Floor construction is assessed within the thermal field by the heat transfer coefficient and surface temperatures, and in the acoustic field particularly from the point of view of airborne and impact soundproofing. When using ultra-light concrete for the construction of flooring there are unique parameters to consider. Within the contribution, the development occurred of an ultra-light concrete daub that achieved this minimal weight due to an aggregate product based on foam glass. This ultra-light concrete displays a very good ratio of mechanical performance to thermal insulation properties. As a result of these excellent thermal insulation properties, and the design of a concrete daub without joints, the formation of thermal bridges in floor construction can be eliminated.
The article pays attention to the importance of daylight and sun exposure of apartments for public health. The daylight of apartments must be given the same attention as the daylight of workplaces and schools. The way in which the daylight factor Dw (%) of the exterior window plane was introduced into the Czech technical standardization as a criterion is described. The results of a study regarding daylight of living rooms in connection with the limit values of this factor and in connection with the so-called distance angle and window area determined as 1/10 of the floor area of the living room are presented.
Together with the professional journal Podlahy, we have prepared a new series, where the authors get acquainted with the basic standard ČSN 74 4505 Podlahy - Common provisions and subsequently with other standards that are important for the floor area, and also respond to comments from opponents and reviewers. The first part of the series describes the most important provisions of ČSN 74 4505 in an annotated form.
The unfavourable effects of the weather on unprotected wood and timber products can cause changes to the mechanical and chemical properties of the wood, and if unchecked can do irreversible damage. The sheathing of wooden buildings must always be supplemented with surface treatments, and in a large number of cases a contact thermal insulation system is used. The paper presents research focused on the possibility of using a commonly used cement adhesive for bonding thermal insulation to the substrate formed by oriented strand boards. The substrate is provided with several types of penetration coatings or bonding primers and subsequently their influence on the adhesion of the cement adhesive is monitored. The best values were achieved when treating the surface treatment with a modified dispersion with quartz sand. On the other hand, the penetration coating of a mixture of water, nanodispersion of styrene-acrylate copolymer and additives is inappropriate treatment.
Contractors tend to ignore design solutions to reduce the cost of construction. Change of materials, absence of building elements, adjustment of layer composition, application of cheaper alternatives – these are common situations in construction practice. In certain cases, these modifications are without consequences, but in such a situation it is necessary, among other things, to take into account the laws of physics. This article deals with the case in which the structure was replaced – instead of the reinforced concrete ceiling slab, the contractor chose a wooden structure. Wood has significantly different properties than reinforced concrete, so it is necessary to take into account several aspects such as statis, thermo-technical properties and last but not least – with whitch this article deals with – moisture conditions in the structure. The relationship of wood and moisture is specific, the article assesses a specific case of such a structure, lists the possible consequences and finally suggests the most appropriate solution – adjusting the composition of this particular ceiling structure to meet the requirements.
This paper will focus on the question of how we can work with brownfields and it will deal with tools that enable the revitalization and rehabilitation projects in the area. Tools can be divided, for example in terms of spatial planning and urban design, from an environmental perspective, from the perspective of cultural heritage protection and from the perspective of investment opportunities. The result is that the issue of brownfields is handled by numerous institutions and instruments. The aim of this paper is to identify, classify and analyze these instruments. Paper will study instruments from other countries with long-term experience with this issue (eg. France, Great Britain, USA, Germany, Denmark) and analyse the feasibility of their implementation in the Czech Republic and their contribution. Because this theme is a very complex one, this paper is mainly focused on urban planning tools, economic tools (incentive and penalty) and building tools (designed to uphold the intentions of the municipality or the state by building mainly transport and technical infrastructure).
The Architecture and Urban Planning Committee of Protected Landscape Areas in Central Bohemia Region has to deal with low-suitable new family houses architecture design very often. The recommendations for buildings were written to preserve typical architecture form. Due to the passive standards coming be ordinary used in family house design, Administration of the Krivoklatsko PLA initiated the cooperation with Faculty of Civil Engineering CTU in Prague to try find new design for Krivoklatsko PLA. Architecture and Building Engineering students worked out design of new family houses as their Bachelor projects. The goal of this paper is to present student projects as an inspiration for builders and evaluate the usage of new shapes and materials in the design suitability context.
The concept of sustainable development is becoming increasingly popular worldwide. The intensive debate on sustainability issues in the construction industry has led to the development and implementation of various systems for defining and assessing the sustainability of buildings around the world. Concrete is one of the most important and useful materials in the construction sector, which, unfortunately, has an adverse impact on the environment, it is evident that correct procedures for designing concrete structures need to be created. In this paper is an indicator expressing quality, with regard to sustainability, is determined using information on concrete performance characteristics, service life and environmental impact, enabling the quantification and comparison of various cases.
The present paper deals with the measurement of the thickness of the coating on wood using the ultrasonic method, which is based on the measurement of the ultrasonic pulse passage time through the layer. One of the biggest advantages of this method is non-destructive measurement, which allows online quality control during operation, eg when checking paint thickness on window or door frames. During the experiment, the deviations of the coating thickness measured by the destructive and non-destructive method were recorded, however, these deviations were in most cases smaller than the inaccuracy of the optical microscope measurements. The results clearly showed that the accuracy of the described method is sufficient and can therefore be used to measure the thickness of the coating on porous and diamagnetic materials such as wood.
The newly developed jointing grout is designed not only for normal conditions, but also for environments with higher chemical stress. For this reason, one of the key endpoints was also a chemical resistance of the grout. The jointing grout is based on a polymer basis, in particular with epoxide binder used, and also hazardous wastes are used as fillers. As is well known, the epoxy thermosets are very resistant to inorganic acid solutions. However, they can be easily degraded by the action of organic solutions. Within this fact, the aggressive environments and their concentrations were selected and their influence on the developed grout was assessed. Specifically, the effect of action of 60% sulfuric acid, then the influence of the action of vapours of this acid (at a concentration of 96%) and immersion of 10% acetic acid solution were assessed. After exposure to these aggressive substances, the visual changes of the samples were assessed primarily. Colour change, blistering, cracking, flocculation, gloss change, etc. were monitoring. The influence on microstructure, change of bulk density and flexural and compressive strength of the polymer jointing grout materials was studied.
White tanks are structures which, in addition to the load-bearing function, must also have the function of watertightness. Watertight of the concrete is ensured by adherence to design, production and technological measures. The width of the early-age cracks that former in the structure is controlled by the reinforcement. During construction, however, joints (expansion, construction and control) are created in the structure, which must also be watertight. The joints are the most sensitive place of the white tank and therefore the most leaks are created at the point of the joints. The correct choice of the joint sealing system is the basis for the design of the watertight joint. The paper deals with the description of various joint seal and pipes through of the white tank.
One of the main characteristics in the concreting of massive, waterproof and dam structures is the prediction of crack formation. This prediction is connected with the understanding of mechanism hydratation temperatures development in concrete that affects in particular the selected parts of binder. Suitable combination of cement and mineral admixtures, as well as the usage of shrinkage reducing admixtures appears to be an effective tool for influencing the dynamics of development and maximum values of hydration temperatures. Appropriate selection of the concrete formulation can significantly extend the mentioned structures lifetime.
The article is focused to a monitoring of influence of different mineral admixtures on influence of volume changes of cement pastes. Furthermore, in this article was monitored connection between volume changes and hydratation temperatures development of cement pastes. With the target of minimalization both these phenomena were used shrinkage reducing admixture.
The elementary aim of the described research is to prove the necessity of creating an additional impermeable layer acting as moisture insulation of historical structures by means of undercutting technology. From a technological point of view and also based on known research, it is obvious that this technology is one of the most effective remediation methods. Unfortunately, the use of this technology is from the point of view of Regional Monuments Authorities, which, due to adherence to the uncompromising Venetian Charter, is considerably limited, because, despite considerable efficiency, this technology disrupts the integrity of historical vertical structures. The methodology of research into undercutting technology consists in verifying and demonstrating the effectiveness of this technology in various historical buildings and recording individual moisture values in situ before and after the implementation of the technology. The results measured in this way should objectively prove the necessity of using the technology of undercutting masonry as a remediation method of wet historical structures, provided that this does not compromise the statics of the object and this intervention is necessary.
The mass construction of apartment buildings using the technology of large-format prefabricated prefabricated elements in the former Czechoslovakia took about 40 years. The lifetime of these buildings is approaching their planned value. A common problem of prefabricated buildings is the creation of new openings in load-bearing structures without prior expert appreciation. The important details of the joints of the support elements have changed not only between the individual assemblies, but also during the development of the particular assembly. The article describes some problems of load-bearing structures of prefabricated buildings, which designers have to consider in their assessment.
This paper is a theoretical research of semi-rigid timber connections using modern fasteners Rothoblaas Alumidi. These connectors allow for semi-rigid behaviour. The aim of the research is the examination of the real behaviour of structural connections with real constants of rigidity. The rotational stiffness is calculated according to [1] and it is verified by the method of deflection of virtual bending moment. The results of the numerical calculation will be confronted with experimental verification of the connections. Concurrently with the experiment, the axial loaded grip nails will be examined in order to determine the value of slip modulus.
The construction of precast hous consists of prefabricated concrete walls and floor slabs. These elements through joints form rigid spatial (so-called box) load-bearing system. The prefbricated elements of this system were designed for certain layout and static possibilities of the panel system. All additional interventions in the load-bearing structure must be thoroughly investigated. If necessary, it is also necessary to propose a suitable way of strengthening the weakened parts of the load-bearing system.
This article is focused on current situation in preparation of new generation of European standard for design of concrete structures prEN 1992-1-1. This article deals with main features and development in design principles involved in new standard. In these days there is available the 4th draft of standard for comments of national authorities and experts. The final draft of prEN 1992-1-1 should be finished this year (2020) and provided to formal vote in CEN.
This is a case study of a multifamily residential building that has been environmentally assessed in terms of greenhouse gas (GHG) production using a simplified life cycle assessment (LCA) method. The results of total GHG emissions were compared to the emission limit value, which was set based on the climate objectives of the Paris Agreement and the scientific report The Emissions Gap Report. In response to the non-compliance with the emission limit, a number of emission-saving measures have been proposed and have been suitably designed into variants meeting the emission requirement.
The paper briefly specifies the possibilities of computational estimates of the magnitude of accidental leakage of gases and liquids from tanks, pipelines and equipment under pressure, the rate of evaporation of not boling liquid from a pool created by the discharge and adiabatic flashing vapor of liquefied gas during its discharge into the environment. It presents three examples of these calculations using SW Excel. The seriousness of the issue is demonstrated by the selection of statistics on fires and explosions in the Czech Republic for the period 2017–2018 and by a picture of a prefab house in Prešov after the gas explosion in December 2019, which attracted a lot of attention from the general public. With regard to the growth trends of production and consumption of dangerous chemicals and preparations in the world, EU and the Czech Republic, the conclusion of the article emphasizes the need for further development of preventive measures to prevent accidents, including methods of risk analysis.
