Materials Science Forum Vol. 824

Abstract: The sustainability principles in building sector promote a development of new building materials and products directly designated for improvement of the thermal performance of buildings related to the energy saving for the interior climate conditioning. In order to comply with this concept and improve the thermal comfort of buildings environment, incorporation of phase change materials (PCMs) into the construction elements giving ability to store and release heat looks like a beneficial material solution. On this account, the mechanical, rheological and thermal properties of cement-lime dry plaster mixture with addition of 4, 8 and 12 mass% of PCM water dispersion are experimentally investigated in the paper. The increasing amount of applied PCM admixture causes the significant improvement of the plaster heat storage capacity in dependence on temperature exposure applied in the performed DSC experiment. Contrary to this positive finding, the higher content of tested polymer microencapsulated PCM in plaster matrix leads to the lower mechanical strength. However, it is still sufficient for construction applications.

Abstract: Recycled finely crushed brick appears to be a suitable additive to lime or cement binder in render mixtures. This waste material indicates good pozzolanic properties and actively takes part in formation of chemical bonds in materials structure. The main objective of this paper is to find an appropriate ratio of waste crushed brick that is used as a replacement of other constituents represented by lime hydrate and silica sand. Besides it aims to find out a perspective utilization of such a waste material. Finely crushed brick originates from the production of thermal insulating brick blocks which is ecologically and economically advantageous. In this work, results of measured material parameters of render mixtures with different replacement ratios of binder (lime hydrate) and simultaneously filler (silica sand) by finely crushed brick are presented. Among the studied parameters basic physical properties (measured by water vacuum saturation method and by helium pycnometry), characterization of pore system (by mercury porosimetry) and thermal characteristics are presented.

Abstract: The design of the new lightweight material containing stone dust as a foaming component is described. For the composition of the material with desired properties the simplex sequential optimization was used. As an optimized value the complex point criterion was formed.The new low-cost and environmentally friendly material was designed by the help of the optimization software SOVA 1.0. The bulk density of lightweight gypsum was under 600 kg/m³ and its compressive strength was 1.1 MPa.

Abstract: New type of commercial plaster which is not well known in the market is investigated in this paper. It is a new product delivered from Turkey, contains 80% of perlit, the binder is unknown and according to the producer it is some type of polymer. According to the producer’s data, the open porosity is 80% and the main advantages are good thermal and mechanical properties. The data in the technical data sheet are not complete, some important information is missing, therefore the basic physical, mechanical, thermal and hygric properties were studied in this paper. Moisture diffusivity, thermal conductivity and specific heat capacity are determined as a function of moisture content. Obtained data were compared with ordinary lime-cement plaster. The results can be further utilized in the computer simulation for service life assessment studies.

Abstract: The effect of metakaolin and hydrophobic agent admixture on properties of newly designed lime plasters is analysed in the paper. The overall majority of physical - chemical building deterioration is related to the penetration of moisture and soluble salts into the building structure. For that reason, the modified lime plasters were in the wide range of various properties tested. Comparative measurement declared the usage of metakaolin and zinc stearate does not significantly influenced basic physical parameters and water vapour transport, but reduced the liquid water transport which is very positive finding.

Abstract: The powder materials containing active SiO₂, which are used as pozzolanic active materials in cement mixtures, can be classified in consideration of their pozzolana activity, particle size or reactivity. In this paper, several types of metakaoline are studied using Frattini and modified Chapelle test for pozzolanic activity determination. The particle size analysis is measured using the laser diffraction analyser and the differences in the chemical composition are characterized by FTIR spectroscopy. The obtained data show influence of particle size and chemical composition of tested powders on their pozzolanic activity, which corresponds with the results of Frattini and modified Chapelle test.

Abstract: Crushed brick (CB) used in high strength concrete as partial replacement of cement is the subject of this paper. It is a waste material and so its exploitation is needed to be found. Concrete industry can be proper area as CB is a fine material and is pozzolanic active. Basic physical properties and mechanical properties were investigated. Open porosity and bulk density achieved the best values when 30% of cement was replaced by CB. Matrix density decreased with rising addition ratio. The values of compressive strength was the highest for 30% replacement level and with 60% addition ratio were not lower than for the reference mixture. The conclusion is, that according to studied parameters 30% of cement substituted by CB is the most profitable addition ratio.

Abstract: We study the hydration and pozzolanic reactions of cement pastes made from Portland cement (CEM I 32.5 R) from the Czech Republic as a function of age, using thermogravimetry. The measurements are done for 2, 7, 28, 90, and 180 days cured samples in order to monitor the rate of hydration. The investigation is performed in the temperature range from 25 °C to 1000 °C with a heating rate 5 °C/min in an argon atmosphere. The mass change during the decomposition of calcium silicate hydrate gels, portlandite, and calcite are determined, and the changes in the portlandite amount are estimated in dependence on the time of hydration.

Abstract: Present paper deals with experimental study of refractories manufactured with environmentally friendly materials. Performed research was focused on the development of new type of high temperature resistant composites with mineral addition applied as cement supplementary material. To reach suitable resistance to temperatures was chosen binder system based on aluminous cement which was modified by metashale. Developed composites went through the gradual thermal loading and residual mechanical and basic physical properties were investigated. Realized program confirmed good potential for practical utilization of metashale as an aluminous cement replacement. Present research offer an interesting way of reducing of costs and negative environmental impacts.