Jindrich Melichar

Experimental Testing of Hydroinsulating Injection Screens

One of the most widespread method of redevelopment of wet masonry is additional creating of hydroinsulating screen in the material. This method has many advantages. The biggest advantage is fact, that building can be repaired from inside without damaging its statics and saving it from being demolished, thus sparing the environment. In comparison to other procedures its application is quick, easy and has excellent final efficiency. Main object of this article is testing of application and total functionality of individual screens in masonry.

Penetration Rate of Various Injection Gels in Dependence on Wetness of Building Materials

Method of using hydroinsulating injection screens during redevelopment of wet masonry is nowadays one of the most efficient methods of treating rising wetness in old but also new buildings. One of the biggest advantages of this method is low damage to the building structure and the possibility of treating the masonry from the inside of the building. One of the aspects that has influence on injection screens functionality is wetness of treated masonry. The main object of this paper is to observe changes in the penetration rate of injection gels in dependence on wetness of building materials.

Laboratory Verifying of Injection Screens Efficiency

Nowadays is method of creating additional hydroinsulaitng injection screen in wet masonry quite widespread in Europe and also the rest of the world. The biggest advantages of this progressive method is fast and inexpensive application during which no harm to the construction is caused. Meaning, that damaging of buildings statics is not really possible. Final goal of this paper is to describe application and experimental testing of final efficiency of injection screens.

The Influence of Sulfates on Tobermorite Formation in Lime-Ash Composite

Autoclaved aerated concrete is an ecological building material with suitable properties and long-time tradition. The research of secondary raw materials usage and technology optimization is needed in order to increase the efficiency and sustainability of its production. It is important to focus on development of mineralogical composition while studying the influence of input materials and the parameters of hydrothermal synthesis on the properties of final product. This is especially important in case of tobermorite formation as the bearer of strength in the structure. Main focus of this paper is applicability of fly ash (silica component) and admixture of energo-gypsum (sulfate component) in production of lime-ash composite in hydrothermal conditions. The research was focused on autoclaving of samples at temperature of 170°C in three various isothermal sustains. Final samples were analyzed by XRD and SEM in order to proof the influence of input materials. Results show that 5% admixture of energo-gypsum had positive influence on tobermorite formation.

Content of Aluminium Hydroxide in Lime-Silica Composite and its Influence on Tobermorite Formation

Aerated concrete is lightweight building material with excellent thermos-technical properties compared to its strengths, easy workability and economic efficiency. It is material with long tradition of manufacturing since 1924 but its potential is yet possible to be extended. Since the beginning pure ingredients such as lime and silica sand has been used. Nowadays we are looking for ways to replace these expensive raw materials with cheaper alternatives. One of the most important mechanical properties of each material is its strength. In case of aerated concrete the bearer of strength is mineral tobermorite. It is created by reaction of silicon oxides and lime at hydrothermal conditions. It belongs to the group of calcium hydrosilicates with chemical formula Ca5Si6O16(OH)2·4H2O. Main goal of this paper is proposal for modification of the raw materials composition and autoclave regime of aerated concrete using aluminium hydroxide in order to improve final mechanical properties and mineralogical composition.

Polymercement Composites in Environment with Increased Concentration of Sulfate Ions and Extreme Temperatures

Polymer cement matrix based materials were designed within the frame of the research presented in this paper. Resistance of these materials to combination of several adverse factors was observed. Considerable proportion of input materials used were components from alternative material resources. Primary binder was replaced with fly ash and blast furnace slag. Dominant proportion of filling mass was taken up by agloporite – porous aggregate produced by self-baking from fly ash. The focus of the research was assessment of degradation of materials after long-term exposition (up to 90 days) to increased concentration of sulphate ions and high temperatures. Degree of degradation was evaluated on the basis of physico-mechanical and physico-chemical tests combined with microstructural analyses.

Lightweight Aggregate Produced with Cold-Bonding of Fly Ash and Binder

Main object of this paper are results of ash usage in order to create artificial aggregates. Ashes are mineral residue of coal burning in thermal power stations. Fly ashes (high temperature ashes) are highly used in practice as supplement of cement and silicate components of silica materials. FBC ashes are not used such great scale. They can be used for restoration, mounds or for example also for production of ash autoclaved aerated concrete. [1] Production of artificial aggregate from sintered ash is possible mainly because of the fly ashes. [2] Focus of this paper is to compare various types of ashes for lightweight aggregate produced with cold-bonding. Apart from the fly ashes and FBC ashes are also tested bottom ashes from FBC technology. From the results could be assumed, that bottom ashes compared to their granularity could be used only very hardly. Fly ashes splendidly react with cement and reach higher strengths. But they need more than 10 % of binder in order to reach quality results. FBC ashes better cooperate with quicklime, but in order to reach suitable parameters they need smaller portion of binder.