Radka Pernicová

Thermophysical properties of hydrophobised lime plaster – Experimental analysis of moisture effect

Lime plasters are the most popular finishing materials in renewal of historical buildings and culture monuments. Because of their limited durability, new materials and design solutions are investigated in order to improve plasters performance in harmful environmental conditions. For the practical use, the plasters mechanical resistivity and the compatibility with substrate are the most decisive material parameters. However, also plasters hygric and thermal parameters affecting the overall hygrothermal function of the renovated structures are of the particular importance. On this account, the effect of moisture content on the thermophysical properties of a newly designed lime plasters containing hydrophobic admixture is analysed in the paper. For the comparative purposes, the reference lime and cement-lime plasters are tested as well. Basic characterization of the tested materials is done using bulk density, matrix density, and porosity measurements. Thermal conductivity and volumetric heat capacity in the...

The influence of inner hydrophobisation on water transport properties of modified lime plasters

The effect of hydrophobic agent admixture on water vapour and liquid water transport properties of newly designed lime plasters is analysed in the paper. The major part of physico - chemical building deterioration is related to the penetration of moisture and soluble salts into the building structure. For that reason, the modified lime plasters were in the broad range of basic material properties tested. From the quantitative point of view, the measured results clearly demonstrate the big differences in the behaviour of studied materials depending on applied modifying admixtures. From the practical point of view, plaster made of lime hydrate, metakaolin, zinc stearate and air-entraining agent can be recommended for renovation purposes. The accessed material parameters will be used as input data for computational modelling of moisture transport in this type of porous building materials and will be stored in material database.

Influence of Pozzolana Admixture on Long-Term Chemical Characteristic of Cement Mortars

nfluence of non-flowing model sulphate solution determined for cement mortar with pozzzolana admixture are presented in this paper. In the predetermined time intervals the influence of the aggressive liquid on chemical properties and mineralogical composition was tested. The changes caused by corrosive sulphate environment on the testing specimens were determined in dependence on the different type of cement and used ground clay brick as pozzolana admixture. From the results obtained follows that the additive of ground clay bricks has positively impact on the sulphate resistance.

Shape Characteristics and Granulometry of Recycled Silicon Carbide Waste

The main aim of this paper is determined of properties, especially granulometry, of recycled silicon carbide waste and its possibility of using in new cementitious recipes. Paper is focused on importance of creation of grain curves and on relationship between silicon carbide and compounds in concrete matrix. Purpose of this research is using waste material and therefore minimalizes of its production and reduces ecological effect on environment by its recycling. Set of granulometry measurements of each recycled materials were done as well as its grain characteristic. The End of work includes the evaluation of the possible use of SiC waste for cement mixtures.

Influence of Hydrophobic Agent on Rheological Behavior of Historical Plaster. Part 1: Initial Hardening Time

The influence of time on rheological properties of modified lime plaster is analyzed in this paper. Effect of composition of mixture is examined as well. Especially changes of paste due to hydrophobic and pozzolanic admixture. Main aim of rheological test is determination of flow curves, obtained by applying a succession of constant strain rates for short times. Base on performed experiments, it can be concluded that hydrophobic admixture eliminated influence of pozzolana. Also both time and temperature caused significant changes in rheological properties. Increasing values decreases the flow characteristic of the plaster. A comparative measurement with pure lime plaster was done as well.

Technology of 3D Print in Field of Renovation of Architectural Structures and Historical Buildings

The article analyzes possibilities of using additive manufacturing in the building industry, especially in the field of reconstruction of building structures. On concrete examples, growing potential and future perspective of the additive manufacturing technology are demonstrated in the text. There are also presented cases of reconstructions, especially in combination with the 3D scanning method. At other points, the basic principles of this technology are presented, its advantages over conventional technological procedures and the possibility of application of special concrete as a primary material in the context of 3D printing and the construction industry.

Influence of Hydrophobic Agent on Rheological Behavior of Historical Plaster. Part 2: External Temperature

In a previous study, we presented new method measurement rheological properties of hydrophobized plaster in dependence of hardening time. Influence of external temperature on pozzolana plaster is analyzed in this paper, especially plasticity and workability of paste. Main aim of rheological test is determination of flow curves, obtained by applying a succession of constant strain rates for short times at the temperature 10°C and 30°C. Base on the performed experiments, it can be concluded that the temperature have very significant influence on rheological properties of plasters. With an increase in temperature, the application time of the mixture is shorter, from hour to minutes. A comparative measurement with pure lime plaster was done as well.

Measurement of Chloride Permeability in UHPC by Accelerated Method

The chloride permeability of concrete (UHPC) was evaluated by means of the Rapid chloride permeation test and and standard difusion test. The tests are different in the voltage applied for accelerating the transport through the concrete specimen. The permeability strongly depends on quality and curing time of the concrete.

The Influence of Glass Fibers as Dispersed Reinforcement on Hydric Properties of Concrete

In this paper, the effect of different kind of glass fiber on hydric properties of ultra-high performance concrete and normal strength concrete is determined. It was the use several types of micro fine high-dispersible alkali resistant fibers that prevent the formation of shrinkage cracks caused by tensions. Comparative measurements with both concrete without glass fibers are done as well. The main aim of this experimental work is to obtain sufficiently accurate input data for the estimate of durability surface layers of concrete which are connected with water transport and its accompanying effects such as biological degradation, water soluble salt transport or degradation by rainwater absorbing oxides of sulfur and carbon from air.

Resistance of Surface Layers of Concrete against Aggressive Environment

The article deals with the corrosive effects of acids on the selected surface layers of concrete with/ without an epoxy coating. Concrete sample was placed in extreme environments, which represented the 40% sulphuric acid solution. In addition to measuring surface degradation of concrete, this work focused on the depth of acid penetration into the sample. It can be concluded that the long-term effects of aggressive environments severely degrades the concrete surface on the samples causing corrosion of Type II.