Jiří Zach

Development of Masonry Components Protected against Moisture

During construction process and life, a number of negative influences can have effect on masonry structures; moisture, which is undesirable in the masonry, can be one of such influences. The lower area of the masonry (plinth walling) is strained the most by the moisture. The paper deals with potential reduction of the effect of moisture in places, where the masonry structure is founded, through hydrophobization of walling units. Such solution of the issue of protection of the building structure against the influence of humidity should not have negative effect on the resulting masonry parameters, particularly not on the potential application of surface treatment materials. The collective influence of the surface treatment materials, consisting usually of plaster, and the actual masonry should be ensured.

NDT of LWC with Expanded Clay

Nowadays, light-weight concrete (lwc) is increasingly used in construction, namely lwc with aggregates of expanded clay type called Liapor. It is often necessary to perform tests for the characteristics of cast-in-place concrete during building construction as well as after the construction. One of the ways to control the quality of LWC in a structure is using non-destructive testing (NDT) methods. For compressive strength, there are reflective rebound methods and ultrasonic pulse method (UPM) which may also be used for determination of dynamic modulus of elasticity. This paper presents the results of NDT of LWC with expanded clay using above the mentioned methods and as well as the associated calibration relations. A comparison of conversion coefficients obtained from modulus of elasticity tests on normal-weight concrete (NWC) and LWC is also provided. The developed calibration relations resulted in a high degree of correlation between the NDT results and the results of compression tests on concrete specimens.

Development of Concretes with Resistance to High Temperatures in the Czech Republic and Surrounding European Countries

The resistance of concrete constructions to high temperatures at present is a much monitored issue for many scientific teams and experts in the stated area. This fact is mainly caused by fatal consequences originating in the case when concrete constructions are loaded by the effect of fire and consequent loss of their load-bearing capacity, for the population and the environment of our planet, in which we live in. The development of society goes hand in hand with the development of new building materials and as a consequence the requirements for building constructions increase which bring about extraordinary strict regulations in the area of fire safety. So, many high, non-traditional or specific constructions originate, e.g. nuclear power plants due to permanently higher demand for transport linkage and many tunnels have originated between European countries as a result. Unfortunately, in this relation the threat of terrorist attacks increases and unexpected natural disasters which also threaten the stability of the mentioned constructions. The objective of the article is to familiarize readers with the results of research concerning the improvement of the resistance of the concrete to high temperatures originated during fire instances.

Development and Study of the Possibilities to Use Natural Materials for Thermal-Insulation Systems of ETICS

Thermal insulation systems of ETICS are now mostly solved in the building industry, whether in terms of insulating the structures, choices of materials and subsequent recycling after the end of their life period. From the environmental point of view and also in the perspective of sustainable development, it is essential to look for other suitable material bases which relate only to easily renewable sources of raw materials or to industrial wastes which have long been available in sufficient quantity and quality. It is important that production of the insulation systems is energetically efficient modest in terms of manufacturing facilities. The aim of this paper is to verify the possibility of using natural insulation materials for thermal insulation systems ETICS. This paper describes the results of studies of key properties of insulations based on industrial hemp and flax and the results of computational simulations of the behavior of these insulations incorporated in the real systems ETICS.

Development of Light-Weight Concrete with Utilization of Foam Glass Based Aggregate

The use of material based on by-products and easily renewable materials in modern building structures is today’s preferred route for long-term sustainable construction and this method of construction also respects the principles of key documents, such as the Kyoto Protocol/ Paris Climate Agreements, Agenda 20-20-20, etc. In the field of light concrete (LC), the long-term effort is to effectively reduce the bulk density to a level where the concrete will still exhibit sufficient mechanical properties, so it would be possible to use it as construction material in building structure and at the same time will exhibit a sufficiently low thermal conductivity for the construction to fulfil strict requirements in the field of thermal protection of building without the need for additional thermal insulation layers. The paper describes the results of the research in the utilization of light-weight aggregate based on foam glass in conjunction with by-product based fibers for the development of light-weight porous concrete with very low density and thermal conductivity.

Development of New Advanced Plasters with Waste Fibers Content

The paper deals with the possibilities of using secondary raw materials in the development of new advanced lightweight plasters. It was about fibers from recycled waste materials (waste paper, PET bottles, tyres) and recycled insulation (stone wool). The aim of adding fibers to these lightweight building materials was improvement of mechanical properties, improvement thermal insulation properties and reduction of crack sensitivity. It can be stated, based on the evaluation of the selected measurements, that both types of cellulose fibers and fibers from recycled tyres had positive influence on the mechanical properties, namely in the case of compressive strength. From the point of view of thermal insulating properties, it can be said that only 2 types of fibers have reduced the value of the thermal conductivity. They were mixtures with stone fibers and with recycled tyres fibers. Both of these mixtures also showed the lowest average values of bulk density. Based on the carried out research works can be it concluded that the use of recycled tyres fibers show as optimal.

Study of Hydrophobic Modification of Ceramic Elements

The protection of building structures and elements from the effects of moisture is currently a topical and discussed topic and this issue is also related to development of hydrophobized ceramic masonry elements with reduced water absorption.The quality and efficiency of the hydrophobic treatment is assessed primarily by monitoring the capillary absorption of the hydrophobized ceramic body and reducing the capillary conductivity (reducing the capillary elevation of moisture).The paper focuses on the more detailed physical study of the hydrophobic treatment of ceramic masonry blocks using laboratory methods, in particular the measurement of the contact angle and surface energy. With these measurements, it is possible to precisely specify the surface properties of individual ceramic masonry elements treated by hydrophobic treatment and thus accurately express the quality of the surface treatment. Based on the results was determined the dependence between capillary absorption and surface energy.

Effect of Plasticizing Admixtures on the Development of Hydration Temperatures and the Properties of Cement Pastes

The hydration of cement is a very intricate process. A great amount of heat is generated during the reaction, which requires close monitoring especially in large concrete members. Modified cement pastes are simpler systems and can be easily used to observe the effect of plasticizing admixtures on the development of temperatures during cement hydration as well as its rheology and mechanical properties. Knowledge of the development of hydration temperatures can be of assistance in deliberate regulation of cement hydration and the generation of hydration heat. The paper describes what influence different amounts of different plasticizers have on the properties of cement pastes, with added focus on the development of their hydration temperatures, rheology and compressive strength.

Computational Simulation of Behaviour of Developed Thermal Insulation Plaster Based on Silicates with the Use of Program WUFI 2D

The investigation of the hygrothermal behavior of advanced silica materials, which are today in ever increasing demand during the reconstruction of building envelopes, is an important point of research. For determining the moisture balance in building structures, the Glaser method is most frequently used to day which, however, considers during calculations water diffusion only in stationary state at simplified marginal conditions; it does not take into account the moisture transport in the capillary system of the material structure, nor the sorption properties of the material. The goal of the research is therefore to gain deeper knowledge of the way heat and moisture transport through the pore structure of these silica materials. The paper describes verification of efficacy of thermal insulation and rehabilitation silicate plastering. Based on experiences from previously research and their results were chosen 2 developed plasters for computational simulation of their behavior in the case of detail of window jamb. One type of developed plastering was placed from the site of interior and the second type of plastering was applied from the site of exterior.

Possibilities of Using Recycled Concrete and Silica Binders for Development of Sound Absorbing Concrete

With development and reconstruction of traffic routes there has recently been an increased need for noise reduction measures, out of which the most effective one appears to be the construction of noise barriers that prevent sound propagation from its source and (in case of sound absorbing barriers) absorb sound and thus reduce the noise load near the sound source (around a traffic route). The manufacturing of noise barriers often enables the use of secondary raw materials and thus to reduce the energy and material costs of their production as well as decrease the environmental impact. An interesting option is the use of recycled concrete that is suitable for production of concrete with open structure to be used in the absorber layer of a sound barrier and can even be used in the structural layer as well. The paper describes the possibilities of using recycled concrete in the production of sound absorbing barriers with a high degree of sound absorption.