrate amount on CF surface is lower than on MCF; 5. Fire temperature effect on AFK with CF causes dehydration by removing water vapor from the microstructure, resulting in a lot of microcracks due to stress; 6. The CF and cement matrix contact zone is not resistant to fire temperature effect. SEM experiments were used to determine the CF “self-removing” effect; 7. Due to complex changes happening in the AFK during fire temperature effect, CF usage does not improve strength properties in the microstructure. Compression strength decreases to 66.7% while bending strength decreases to 20% when compared with E samples.

In the last few years, ceramic tiles and tiles from natural rock with higher measurements were used. A huge amount of tile glue is used for high-measurement tile gluing due to a special gluing technology, which is characterized by a thicker glue layer. Due to this, a higher and higher amount of tile glue is used up during decorating. Regular tile glue mixture uses up to about 50–60% cement (according to mixture mass). In carried-out experiments, a lower amount of cement was used in tile glue mixture production (30%). Additionally, 5%, 10%, 15%, 20% and 25% of sand was replaced with small foam glass granules. These granules are made from glass waste. By using foam glass granules, lighter tile glue mixtures were produced, while reducing the cement amount can lower energy usage and CO₂ emissions into the atmosphere. The main properties of tile glue were investigated as follows: flow of mixture, density, compressive strength, bending strength, tensile-adhesive strength, slip and water absorption. The properties obtained during the research prove that newly produced tile glue mixtures fulfill all requirements given to these types of mixtures. A total of 25% of foam glass granule from filler mass can be used in tile glue production.

Pollution caused by the use of disinfectants in public spaces is a relatively new form of environmental contamination. During the COVID-19 pandemic of 2020–2021, early research showed a sevenfold increase in the use of disinfectants to clean outdoor spaces and a corresponding increase in environmental pollution. Typically, after entering stormwater systems, disinfectants are carried to surface waters (e.g., rivers, seas and lakes) where they react with various elements to form harmful compounds. In the absence of data, it is not possible to determine accurate levels of pollution according to the latest scientific information. Our enquiry demonstrates that stormwater pollution indicators (pH, conductivity, turbidity and color intensity) change depending on the amounts of disinfectants present. Laboratory tests were conducted using hemp fiber and ceramzite, in which filtered stormwater samples contaminated with different amounts of disinfectants showed decreases in the amounts of active chlorine from 2.93 ppm to 1.0 ppm. Changes in pH levels, conductivity, turbidity and color intensity were monitored before and after filtration; pH indicators changed slightly (from 7.81 to 7.85), turbidity changes varied in the range of 0.070–0.145 NTU and the highest value of color intensity (1.932 AV) was obtained when 50 mL of disinfectant was added to the investigated sample water. This article presents the results of our research into the impact of disinfectants on stormwater. Further investigation is needed in order to determine the impacts of chemical substances on our water ecosystem.