Ústav technologie stavebních hmot a dílců

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Utilization of alternative wood particles for modern thermal insulation products
(IOP PUBLISHING LTD, 2024-05-13) Zach, Jiří; Peterková, Jitka; Novák, Vítězslav; Korjenic, Azra
Thermal insulation materials play a vital role in minimising energy loss in building operation and also affect the amount of greenhouse gas emissions associated with heating and cooling. In this context, it is becoming an increasingly important milestone to find suitable thermal insulation materials that not only meet the technical requirements but also minimise their environmental impact. The trend towards the use of eco-friendly materials for thermal insulation reflects the construction industry's desire to contribute to environmental protection and the transition to more sustainable models of building construction and renovation. For more than 20 years, a number of research teams have been investigating the possibility of replacing synthetically produced materials such as mineral wool and polystyrene foam with natural fibre-based insulation materials. These alternatives include wood as a traditional, easily renewable raw material. This, together with the low energy intensity of processing and manufacturing wood materials, contributes to its low carbon footprint. Compared to traditional synthetic insulation materials, which are often energy intensive to produce, wood is a more environmentally friendly choice. However, with many European countries now facing a potential shortage of higher quality wood, it is necessary to look for alternative sources of wood, including in the field of thermal insulation materials, materials with a lower carbon footprint that can be produced from lower quality wood or from wood waste that would otherwise only have an energy use. The paper is devoted to the study and use of suitable wood waste and secondary raw materials from spruce wood (coarse wood chips, sawdust and wood flour) for the development of modern thermal insulations with the aim of an environmentally friendly and less energy-intensive production process compared to conventional insulants.
Characteristics of Fibres Based on Secondary Raw Materials and Their Use in Concrete Technology
(Czech Technical University in Prague, 2024-05-18) Sedlmajer, Martin; Bubeník, Jan; Zach, Jiří; Novák, Vítězslav
Different types of fibres in cementitious composites, particularly in concrete, are currently used for a number of reasons. Fibres are being added to improve mechanical properties (especially steel and glass fibres), to increase the durability – to reduce occurrence of microcracks during the concrete aging (mainly synthetic and cellulose fibres), or to increase the fire resistance (polypropylene fibres). Within the study, characterization of different types of alternative fibres (fibres generated during waste recycling that would otherwise end in incinerators or landfills) with possible use in cementitious composites. These were fibres from recycled PET bottles, paper, and mineral wool, whose properties were compared to the traditionally used cellulose and polypropylene fibres. In the experimental part, the thickness, length, shape, and surface of individual fibres were monitored by an optical microscope. Furthermore, the amount of heat of combustion was determined by the calorimetric method, and the differential thermal analysis (DTA) was carried out for determination of the impact of high temperature on monitored fibres. The microstructure of fibres was monitored using a scanning electron microscope. The focus of the experimental study was on fibres usable in concrete and capable of enduring high temperature stress.
Utilization of Fluidized Bed Combustion Fly Ash in the Design of Reuse Clay Soil in the Form of Self-Compacting Grouts
(MDPI, 2020-04-23) Drochytka, Rostislav; Michalčíková, Magdaléna
This paper addresses the influence of fluidized bed combustion fly ash (FBCA) and further liquefying additives on the formation of structure and on the resulting properties of self-compacting grouts based on clay soil. In order to give the best account of the influence of individual input materials, tests were conducted on samples without the use of fluidized bed combustion fly ash. Clay soil (Cl) and cement were used as input materials, and fluidized bed combustion fly ash (10% and 30%) and a liquefying additive (sodium carbonate 0.1%) were used as an admixture. It has been experimentally determined that the use of 10% FBCA with clay soil is most suitable for achieving the optimal spillage parameter of self-compacting grout (class SF2 (660–750 mm) and class SF3 (760–850 mm)). It was also found that fluidized bed combustion fly ash and the liquefying additive have a significant influence on the formation of the structure of the self-compacting grout and, due to their presence, the compressive strength of the samples increased up to 0.5 MPa after seven days of hardening. The reaction between 0.1% of sodium carbonate and clay soil increased the electrokinetic potential, which reduced the viscosity of the self-compacting grout. Within the research work, the verification of the developed self-compacting grout in situ was also carried out.
The influence of green walls on interior climate conditions and human health
(EDP Sciences, 2019-09-02) Peterková, Jitka; Michalčíková, Magdaléna; Novák, Vítězslav; Slávik, Richard; Zach, Jiří; Korjenic, Azra; Hodná, Jana; Raich, Benjamin
In recent years, many researchers have addressed the issue of interior climate and how it affects human health. Investigations performed at schools and office buildings have found that CO2 concentrations often exceed the limit value of 1500 ppm given in Decree No. 20/2012 Coll., on technical requirements for buildings. In addition, interior space often exhibits very low relative humidity. This results in poor conditions that are detrimental to human health and not conducive to studying and work. One means of improving the interior microclimate is implementing green walls. These walls can help generate a much better climate and greatly enhance the mental well-being of the inhabitants. In addition, they greatly improve dust levels and acoustics in the room. The research compared the interior conditions in two classrooms at the Faculty of Civil Engineering, Brno University of Technology. One had a green wall installed while the other was in its original configuration. CO2 concentration, temperature, and relative humidity were measured. A survey was conducted to assess the influence of the green wall on students and teachers (mental well-being, efficiency, productivity, creativity, etc.). Results obtained thus far show that the room with the green wall provides far better interior conditions, mainly in terms of lower CO2 concentration and higher relative humidity, improving students’ and teachers’ mood and health (as confirmed by the survey as well).
Chemically resistant polymeric jointing grout with environmental impact
(Elsevier, 2021-07-19) Drochytka, Rostislav; Hodul, Jakub; Mészárosová, Lenka; Jakubík, Aleš
This paper deals with the study of the chemical resistance of polymeric jointing grouts intended for thejointing of elements that are permanently stressed by an aggressive chemical environment, such as ele-ments made of cast basalt, placed in the concrete structures of sewerages. The paper researches threetypes of epoxy jointing grouts designed for conditions where there is a chemically aggressive environ-ment. The optimal amount of hazardous waste (end product and cement bypass dusts) was incorporatedin the developed jointing grouts. As part of chemical resistance monitoring, changes in selected physicaland mechanical properties of jointing grouts were monitored and evaluated, including microstructuremonitoring after chemical stress. The scanning electron microscopy (SEM) was used for the explanationof bonding effects of the polymer matrix with the filler It was found that the use of hazardous waste ishighly effective in polymeric grouts with high chemical resistance; there was no noticeable reduction inthe chemical resistance of these jointing grouts compared to the reference grouts.

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