Advanced Materials Research Vol. 649

Abstract: This paper presents the results of the research undertaken by the authors in the frame of the postdoctoral program 4D-POSTDOC. After a short introduction on the actual status of structural design of airport pavements including geometrical and loading characteristics of complex loading gears, the modeling and the structural design of airport rigid pavements, constructed with conventional and various recycled materials, using the finite element method, is described. The main objective of this research program was to elaborate a design method which, beside the complex landing gear including six footprint tires, all specific parameters related with the recycled materials and with conventional and reinforce rolled compacted concrete (RCC) technologies are included. Finally, practical design diagrams for structural design of the concrete slabs, including their specific correlation function, used for the construction of the Airbus-A380 runway are presented.

Abstract: The term "passive house" refers to rigorous and voluntary standards for energy efficiency in a building, reducing its ecological footprint. There are many ways how to build a passive house successfully. These designs as well as construction techniques vary from ordinary timber constructions using packs of straw or constructions of clay. This paper aims to quantify environmental quality of external walls in a passive house, which are made of a timber frame, lightweight concrete blocks and sand-lime bricks in order to determine whether this constructional form provides improved environmental performance. Furthermore, this paper assesses potential benefit of energy savings at heating of houses in which their external walls are made of these three material alternatives. A two-storey residential passive house, with floorage of 170.6 m2, was evaluated. Some measurements of air and surface temperatures were done as a calibration etalon for a method of simulation.

Abstract: This paper presents the results of laboratory studies, undertaken by the authors, in the frame of 4D-POSTDOC research program :"Innovative technologies and logistical solutions for the reuse of demolition and construction waste in the construction of cement concrete and fiber reinforced cement concrete pavements". After the presentation of the main objectives of this research program, and of the specific characteristics of the demolition wastes investigated in parallel with those of conventional construction materials, the possibility of using these materials for the preparation of the roller compacted concrete (RCC) is investigated. Finally, conclusions on the influence of recycled aggregates and recycled steel fibers on the mechanical performances of RCC and technical recommendations for the use of this more efficient material and of the involved technology for the construction of sustainable road infrastructures are formulated.

Abstract: The paper discusses some issues connected to timber joist ceilings found not only in historical protected buildings but also in newly designed multi-storey timber based ones, with regards to their acoustic parameters perceived by the inhabitants of such objects. These problems are usually connected to the complaints of the users because of unsatisfying acoustic conditions indoors, observed mainly at low frequencies, even though the requirements given by the legislation are met. The paper with its content is a reaction to the contradiction between the results coming from measurements and subjective perception, and is complemented by structural evaluations seeking the effects of dynamic tremors and vibrations.

Abstract: This paper describes a modern composite timber - concrete ceiling construction. It also compares and evaluates the acoustic qualities (sound insulation and a level of acoustic pressure of impact sound), which were measured on a sample of a 3 x 3.6 m size in the experimental measurements in the acoustics testing laboratory certified by CSI Zlin. In the first case, the construction is evaluated as a supporting ceiling panel without any additional layers. In the second and third option it is evaluated as a ceiling construction with structural modifications (a supporting ceiling with some floor layers of different combinations).

Abstract: Through the use of a spectral analysis of the source of noise – person’s movement over the ceiling construction – it was found out that in this kind of noise distinctive low-frequency tone components occur (31,5 - 40 Hz) which is beyond the evaluation area of the impact sound insulation of the ceiling construction, s. [2], [3].

Abstract: This article brings up to discussion a particularly topical issue which is the quality of sound insulation in Slovakian dwellings. An analysis of the current acoustical situation in newly built or renovated buildings is shown, as well as the importance of a subjective evaluation of acoustical comfort is highlighted. Nevertheless, it is known that the acoustical comfort is one of the most important factors of a healthy living environment and that the acoustical defects often become subject of argumentation. Concerning the growing acoustical problems in dwellings, we could debate, to what extent the real value of the apartment can be estimated.

Abstract: Aerated concrete from the viewpoint of the transport of liquid moisture appears to be a material with highly variable properties strongly dependent on the porosity and liquid water exposure conditions. Saturation degree of aerated concrete strongly affects not only all its thermal-technical properties, but regarding to the risk freezing, also the strength properties. To predict the degree of saturation and moisture distribution, we used certain mathematical and physical methods supplemented with experimentally identified parameters. The aim of this paper is to discuss existing approaches to model capillary moisture transport in aerated concrete and description of the new, simplified 2D computer mathematical-physical model for the solution of this phenomenon. The results of the model are compared with experiments carried out. The conclusion discusses the limits of this new model, and mentions further possibilities for its improvement.

Abstract: Timber is one of the most used materials for roofing of ice arena because of its very good mechanical properties and low weight. High relative humidity of internal air, low temperature and ice rink presence, which cause fall of surface temperatures of constructions under the dew point due to radiation, are risky factors not only from structural point of view, when load bearing capacity of construction in time is reduced, but also from the view point of bio corrosion. Specific hygrothermal microclimate, different from air parameters in the ice arena, is formatted close to the individual members of roof construction. Newly developed mathematical and physical model using CFD simulation is used for simulation of hygrothermal stress in chosen part of the ice arena roof construction, which substantially affects quality, utility properties and life time of timber roof components. Results are compared with experiments in specific ice rink.

Abstract: The paper deals with the mathematical model of the multi-layer wall containing the phase change material (PCM). The model utilizes the effective heat capacity method for modeling the latent heat of phase change and the control volume method is used for the discretization of the model. The utilization of the model is then demonstrated on the problem of the optimal design of the multi-layer wall with the PCM. The TMY2 data for the city of Brno were used in simulations as operational conditions. The main attention is aimed at the determination of the optimal thickness of the PCM layer for the multi-layer wall design with various thicknesses of the masonry.