Assessing the effect of a white Portland cement admixture on the early frost-thaw resistance of NHL-based masonry mortar

Well preserved mortars based on natural hydraulic lime are widely spread in historical buildings throughout the alpine area of Tyrol, Austria. These are frequently restored with mortars oriented on historical models. Portland cement is also commonly used to modify these materials on building sites to speed up the setting time to improve the early frost-thaw resistance, primarily when they are applied around the winter season. Therefore, it was our objective to specify the application potentials of those materials, respecting the intended use and the atmospheric conditions. Moreover, we tried to figure out the possible benefits and risks when using NHL-based materials, optionally modified by cement, yielding stable recommendations for the work with corresponding mortars. Hence, we examined the development of strength and water transport, also the frost-thaw durability in a temporal context. The obtained results were compared with findings of assessing both materials under variable weather conditions around the winter season. Accordingly, the use of pure NHL-based lime mortars resulted as being critical mainly until about two months before intense frost conditions. Cement effectively contributes to the rapid hydraulic setting reaction in NHL-based materials. Hence, we recommend measured cement additions in areas where strong frost is expected after a few weeks and especially targeted in areas where carbonation is hindered because of excess moisture. Nevertheless, the potential use of Portland cement should be properly controlled in historic building preservation. A systematical approach that considers the framework conditions and the corresponding application to an area is essential to assure an appropriate conservation outcome.

Caucasian Rhododendron Grinding-Fixing Machine

An endemic plant species typical for the Caucasus is the Caucasian rhododendron (Rhododendron caucasicum Pall), which, due to its unique chemical composition, has many medicinal properties, therefore, folk healers have used it since ancient times to treat various severe and mild diseases. At the present stage of the development of science, the question arises about the possibility of using this most valuable plant for industrial purposes. The question is raised of the production of mate tea from the Caucasian rhododendron. The rhododendron processing technologies proposed so far are reviewed and it is shown that none of them can provide aromatic and taste indicators characteristic of tea mate in the resulting product due to the fact that most of them are based on the processing technology of ordinary black tea. It is substantiated that in order to obtain mate tea, it is necessary at the initial stage of processing to fix the raw material from rhododendron, cut it and grind it to sizes acceptable for packaging, remove excess moisture contained in the sheet and give the final product a light smoke aroma and a slightly bitter taste. To solve these problems, a schematic diagram of a new machine for the simultaneous grinding and fixing of the Caucasian rhododendron is proposed.

Moisture Risk Analysis for Three Construction Variants of a Wooden Inverted Flat Roof

The paper presents an analysis of the hygrothermal performance of an inverted flat roof with a CLT (cross-laminated timber) structure in a building that meets the requirements of Passive House Standard (PHS) with regards to the potential risk of moisture. The calculations were made in the WUFI®Plus and WUFI®Bio software. The following variants were taken into account: three structure configurations, three different external climates and different scenarios of microclimate control and air change rate. The results of the calculations show that, especially in cooler climates, there is an actual moisture risk in the structure despite the excellent thermal insulation. The structure of the inverted flat roof, due to the use of a tight membrane on the outer side, allows for the partition to discharge the excess moisture only to the inside of the building. Ensuring the comfort of users may require periodic humidification of internal air, which translates directly into an increase in moisture content of the structure. The performed analysis clearly showed that there are no universal solutions. It is important to point out that for the proper performance of inverted wooden roofs, it is crucial to analyse moisture, not only thermal and energy parameters.

TRNSYS simulation of desiccant integrated hybrid cooling and dehumidification system

The traditional air conditioners suffer from performance degradation especially in humid conditions. This is due to fact that the excess moisture level in ventilation air considerably increases latent cooling load of the space to be conditioned. The use of desiccant integrated sensible cooling system can alleviate this problem by controlling the temperature and humidity separately. It also reduces energy consumption for obtaining desired thermal comfort. In the present study, TRNSYS simulation studio project has been developed to perform the simulations of the desiccant dehumidifier coupled HVAC system for different configurations in summer cooling season. Measurements are also carried out to observe the influence of operating parameters on system performance. The obtained results show that the proposed system has ensured a substantial reduction in process air humidity at dehumidifier exit while maintaining the conditioned room comfort.

Hygrothermal simulations of timber-framed walls with air leakages

Air leakages can create substantial excess moisture loads into envelope structures and degrade their hygrothermal performance. Multiple previous research projects have studied the behaviour and modelling of air leakages in building physics applications, but it is still quite rare to see air leakages being considered in practical building design simulations. The purpose of this paper is to present the selection of input parameters for air leakage simulations, utilisation of a factorial design to manage simulation cases and the results for a timber-frame wall with and without air leakages. According to the results, the air permeability of mineral wool and the air pressure difference over the envelope were the two most important factors for the dry air mass flow through the structure, as opposed to gap width and leakage route. An ideally airtight structure had a better hygrothermal performance compared to leaky structure. However, when leakages were present, the exact yearly average air flow rate in the range 70…420 dm3/(m2h) did not have a strong correlation to the performance indicators. For the other studied variables, the existence of a 50 mm thick mineral wool insulation on the exterior side of the gypsum board wind barrier and the impacts from climate change had the biggest effect on the moisture performance of the structure.

Improvement of the Process of Mechanical Dehydration of Five-Layer Wet Leather Semi-finished Products

To improve the process of mechanical dehydration of semi-finished wet leather products, a multilayer dehydration using felt materials – monshons was experimentally investigated. The process is conducted by vertical feed of semi-finished wet leather products on a base plate between rotating squeezing rollers. The D-optimal method of mathematical planning of the experiment and the Kano design matrix were used for conducting experiments. The multi-layer package consists of five layers of semi-finished wet leather products and two layers of moistureremoving materials between each layer, folded over the base plate. The studies were carried out in laboratory conditions on an experimental bench, taking into account the production parameters of processing. As a result of the study, mathematical dependences of the amount of removed moisture for each of five layers of semifinished wet leather product on the feed speed and the pressure of the squeezing rollers were derived. The analysis of the results showed that, with the existing parameters of mechanical dehydration, it was possible to simultaneously squeeze out moisture from five layers of the semi-finished leather product with a minimum pressure of the squeezing rollers and an average feed speed. The productivity of the technological process was more than five times higher in comparison with the productivity of similar roller machines. In the near future, this research methodology will be used to determine the technological factors affecting the extraction of excess moisture from a package consisting of ten semi-finished wet leather products and moisture-removing materials.

EFFECT OF MOISTURE ON NITROGEN DIOXIDE FORMATION IN LAMINAR FLAME OF NATURAL GAS

The paper contains the results of experimental studies of the effect of moisture on nitrogen dioxide formation and on oxidation of NO to NO2 in laminar premixed flame of natural gas. The water vapor is shown to be the third very influential participant, along with fuel and oxidizer, in the combustion process. Injection of moisture into the combustion zone has an effect due to the insertion of additional quantities of HO2- and OH– radicals into the process, which contributes to the intensification of the oxidation of NO to NO2. Introduction of the concept of the “excess moisture ratio” in the combustion process is proposed. The studies were executed at the laboratory installation in conditions of formation of the V-shaped laminar flame of natural gas behind a transverse cylindrical steel stabilizer, with determining the concentrations of flue gas components.

Technologies and technical means of production of complete feed and PMVA for agricultural animals

Russian market of complete feed recent years shows a steady development. Currently the Kurgan region the state of base of feed and a shortage of specialized feed additives leads to a violation of maintenance conditions for livestock, reduced productivity. The increase in production of concentrates and complete feed currently is an actual scientific and technical problem whose solution is of great scientific and practical importance. To solve this problem, the technology of production of animal feed and PMVA on the basis of full-fat extruded soybeans produced using a shaft cooler and sapropel dehydrated with the use of filtering centrifuges continuous action has been proposed. The proposed technology of production of animal feed and PMVA completely solves the problem of removing excess moisture from the sapropel immediately after the production and delivery of product to the shore. The process of extraction and preparation for use of sapropel reduced from several days or months (winter freezing) up to several hours.

Agrobiological foundations for growing woody energy crops on drained organogenic soils

The purpose of the work was to identify the most effective agrobiological measures of plantation cultivation of wood energy crops – various types of willow on drained organogenic soils of Forest-steppe and Polesie, to develop technologies for their cultivation and to carry out energy, economic and environmental assessments of their cultivation on land extracted from intensive cultivation. Research methods – field with a complex of biometric, agrochemical and laboratory studies, mathematical and statistical.The results of studies conducted on medium-deep drained old-time carbonate peatland are presented. Data on agroecological assessment of soil and climatic conditions of agricultural lands were obtained to create energy plantations in the area of excess moisture, agrochemical and water-physical properties and features of the water-air regime of organogenic soils were investigated. As a result of the analysis, the data found that they fully meet the requirements of growing high-performance energy crops.It has been established that the most effective way of basic soil processing is to plant willows in ploughed furrows with an area of food of 0,9 x0,7 m and harvest every two to three years. The most productive on average in five years was willow three-song – 27,1-28,0 t per hectare and willow rod – 23,2 and 31,7 t per hectare of dry mass in Forest Steppe and Polissya, 28,2 and 21,2 t per hectare, respectively. According to economic indicators, the highest conditional net profit (21,1 thousand UAH per hectare) and the level of profitability (305%) provided willow rod on the scheme of planting 0,9 x 0,7 m and cleaning in the form of chips every three years.

Study of Reducing the Damage and Reuse of Waste Tanks in the Certej Mining Area

The Certej area is an area of gold mining activities with a history of several hundred years. The only activity with a significant share in the area was the mining activity, which provided the population of Certeju de Sus commune and its surroundings with the means necessary for a decent living. In the case of tailings dumps, the soil suffers a combined impact - by removing large areas of land from the natural circuit and by generating acidic water. The geology and morphology of the region, characterized by the existence of surfaces with different slopes, are natural causes that attribute different levels of vulnerability to land at the onset of degradation processes by erosion, landslides and excess moisture. All these bring limitations in the use of land on the main uses: agricultural, forestry, construction, etc. The paper aims to provide solutions for the reuse of these lands, their use by recultivation, the search for plant species adaptable to soil conditions. A relatively small number of species were determined on the tailings dumps in the studied area, the spontaneous vegetation is visibly stressed by the existing conditions. As such, the method of ecological reconstruction of freshly deposited tailings dumps by the method of forest recultivation is proposed.