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This study presents a new approach towards the production of sol-gel silica-coated Bi2O3/Gd2O3 cement additives towards the improvement of early mechanical performance and radiation attenuation. Two types of silica coatings, which varied in synthesis method and morphology, were used to coat Bi2O3/Gd2O3 structures and evaluated as a cement filler in Portland cement pastes. Isothermal calorimetry studies and early strength evaluations confirmed that both proposed coating types can overcome retarded cement hydration process, attributed to Bi2O3 presence, resulting in improved one day compressive strength by 300% and 251% (depending on coating method) when compared to paste containing pristine Bi2O3 and Gd2O3 particles. Moreover, depending on the type of chosen coating type, various rheological performances of cement pastes can be achieved. Thanks to the proposed combination of materials, both gamma-rays and slow neutron attenuation in cement pastes can be simultaneously improved. The introduction of silica coating resulted in an increment of the gamma-ray and neutron shielding thanks to the increased probability of radiation interaction. Along with the positive early age effects of the synthesized structures, the 28 day mechanical performance of cement pastes was not suppressed, and was found to be comparable to that of the control specimen. As an outcome, silica-coated structures can be successfully used in radiation-shielding cement-based composites, e.g. with demanding early age performances. [ABSTRACT FROM AUTHOR]

This study presents the results of the analysis on the energy balance of a single-family residential home built in 1986. The authors assess the proposed construction improvements in terms of their ability to enhance the building's energy efficiency and comfort. The studies were carried out for the needs of the owners who saw the necessity of reducing the maintenance and heating costs of the house and of improving their living conditions. The on-site studies and analyses of the building concerning the calculations for the proposed variants of solutions have pointed to the necessity and relevance of a thermal modernization of the building. The analyses took into consideration the growing requirements of thermal insulation of walls, the EP factor and the growing use of energy from renewable sources. The proposed modernization steps and energy audit calculations helped to select the most efficient solution.

Due to its numerous technical advantages as well as health benefits, sand-lime brick is increasingly used in the construction of brick walls, especially in residential buildings. Unfortunately, the occurrence of damp leads to a sharp deterioration of the technical properties of the material and the environmental conditions inside the building. Given the importance of this issue, an attempt was made to diagnose the extent of dampness variability of the main hygrothermal and strength characteristics of calcium silicate products. The study involved the basic material properties (density in dry and water-saturated conditions), moisture-related properties (capillary adsorption coefficient and sorptivity), thermal coefficients (thermal conductivity and volumetric heat capacity) as well as mechanical properties (compressive strength). This article describes diagnostic studies that were conducted to assess the extent of the effect of dampness on the strength of sand-lime products. In order to render the diagnosis more comprehensive and to include a wider range of silicate blocks available on the market, it was decided to examine three groups of silicate blocks (strength class 15, 20 and 25) obtained from three different factories. It was demonstrated that for all the examined groups dampness caused a significant decrease in compressive strength ranging from about 30% to about 40%.

The aim of this study was to acoustically assess selected sacred buildings located in Szczecin. The research part contains the research methodology and the results obtained. The research was carried out using two methods. The first one is the integrated impulse response method where, using a bursting balloon, the time of sound pressure drop was measured at selected points of the object. In the second research method, the interrupted noise method, the sound pressure drop was measured after the noise generated by the omnidirectional loudspeaker had ceased. Reverberation time was calculated for the results obtained, which is the main and basic parameter determining the interior acoustics. On the basis of the above-mentioned measurements, the reverberation indicators for the temples were also calculated. When analysing the components of the reverberation indicator, it was noticed that poor acoustics in the sanctuary concerns speech, while interior acoustics is good for the reception of organ music. In the analysed church, the reception of liturgical music is also better than the reception of speech, but the differences between these values are small. [ABSTRACT FROM AUTHOR]

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The aim of the research was to determine how the admixture of nanosilica affects the structure and mechanical performance of cement concrete exposed to high temperatures (200, 400, 600, and 800 °C). The structural tests were carried out on the cement paste and concrete using the methods of thermogravimetric analysis, mercury porosimetry, and scanning electron microscopy. The results show that despite the growth of the cement matrix's total porosity with an increasing amount of nanosilica, the resistance to high temperature improves. Such behavior is the result of not only the thermal characteristics of nanosilica itself but also of the porosity structure in the cement matrix and using the effective method of dispersing the nanostructures in concrete. The nanosilica densifies the structure of the concrete, limiting the number of the pores with diameters from 0.3 to 300 μm, which leads to limitation of the microcracks, particularly in the coarse aggregate-cement matrix contact zone. This phenomenon, in turn, diminishes the cracking of the specimens containing nanosilica at high temperatures and improves the mechanical strength. [ABSTRACT FROM AUTHOR]

The aim of the research was to determine how the admixture of nanosilica affects the structure and mechanical performance of cement concrete exposed to high temperatures (200, 400, 600, and 800 °C). The structural tests were carried out on the cement paste and concrete using the methods of thermogravimetric analysis, mercury porosimetry, and scanning electron microscopy. The results show that despite the growth of the cement matrix's total porosity with an increasing amount of nanosilica, the resistance to high temperature improves. Such behavior is the result of not only the thermal characteristics of nanosilica itself but also of the porosity structure in the cement matrix and using the effective method of dispersing the nanostructures in concrete. The nanosilica densifies the structure of the concrete, limiting the number of the pores with diameters from 0.3 to 300 μm, which leads to limitation of the microcracks, particularly in the coarse aggregate-cement matrix contact zone. This phenomenon, in turn, diminishes the cracking of the specimens containing nanosilica at high temperatures and improves the mechanical strength.