The stabilized waste dust as a constituent modifying properties of wood-cement composites

Tomáš MELICHAR, Silvestr VASAS, Šárka KEPRDOVÁ, Jiří BYDŽOVSKÝ, Pavel SCHMID, Iveta HÁJKOVÁ
Brno University of Technology, Faculty of Civil Engineering, Veveří 331/95, 602 00 Brno, Czech Republic, e-mail: Tomas.Melichar@vut.cz

The research presented in this paper deals with the effect of stabilized waste dust (from cement-bonded particleboard processing) on the properties of wood-cement composites. The attention was paid to sorption characteristics and mechanical properties. The goal of the research presented was to study the properties and behaviour of wood-cement composites containing an alternative raw material once stabilised. To evaluate this aspect, composites of modified composition (filler and matrix - based on Portland and mixed cement, substitution with waste dust) were exposed to variable relative humidity ranging from 0 to 96% (increase/decrease in 10% increments). Specimens were always exposed to a given humidity (0, 10, 20, etc.) for a period of time sufficient to stabilize their weight. Absorption and then desorption took place. After the exposure to moisture was completed, the bending strength and modulus of elasticity in bending, tensile strength perpendicular to the plane of the board were tested. In this way, the effect of stabilization of spruce chips in terms of the different matrix composition of the materials was indirectly analyzed in a partial way. Sorption isotherms demonstrate the different behaviour of the materials during varying ambient air humidity. The composition of the wood-cement composites affecting the stabilization of the spruce chips (contained in the composites), among others. In case of the physical and mechanical properties a slight increase was observed.

Key words: Stabilization; Waste; Dust; Wood; Cement; Material; Substitution; Properties; Sorption; Isotherm; Modification

Waste utilization and durability of cementitious composites (in Slovak)

Adriana ESTOKOVA, Miriama CAMBAL HOLOSOVA, Martin JAS, Alena SICAKOVA
Technical university of Kosice, Faculty of Civil Engineering, Vysokoškolská 4, 04200 Košice, Slovak Republic,, e-mail: adriana.estokova@tuke.sk

The focus of the research presented is on the use of specific waste materials as supplementary cementitious components in cement-based construction materials. The primary objective is to investigate whether the incorporation of non-traditional wastes with pozzolanic properties can result in positive changes in the quality and technological parameters of cementitious composites. Cement mortars were prepared with 20% cement substitution by the mentioned wastes and subsequently compared with reference composites without any waste substitution. Several technological parameters were considered in the analysis, including compressive and tensile strength, bulk density, water absorption and consistency. Particular emphasis was placed on durability parameters, as evidenced by the measurement of aggressive ion penetration. The experimental results showed that the composites with eggshell exhibited satisfactory values in both engineering and durability parameters studied. Composites containing blast-furnace slag showed improved resistance to the penetration of aggressive ions, as expected.

Keywords: concrete, cement substitution, corrosion, industrial waste

Optimizing properties of gypsum mixtures through modifications of construction gypsum board waste (in Czech)

Hana SEKAVOVÁ, Zdeněk PROŠEK, Pavel TESÁREK
Czech Technical University in Prague, Faculty of Civil Engineering, Thákurova 7, 166 29 Prague 6, Czech Republic

The article presents the results of utilizing modified gypsum board waste from construction and demolition debris, obtained from a real construction site and processed using a developed recycling line for construction gypsum board. The research focused on examining the impact of modification (in terms of grinding fineness) on the resulting properties of dry gypsum mixtures, with replacements in the mixture ranging from 10%, 25%, to 50% by weight for gypsum binder. Parameters such as bulk density, flexural strength, and compressive strength after 7 days from the sample production were monitored. The results indicate that, with appropriate modification, it is possible to efficiently substitute a portion of gypsum binder in dry gypsum mixtures with modified gypsum board recyclate.

Keywords: recycling, construction and demolition waste, gypsum, gypsum board.

Reducing the carbon footprint of temporary site structures

Štefan KRIŠTOFIČ, Naďa ANTOŠOVÁ, Peter MAKÝŠ
Slovak University of Technology in Bratislava, Faculty of Civil Engineering, Radlinského 11, 810 05 Bratislava, Slovak Republic, e-mail: stefan.kristofic@stuba.sk

The paper focuses on minimizing the carbon footprint associated with temporary buildings on site through the identification and implementation of sustainable measures. Experimental work on two of the sites studied revealed high levels of night-time heating consumption in temporary buildings, highlighting the need for more efficient heating and insulation technologies. The analysis of the consumption showed significant opportunities for energy savings, with critical areas identified that allow for the implementation of improvements in energy management, with a potential positive impact on the overall sustainability of the construction industry.

Keywords: Carbon footprint, energy consumption, temporary buildings, construction traffic.

Agricultural production, sustainable food system and food (non)waste

Jarmila VIDOVÁ
University of Economics Bratislava, Department of Economic Policy, Dolnozemská cesta 1, 854 01 Bratislava, Slovak Republic, e-mail: jarmila.vidova@euba.sk

Agriculture is the most important branch of the economy. It is influenced by natural processes, but also by human intervention in nature, especially rapid urbanization. Another factor is globalization, population growth and pressure on the growth of food supply chains. The production of an ever-increasing amount of food to satisfy the basic needs of 8 billion inhabitants had and still has an impact on the intensification of agricultural production. Increased food production has not avoided an increase in the use of pesticides which has had an impact on soil resources, soil biodiversity and in an unplanned way on our diet. The increase in production also ensured better affordability of food. Intensive agriculture exerts significant pressure on the landscape and soil for example in the form of contamination, erosion and compaction caused by heavy agricultural machinery. It accounts for up to six percent of CO2 emissions in the entire Union. Experts draw attention to the fact that the area of land that is used worldwide to grow unnecessary food is greater than the area of India and Canada. It is necessary to seriously deal with the way crops are grown, their subsequent processing and distribution. There are several opinions on how to deal with this problem. Disruption of supply chains and restriction of transport significantly contributed to the immediate need to change some methods of production and distribution of crops and food. A particularly important topic is the relationship to the soil, food quality, food habits and waste production. Food waste is an ecological and climate product. In the European Union, almost 57 million tons of food is wasted annually, which is 127 kilograms per person. In Slovakia around 860,000 tons of food is thrown away per year, which is approximately 163 kilograms per inhabitant. The European Union is also trying to reduce the volume of food waste by fulfilling goals of the strategy "Farm-to-Fork". The European Commission is revising the waste directive to reduce food waste. In the contribution on the one hand, we focused on agriculture and its impact on the environment and its role in meeting the demand for food, and on the other hand we conducted a survey through a questionnaire. Based on our survey we can conclude that more than half of the respondents are concerned with the impact of the food they buy on the environment, some plan to limit the consumption of meat and meat products, which is a prerequisite for possible changes in consumer behaviour in relation to the environment, primarily to minimize waste with food.

Keywords: affordability of food, the environmental footprint, food safety, food waste.

Sustainable school meals: application of circular principles in Czech school canteens (survey 2023) (in Czech)

Matěj LUKSCH and Hana DOLEŽALOVÁ
University of South Bohemia in České Budějovice, Faculty of Economics, Studentská 13, 370 05 České Budějovice, Czech Republic, e-mail dolezal@ef.jcu.cz, lukscm01@ef.jcu.cz

School meals should serve, in particular, to provide tasty, healthy food and to promote good eating habits. At the same time, however, it can have a significant positive effect on the environment and the community after the introduction of circular principles; the system serves around 2 million diners every day in the Czech Republic alone.  The purpose of the survey carried out as part of the Grant Project of the University of South Bohemia GAJU 103/2023/S was to analyse how these principles are integrated into the day-to-day operation of school canteens. The online questionnaire gradually addressed the level of awareness of school canteen management about the very concept of sustainable gastronomy, the assessment of its importance within the school environment and the extent of application of selected circular principles. Attention has also been paid to communicating the sustainability of school meals with all stakeholders and educating staff. The approach of school canteens to considered changes to the school meals system has been monitored, and space has also been left for the presentation of their own proposals and comments.

The main challenges for Czech school meals include: opening up opportunities for local farms and businesses; using high-quality, organic raw materials as possible; respecting seasonality; greater variety and higher sensory value of prepared dishes; optimising delivery; reducing food waste; efficient waste management, especially gastro-waste; improving information of sustainable aspects of eating and strengthening mutual communication.

Keywords: School canteens, sustainable school meals, principles of circular gastronomy, changes to school meals.

Autorská práva:

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Autorská práva:

WASTE FORUM, jejímž autorem je CEMC - České ekologické manažerské centrum, podléhá licenci Creative Commons 3.0 Česko. V případě převzetí článku vždy uvádějte WASTE FORUM jako zdroj s prolinkem, děkujeme.

WASTE FORUM, authored by CEMC - Czech Environmental Management Center, is licensed under a Creative Commons Attribution-Noncommercial 3.0 Czechia license. When taking over the article, always mention WASTE FORUM as a source with a link, thank you.

ISSN: 1804-0195