Šárka Keprdová

Usability of Fly Ashes from Czech Republic for Sintered Artificial Aggregate

Artificial sintered aggregate produced by self-firing is one of the few building materials, which can be produced with only fly ash. If the character of the fly ash is optimal, no other additions are needed. However, not every fly ash has optimal composition. Quality of fly ash then influences composition of the mix, technological parameters and quality of produced aggregate. Parameters influence the process of self-firing, strength of granules during the phases of drying process, ignition and burning under given underpressure on an agglomerating bed. This often influences correct setting of proportion of combustion material and reduces quality of aggregate. The paper evaluates fly ash produced in the Czech Republic by both high temperature and fluidized bed combustions. Their granulometry, specific surface, bulk weight, structure, chemical composition and behavior at higher temperatures up to the melting point are evaluated.

Study of Alternative Raw Materials Parameters for Modification of Cement-Bonded Particleboards Composition

The cement-bonded particle boards can be used among other also with reconstructions of various types of buildings as a part of final surface treatment. The paper deals with partial results of the research focused on optimisation of cement-bonded particle board composition with alternative raw materials. Specifically it is analyzing of basic parameters of the waste originating during processing (modification of surface format and quality) of the boards. Upon results and findings a design of new formulas of cement-bonded particle boards is mentioned further, i.e. the composition modified with above stated waste. The outputs presented in the article form an important initial information source in the solved questions. In view of subsequent phases of the research it is a relatively essential and also it can be said a key phase.

Possibility of Using the Technical Hemp as a Filling Component in External Thermal-Insulation Composite Systems

Combining air or hydraulic binders with hemp shives, we can gain a set of new building materials. These products achieve excellent performance characteristics for durable, environmentally sustainable buildings. Being together, these products create natural composite building material that can be used to create insulating elements for walls, floors and roofs and also to create excellent thermal and acoustic properties of the buildings. Hemp insulation material is created by connection of technical hemp shives with a binder consisting of cement and calcium hydroxide. The production process may vary depending on whether the hemp is mineralized or not. It can be generally said that dry components should be mixed at first (binder and shives) and then water should be added. During the production, all components of insulating material must be perfectly mixed. The paper deals with the proposal and testing of new hemp insulation composites. Tests of the hemp insulation described in this paper are not typical representatives of the tests of insulation materials. Due to the doubts about the insulating properties of the proposed material, there was testing carried out in such the ways as if it was the filling material based on lightweight concretes.

Effect of Artificial Lightweight Aggregate on Resistance of Polymer Cement Mortars to Extreme Temperatures

This paper presents the results of research focused on the modification of composition of the polymer-cement mortars. The use of these materials is quite wide. The greatest use can be found in the production of reinforced concrete repair materials. Specifically, the article analyzes problems of lightweight aggregate effect on the resistance of polymer-cement mortars to extremely high temperatures. The link is particularly evident with the risk of fire. Attention was given to the two different types of aggregates - from primary raw materials (Liapor) and alternative sources of raw materials (fly ash aggloporite). The study was carried out by the laboratory analyzing the basic material characteristics of prepared samples which were exposed to temperatures up to 1200 ° C.

Parameters of Cement Bonded Particle Boards Modified with Stone Wool Fibre

The contribution deals with possibilities of using waste from the production of stone wool for modification of the existing composition of cement boards . Waste - the fibres from the production of stone wool - was used as an alternative to the standardly used wooden filler (chips, sawdust). The waste was tested in laboratory and then added to the mixture for the production of cement-bonded particleboards as a substitute for wood filler. The physical and mechanical properties of laboratory-made boards with a modified recipe were monitored.

Application of Alternative Fillers in the Cement-Bonded Particleboards Structure

Cement-bonded particleboards merge the good properties of wood and cement; they are board materials with properties which are pre-determined for use in many different cases in the case of construction of walls and partition walls, lower ceilings, facades, floors, etc. The disadvantage of the cement-bonded particleboards is the relatively high price which is mainly derived from the price of input materials. The main component creating the filler for cement-bonded particleboards is wood. Wooden chips are produced from tree trunks of cut trees which mean that, first of all, it is necessary to produce chips from the wooden substance. By using alternative fillers, it is possible to partially or wholly avoid this part of the production. The use of alternative raw materials in construction materials means there is the opportunity to decrease manufacturing costs and eliminate ecological loads. The content of this paper is the use of alternative fillers as an organic, as well as inorganic origin in the structure of cement-bonded particleboards. For the production of boards, technical hemp was selected, straw and jute as representatives of the most often used organic raw materials followed by a narrow fraction of Refaglas cellular glass, synthetic fibres and waste from the production of ORSIL mineral wool. In the board structure, this concerned 100% or 50% substitution of wooden splinter. For the valorisation of options for future use in board materials, physical-mechanical properties were monitored; in particular, attention was paid to bending strength, modulus of elasticity in bending and bulk density. Newly created boards must fulfil the technical parameters required for cement bonded particleboards stated by the standard EN 634-2.

The Influence of the Addition of Secondary Materials to the Thermal-Technical Properties of Filling Materials

The filling material is made up of technical Cannabis shives, hydraulic or air binders and other components. They are suitable for use as fillers in horizontal or vertical wooden structures such as rack systems. Thanks to its good thermal-insulating properties the filler may be used as thermal insulating filler in walls or floors. The article describes the behaviour of Cannabis padding materials used as secondary raw materials as the replacement part of the joiner component. The use of secondary raw materials (such as fly ash, fluid or classical slag), however, is conditioned by the maintenance of the same, or at least the best possible thermal-technical parameters of the resulting filling material.

Cement-Bonded Chip Boards Using Hemp and Energy by-Products in Civil Engineering

The aim of the research presented in this article was studying the basic physico-mechanical parameters of cement-bonded chip boards with hemp used as filler and by-products of energy production applied when modifying the bonding component. Determining and evaluating the basic parameters of boards of modified composition allowed for assessment of the effect of adding or substituting the bonding component within the cement chip board matrix. The work focused on the flexural strength, modulus of elasticity and density. In terms of anomalies in the cement matrix, i.e. uncommon crystalline phases in cement composites, representative samples were selected for differentially thermal and X-ray diffraction analysis.

Application of Technical Hemp into the Structure of Cement-Chip Boards

Cement-chip boards are building elements that combine the advantageous properties of wood and cement. It is this synergistic effect which determines the versatile use in the building industry. The boards can be used in any place where the favourable properties of this construction material can fully be appreciated. The disadvantage of the cement-chip boards remains in their relatively high price. Reduction of the price and possible improvement of physical and mechanical properties can be achieved by partial substitution of the raw materials. The basic ingredients of the cement-chip board include the binding material (cement) and filler (wood). The filling material may be partially replaced by secondary raw materials or completely replaced by other herbal sources, such as technical hemp. As the individual components mutually influence each other and, as their effects may not only be added up (additive effect), but also mutually reinforced (synergistic effect), it is not so easy to determine the optimal recipe as it may seem at first sight. This article deals with the use of technical hemp shives as a replacement of filling component of the cement-chip boards. To evaluate the possibility of future use of the boards in building structures, the physical and mechanical properties were monitored. Special emphasis was placed on tests of flexural strength, modulus of elasticity and volume weight. The mixture must meet the technical parameters related to the cement-chip boards.