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Archiv článků od 26.6.2017 do 7.6.2019

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7.6.2019
Ing. Tomáš Žlebek, Ing. Jakub Hodul, prof. Ing. Rostislav Drochytka MBA, DrSc.

This work is focused on the verification of the possibility of using specially modified hazardous waste, solidification product, formed from selected secondary raw materials as solidifying agent and hazardous waste (end-product) as a filler in polymer grout joint material. Totally, two solidification technologies were verified, the first one was wet granulation of raw materials and another one was dry homogenization. It is more advantageous to use dry homogenization technology, which is economically less demanding. The possibility of using a specially modified filler was verified by the appropriate tests, and results showed that the grout joint showed high compressive strength of approximately 50 MPa, flexural strength up to about 20 MPa. Developed material can also be characterized by very good cohesion with the cast basalt.

ilustrační obrázek © Aisyaqilumar - Fotolia.com
10.4.2019
prof. Ing. Alena Kohoutková, CSc., Ing. Hana Hanzlová, CSc., doc. Ing. Jan Vodička, CSc.

Fibre-reinforced concrete is increasingly used in structures where its properties can be utilized - especially tensile and residual strength after cracking. For applications in load-bearing fibre-reinforced concrete structures, it is necessary to ensure the uniformity of the steel fibres distribution in its structure. The paper summarizes the current knowledge of fibre-reinforced concrete production and test methods, which can be used to monitor the uniformity of fibres distribution in both fresh and hardened fibre-reinforced concrete.

Jakým nátěrem ošetřit dřevo dubu v exteriéru
14.1.2019
doc. Ing. Miloš Pánek, Ph.D., Ing. Eliška Oberhofnerová, Ing. Ondřej Dvořák, Ing. Přemysl Šedivka, Ph.D., doc. Ing. Aleš Zeidler, Ph.D., Ing. Jakub Kaloč

Oak wood is characterized by good durability against biotic damages. However, its surface treatment by coatings is problematic, especially in the exterior expositions. In most cases, there is a rapid degradation and damage caused by weathering. Transparent variants of coating systems suffer from this phenomenon even more than pigmented ones. The article contains the results of practical experiments that lead to some general recommendations, which use leads to surface treatment of oak wood in exterior with longer durability and better colour stability.

12.12.2018
Ing. arch. Lenka Bažíková, VUT v Brně, Fakulta architektury, Ústav stavitelství

The mechanical properties of earthen building material have been intensively investigated for the last fifty years. Different earth mixtures are used for different building technologies, such as walls, bricks or plasters. Therefore, it is almost impossible to set a specific numerical value for a parameter in general. These values may vary significantly and are listed within range. The properties of each earth mixture are dependent on the clay content (type of clay minerals), filler, water and additives. Depending on the building technology several tests can be performed to determine the mechanical properties. This review article discusses mechanical properties of earth, the tests and limit values. These properties include density, binding force, compressive strength, tensile strength, bending tensile strength, bond strength, resistance to abrasion, modulus of elasticity and impact strength of corners.

6.12.2018
Ing. Jakub Diviš, Ing. Jan Růžička, Ph.D.

The paper summarizes latest research on the influence of natural clay materials and earth structures on the quality of indoor microclimate regarding relative humidity. This laboratory research has been carried out at FCE CTU in Prague and UCEEB CTU in Prague and focuses on the dynamic sorption properties of building structures based on natural clays compared to building structures based on common building materials.

16.10.2018
Ing. Iveta Nováková, Ing. Karel Mikulica

Due to increasing amount of construction and demolition waste (C&DW), new recycling methods and applications of secondary raw materials are searched. The biggest part of C&DW is old concrete and mortar which can be used for production of recycled concrete aggregates (RCA). To protect the nature and decrease amount of mined natural aggregates, RCA could partially or totally replace natural aggregates used for production of new concrete. This article presents the factors which have influence on the RCA properties. Properties of three different types of RCA were analysed and results compared with properties of natural aggregates. Description of connection between factors and properties of RCA are discussed. Results showed that not only origin and amount of impurities has influence on applicability of RCA as a replacement of natural aggregates for new concrete production.

EPD Liptovská Kokava
6.8.2018
Ing. arch. Miroslav Ščudla, Ph.D., ČVUT v Praze, Fakulta architektury, Ústav navrhování II.

In contemporary architecture, straw is used marginally, mostly in do-it-yourself construction. Although the convenient qualities of straw have long been known, it has not gained the trust of builders and designers. Construction companies have not learned to work with straw on a regular basis. In the scope of green technologies, an opportunity is emerging to use straw in professional building systems suitable for sustainable architecture. If we want to apply it in our architectural designs, we have several possibilities. The common small straw bales are suitable for many ways of structure and do-it-yourself process. This way of building process can be interrupt by logistic problems or weather disaster. Contemporary building market offers professional products made of straw: universal strongly pressed boards or system of modular units for external walls. All these ways of application are able to gain the high building quality. The innovative straw technologies enable to design and erect the energy passive house with considerable percentage of straw in constructions. Although the advantages of straw are indisputable, the next success of straw building materials depends on the interest of architects and builders.

23.7.2018
doc. Ing. Jaroslav Sandanus, PhD., doc. Ing. Kristián Sógel, PhD.

In the paper the refurbishment of riding`s hall roof structure is presented. The combined steel-timber load-bearing structure had visible and high horizontal deformations and the gable wall was pushed out of the building.In the frame of refurbishment the diagnostic survey, structural calculations of the original and the new stage of the structure and the proposal of refurbishment works were worked out.

18.6.2018
Ing. Zdeněk Vejpustek, Ph.D., doc. Ing. Bohumil Straka, CSc., doc. Ing. Jan Vaněrek, Ph.D.

This paper shows the process of restoration, of a historic wooden ceiling, using a “dry method” – interaction between historic timber joists that are mechanically jointed with wood-based boards.The paper describes reasons for choosing the method and principles of a good design. The experience of using this method on site is also described in this article.

21.5.2018
doc. Ing. Milan Gaff, Ph.D., Ing. Kamil Trgala, Ph.D., Ing. Tereza Adamová

Wood and the materials on its basis fulfil the requirements of an ever-evolving and accelerating society. In addition to naturally grown wood, wood-based materials are frequently used as a basic material for production of furniture and for building constructions as well. Looking at changes in waste management, a significant shift from the waste to the circular economy can be observed. The valuable raw materials are kept in the production cycle instead of landfilling or burning. Wood and wooden products can be efficiently separated in waste management, reused and recycled. The so-called wood waste – old furniture, wooden pallets, window and door frames, demolition wood, used lumber, bark and other wood residues can be reused in particleboard production. Particle board manufacturers in the Czech Republic have adopted progressive waste management and currently use 60% of recycled wood into particle boards. A completed life cycle analysis (LCA) of OSB demonstrates that replacing of 50% of natural fibres with recycled wood has significant environmental benefits. The objective is to push furthermore on effective legislation to promote waste material utilization and thus lead to a more sophisticated waste wood collecting.

14.5.2018
doc. Ing. Milan Gaff, Ph.D., Ing. Kamil Trgala, Ph.D., Ing. Tereza Adamová

Wood and the materials on its basis fulfil the requirements of an ever-evolving and accelerating society. In addition to naturally grown wood, wood-based materials are frequently used as a basic material for production of furniture and for building constructions as well. Looking at changes in waste management, a significant shift from the waste to the circular economy can be observed. The valuable raw materials are kept in the production cycle instead of landfilling or burning. Wood and wooden products can be efficiently separated in waste management, reused and recycled. The so-called wood waste – old furniture, wooden pallets, window and door frames, demolition wood, used lumber, bark and other wood residues can be reused in particleboard production. Particle board manufacturers in the Czech Republic have adopted progressive waste management and currently use 60% of recycled wood into particle boards. A completed life cycle analysis (LCA) of OSB demonstrates that replacing of 50% of natural fibres with recycled wood has significant environmental benefits. The objective is to push furthermore on effective legislation to promote waste material utilization and thus lead to a more sophisticated waste wood collecting.

7.5.2018
doc. Ing. Milan Gaff, Ph.D., Ing. Kamil Trgala, Ph.D., Ing. Tereza Adamová

Wood and the materials on its basis fulfil the requirements of an ever-evolving and accelerating society. In addition to naturally grown wood, wood-based materials are frequently used as a basic material for production of furniture and for building constructions as well. Looking at changes in waste management, a significant shift from the waste to the circular economy can be observed. The valuable raw materials are kept in the production cycle instead of landfilling or burning. Wood and wooden products can be efficiently separated in waste management, reused and recycled. The so-called wood waste – old furniture, wooden pallets, window and door frames, demolition wood, used lumber, bark and other wood residues can be reused in particleboard production. Particle board manufacturers in the Czech Republic have adopted progressive waste management and currently use 60% of recycled wood into particle boards. A completed life cycle analysis (LCA) of OSB demonstrates that replacing of 50% of natural fibres with recycled wood has significant environmental benefits. The objective is to push furthermore on effective legislation to promote waste material utilization and thus lead to a more sophisticated waste wood collecting.

23.4.2018
Ing. Lukáš Velebil, Ing. Jan Včelák, Ph.D., Ing. Kristýna Čápová, Ing. Milan Dvořák

The paper deals with the experimental analysis aimed at function verification of fiber optic sensors (Fiber Bragg Gratings). The sensors are used for mechanical stress measurement in wooden load-bearing structures. Glued laminated timber beam with built-in fiber optic sensor system was mechanically loaded during two bending tests. The data obtained using the fiber optic sensors were compared with the results of reference measurement method and analytical calculation.

26.3.2018
doc. Ing. Radomír Sokolář, Ph.D., VUT FAST Brno, Ústav technologie stavebních hmot a dílců,

Sintering activity (dependence of porosity, flexural strength and firing shrinkage on the firing temperature) of feldspar dust (Casial) which is generated during the milling of potassium feldspar in Halamky quarry was determined. Potassium industrially milled feldspar Z75K13 as a reference material with similar granulometry and mineralogical composition with Casial was used for comparison. More intensive sintering activity showed dry pressed samples based on Casial in comparison with feldspar Z75K13 (about 30 °C lower sintering temperature – 1180 °C). Casial created red body after firing thanks to higher content of Fe2O3.

Složitá rekonstrukce staršího bytového domu
18.12.2017
Ing. Jan Koláček, Ph.D., doc. Ing. Zdeněk Bažant, CSc.

In December of year 2016 has been finished the extensive reconstruction of the multi-family house built in the thirties of last century, located in the district Žabovřesky of the city Brno. Investor with architect desired the modern appearance of interior and facade of the house, which involved a number of difficult renovations and new structures that had to be consulted with structure engineer. The significant steps of the reconstruction of the multi-family house are described in detail in this contribution.

Fall colours in the Eastern Townships in Quebec, Canada © mbruxelle - Fotolia.com
4.12.2017
Dr. Eva Haviarová, Ing. Milan Šimek, Ph.D., Dr. Henry Quesada

In the last two decades, the US hardwood industry has experienced an important increase in their exports to key markets in Southeast Asia, and Western Europe. However, the export to Easter Europe is currently limited. In these emerging economies, production of furniture and many different kinds of wood products are on the rise. Favorable labor costs, progressive design, and available material resources are key factors that sustain the growth of these industries. The forest products industry is also significant consumer of hardwood lumber. Despite the fact that Easter European countries have its own hardwood material resources, the rapid industry growth, increased sustainability practices, and increased demand of high quality material may require the need for additional material sourcing.

Kompozitní výztuž do betonu
18.9.2017
Ing. Miroslav Procházka, Technický a zkušební ústav stavební Praha, s.p.

The composite materials for strengthening/reinforcement a concrete has become the new construction product set up for compulsory verification pursuant to Act No. 22/1997 Coll. (č. 22/1997 Sb.) as amended by Government Ordinance No. 163/2002 Coll. (č. 163/2002 Sb.) as amended by Government Decree No. 312/2005 Coll. and No. 215/2016 Coll (č. 312/2005 Sb. a č. 215/2016 Sb.) This reinforcement exists in several different types, and accordingly, it also has significantly different properties which must be strictly respected in its use.

4.9.2017
Ing. Magdaléna Kociánová, Ing. Vít Černý , Ph.D., prof. ing. Rostislav Drochytka, CSc., MBA

The paper describes the technology of liquefaction and stabilization of soils that are created in the excavation works of engineering networks. Liquefied grout could be used to fill even the less accessible spaces of utility networks. For the re-use of the excavated soil in a liquefied form, is necessary its pre-treatment, which consists in stabilizing by the suitable stabilizing additive. The mixture is furthermore required the liquefaction by using a suitable liquefying additives. Suitable for stabilization and soil liquefaction it seems the use of fly ash, as is mentioned below in the paper.

26.6.2017
Ing. Kamil Binek, doc. Ing. Juraj Žilinský, PhD.

The cause of moisture in the masonry could by different. By old historical buildings is the problem in absence of hydro-insulation, which was made by flat stones or clay backfill. New buildings have a lot defect by application (for example: pipes penetration, join) or wrong design of hydro-insulation, which are the point infiltration of water in to the construction. This problems are made by wrong projection of hydro-insulation in the project. The project does not reflect all influences of the water. But they are also another cases, which can happened like river floods, flood by the neighbour. In those cases it is demanding to dry the building as soon as possible, to protect the property from the mold and return the function of the building. One of the method, which is suitable for this solution is microwave dehumidification, which realize all conditions in one. This aim include also the practice example of the microwave sanitation technique, used by dehumidification masonry, and the positive results.


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