Microwave radiation and its application on construction materials

Drying structures using high-frequency electromagnetic radiation or microwave technology is currently gaining much more usage in the engineering practice. The goal of the method is the quickest elimination of water in construction (wall, floor structure, etc.). Microwave is a part of the electromagnetic radiation of frequency between 300 MHz and 300 GHz and wavelength between 1 mm and 1 m. The frequency of 2.45 GHz and 122 mm wavelength is used for engineering practice. Due to the effect of microwave radiation the divergent homogeneity of temperature field of different building materials can be observed. This article discusses the spread of thermal field depending on the volume of water and thereby the size of mass humidity of the given material (timber). The temperature fields will be observed by a thermo camera, always after a certain time cycles of the heating

Effect of Microwave Radiation on the Compressive Strength of Solid Ceramic Brick

Microwave radiation is widely utilized in construction practice, especially for drying building materials, remediating damp masonry, or sterilization of biotic pests that have infested building structures. The available scientific and technical literature reports that certain materials exposed to microwave radiation do not change their physical and mechanical properties, although this has not yet been adequately verified. This paper builds on many years of research in the area, adding to and refining existing information, providing new insights into the mechanical and physical properties of commonly available building materials that have been exposed to controlled microwave radiation, and comparing them with reference values. The experimental research on a set of clay brick samples is carried out using tests according to European standards, and it focuses on the effect of microwave radiation on compressive strength and water absorption. The experimental samples were compared to reference samples that had not been subjected to prolonged exposure to moisture and were subsequently treated with microwave radiation for dehumidification

Comparative Assessment of the Impact of Electricity Consumption in Different Economic Sectors on the Economic Development of the EU Member States

Recently, the Member States of the European Union (EU) have found themselves in a controversial situation. On the one hand, national economic development is barely possible without increasing electricity consumption, whereas on the other we are facing increased use of natural resources (coal, oil, gas, wood), thermal effects, pollution and risks to human health. The European Green Deal is a response to the currently observed negative trends. The strategy aims to accelerate the economic development of the EU Member States, thus reducing electricity consumption. Objectives may include both the national economy and the electricity generation sector by applying advanced technologies and introducing innovations that increase output efficiency while reducing electricity costs. Assessing the current situation is vital for the successful implementation of the European Green Deal, i.e., by comparing the impact of electricity consumption on the economic development of the Member States. Thus, combining indicators for national economic development and the extent of electricity consumption into a single aggregate is necessary because electricity greatly affects economic development. The proposed methodology allows dividing the analysed EU Member States into three groups, in line with the degree of national economic development and the scope of electricity consumption in their economy sectors

Measurement of the runoff coefficient of extensive greenroof

Describes the procedure of experimental measurement of the runoff coefficient C, both of individual layers and the entire composition extensive green roofs. Experimental measurements make it possible to determine the reference behaviour of runoff characteristics, namely runoff coefficient C, with emphasis on the simulation of the real behaviour of extensive green roofs. The aim is an elementary description of the structural and physical behaviour of extensive green roofs. For the needs of experimental measurement, the dimensional and shape limits of test specimens are described, the conditions for conditioning of individual specimens, the boundary conditions of execution and individual steps of the experiment. Then is specified the method of evaluation and subsequent verification of measured data. The result of the experimental measurement is the amount of drained water from the tested specimens of the extensive green roof at time t, which shows a nonlinear behaviour. From the set of measured data, it is then possible to predict the behaviour of extensive green roofs in real conditions and to determine the runoff coefficient C of the tested specimens. These data represent reference values for the subsequent design of sub-elements and structures of buildings

Experimental Fire Resistance Test of Timber Structure

Wooden materials have many advantages for their use in buildings. There are many limitations for their use as with other materials. It's because of the mechanical-physical properties of natural wood. With the use of the wooden structure of the building, the fire load is increased and the requirements for the fire safety solution are stricter. The combustible load-bearing structure influences the design of the building in terms of its function, layout solution, structural materials, and fire safety equipment. The data of the behaviour of wooden materials in the event of fire are necessary for the correct design a timber structure with the required fire resistance. This paper is focused on experimental testing of timber structures exposed to extreme situations such as the effects of fire

Polyurethane adhesives in flat roofs

It is necessary to stabilize individual layers of flat roofs, mainly because of wind suction. Apart from anchoring and surcharge, these layers can be secured by bonding. At present gluing is an indispensable and widely used stabilization method. On our market we can found many types of adhesives, most widely used are based on polyurethane. This paper focuses on problematic about stabilization thermal insulation from expanded polystyrene to vapor barrier from bitumen. One of the main issues is to calculate the exact amount of adhesive, which is required to guarantee the resistance against wind suction. In this problematic we can not find help neither in technical data sheets provided by the manufactures. Some of these data sheets contain at least information about amount of adhesive depending on location in roof plane and building height, but they do not specify the strength of such connection. It was therefore resorted to select several representatives polyurethane adhesives and their subsequent testing on specimens simulating the flat roof segment. The paper described the test methodology and results for two types of polyurethane adhesives