Papers by Keyword: Thermal Insulation

Abstract: In this paper, the thermal behavior of concrete blocks with different rubber ratios was examined experimentally. The rubber of 0%, 5%, 10%, 15%, and 20% used instead of fine aggregate in a concrete block raw materials. The size of the rubber granules used in this study is between 0-1 mm. The concrete approved mixing ratios are 1:2:1. The indoor solar simulator with 700 w/m² light intensity was applied on the external surface of each block and thermocouples were used to measure the temperature on the external and internal surfaces. The other block surfaces are insulated. The results indicated that the use of rubber aggregate with the concrete block reduced the inner surface temperature by increasing the thermal resistance of the heat flux. ​For 20% rubber added, produce 8.5% low-weighted construction materials and with high thermal resistance that works to save energy consumed in the building sector.

Abstract: As the need to ensure thermal comfort in buildings is constantly evolving, new technologies continue to emerge with the aim to develop efficient thermal insulation materials. This study aims to explore a textile technology using Airlaid process to develop non-woven fabrics made of natural fibers extracted from Posidonia Oceanica’s waste for assessing their suitability for insulation products in construction field. This technology offers the feature to develop isotropic non-woven structures by orienting randomly the fibers on the fabric surface. The web composed of a mixture of Posidonia Oceanica fibers and a proportion of thermoplastic fibers is then thermally bonded in an oven followed by cooling in order to ensure the solidification of the bonding areas. The prepared panels are then analyzed for the thermal conductivity. It was found that their thermal conductivity is close to commonly used thermal insulation materials, ranging between 0.03515 W/m.K and 0.03957 W/m.K, which allows the non-woven panels to compete with widely-used insulation materials for building’s field. The second part of this work aims to determinate the Posidonia panel's resistance to five common mold types in buildings (Aspergillus niger, Penicilum funiculosum, Trichoderma viride, Chaetomium globosum, Paecilomyces variotii). In fact, at high moisture content, molds are likely to develop on cellulosic materials affecting indoor air quality and eventually causing a variety of health risks to occupants. However, optic microscope results showed no growth of molds on the Posidonia samples which allows conceiving reliable thermal insulation materials.

Abstract: The precast concrete elements in the construction of buildings are increasingly used due to their better quality control, constructive speed, reduction of the number of workers and less waste of resources compared to conventional construction; for wall applications, to these advantages, the design to ensure thermal comfort requires the improvement of the low thermal insulation of conventional concrete panels. The use of materials with lower thermal conductivity such as Expanded PolyStyrene Beads (EPSB) in lightweight concrete for the construction of precast panels in housing, contributes to improve thermal insulation and the saving operational energy during its operation phase, because the aggregate has a small size, low density and thermal conductivity; applied in higher volumes in concrete, reduces indoor heat loss in cold climates and indoor heat gain in warm climates in housing. The purpose of this research is to study the behavior of lightweight concrete with EPSB for 16%, 26% and 36% addition and evaluate the air-dry density, compressive strength, thermal conductivity, relationship between air-dry density with compressive strength and thermal conductivity. The results indicate that the higher the percentage of EPSB the air-dry density, compressive strength and thermal conductivity decrease; the relationships between air-dry density with compressive strength and thermal conductivity follow a linear trend and are similar.

Abstract: The aim of the researches is to identify indicators of longevity of the mineral wool products in the course of their use as an insulation layer of building envelope of construction projects with the working life up to 100 years. The objectives of the research consisted in evaluating changes of the operational characteristics of material – thermal conductivity, air permeability, compression strength at 10% linear deformation, specimen appearance and geometric parameters under cyclic climate effects that simulate environment effect on the state of the thermal insulating materials of building envelopes in the course of operation of construction projects.

Abstract: Undoped ZnO and Ag-doped ZnO were prepared to use as near-infrared (NIR) shielding by simple precipitation method with zinc acetate and zinc nitrate as Zn precursor and silver nitrate as Ag precursor. The Ag-doped ZnO and undoped ZnO were characterized by XRD, SEM, and UV-vis-NIR spectrophotometer. The NIR reflectance performance reveals that Ag-doping improves the NIR shielding and optical property of pure ZnO. The 10 mol% Ag loading shows the lowest reflection in the visible region of about 15% and the highest reflection in the NIR region of about 50%. It not only shows the best NIR reflection but also exhibits the best thermal insulation. It reduces the inner temperature of the in-lab setup to mimic a house by 7.5°C when compared to the uncoated glass window. It is concluded that 10 mol% Ag-doped ZnO nanoparticles can result in UV-NIR shielding coatings.

Abstract: The prospects for the use of foam glass in construction were described. The modern compositions of foaming mixtures for foam glass synthesis were considered. Compositions for studying the influence of the foaming mixture components on the formation of foam glass porous structure were developed, their internal structure and properties were studied. The role of each component of the mixture on its foaming was revealed. Glycerol is a pore-forming agent, which decomposes and produces foaming gases. Waterglass is a stabilizing agent reducing glycerol combustion process. Recommendations on the application of the described patterns in the foam glass synthesis were given.

Abstract: On the base of volcanic glass - perlite, the energy-efficient technology of cellular glass for heat-insulating purposes has been developed. Compositions of nanosized modifier and redox gas formers were developed by the method of experimental-statistical modeling and optimization of probability parameters, allowing to obtain cellular glasses with low average density and almost closed porosity in a single technological process at technologically acceptable temperatures. In the production of cellular glasses (foam glass) of new generation, based on natural glassy rocks of silicate and aluminosilicate composition modified with sodium hydroxide, in the presence of water and gas-forming additives, during mixing and sintering, the components react at the nanoscale level to form glass under low softening temperature and sufficient quantity of foam stabilizers. The main scientific results - the use of nanotechnological modification of amorphous silicate and aluminosilicate rocks in the technology of cellular glass for construction and technical purposes, the development of compositions and method for the production of cellular glass using energy-saving technology with the following performance parameters: average density of 115...250kg/m³, coefficient of thermal conductivity 0,051...0.075W/(m•K), water absorption 1.6...4.0%, compressive strength 0.14...4.20 MPa, hydrolytic glass class I...III.

Abstract: The article studies one of the aspects of the heat-insulating multifunctional shells use - the cold preservation. Such task is relevant for cold storages, workshops and warehouses, in which low temperatures constant maintenance is necessary, for sports facilities (for example, ice rinks and ski facilities). In all cases of application, the main goal is to achieve the economic efficiency, which is expressed in functional results (preservation of the material that breaks down at positive temperatures) and in energy savings. The use of polyethylene-based shells, which are connected by a lock joint, is substantiated. The experimental studies results of the material given in the article shows that in terms of resistance to low and alternating temperatures, operational durability, tensile strength and water absorption, this material and insulating shells based on it are quite applicable for insulation of cold-saving objects. The experience of using heat, vapor and moisture insulating shells based on polyethylene foam with the equipment of frameless and frame structures, sports facilities, as well as for the preservation of snow at ski resorts is also provided in the article.

Abstract: The paper presents a brief overview of the thin-layer thermal insulation paints used now and their characteristics. A new composition of thin-layer heat-insulation coating is proposed. The introduction of solid phases of non-autoclaved foam concrete with the average density D150 with high values of the standard entropy of formation in it is scientifically substantiated from the point of view of increasing the thermal protection properties. It is shown that such phases have an advantage in comparison with the solid phases of the glass and ceramic microspheres used now. It is also proved that the presence of thin-layer thermal insulation coating of nanoscale particles in the form of silica in the composition favours the reflection of the incident heat flux due to the Tindal effect and provides an increase in the polydispersity of the composition. The calculation of the resulting composition by the Van Vleсk formula used in the classical science is given.

Abstract: The trend of achieving sustainable development in the area of new, eco-friendly materials remains topical for many experts concerned with developing new materials applicable worldwide in civil engineering as well as elsewhere. Our research team has for many years been developing non-traditional materials that meet the current requirements. These materials are made with organic fibers – waste natural fibers produced by agriculture or waste industrial (locally produced) fibers. Their thermal and acoustic insulation properties are very close to those of conventional insulation materials (expanded polystyrene, extruded polystyrene, mineral wool, polyurethane foam), which are still finding broad use in the Czech Republic despite their harmful impact on the environment. The paper focuses on the various uses of several types of textile fibers (mainly by-products) in the development of modern insulation materials with a high value added. These materials bear several specific advantages over conventional insulations, which enable, among others, easier installation. Some of the newly developed insulations can also be used as core insulations in the manufacture of vacuum insulation panels (VIP).