Influence of chemical hydrophobizing agents on moisture exchange between pores of sandstone and surroundings

V článku je zhodnocen vliv vybraných typů chemických hydrofobizačních prostředků na dynamiku výměny vlhkosti mezi póry pískovce z lokality Božanov a okolním prostředím. Experiment, jehož výsledky jsou v příspěvku prezentovány, byl založen na hodnocení dynamiky nasákání a odparu vody ze vzorků kamene bez ošetření a po aplikaci hydrofobizačního prostředku. Byly zjištěny významné rozdíly v interakci s vodou u horniny ošetřené látkami na bázi siloxanů a látkou na bázi rozpouštědla s obsahem nanočástic.The paper deals with influence of selected types of chemical hydrophobizing agents on the dynamics of moisture exchange between pores of sandstone from the locality of Bozanov and surroundings. The experiment, whose results are presented, was based on the evaluation of the dynamics of water absorption and evaporation on stone samples without treatment and after application of hydrophobizing agents. Significant differences in interaction between the rock and water were detected for samples treated with agents based on siloxanes and nanoparticles

Influence of thermal loading on interaction between the Moravian greywacke and water

V příspěvku jsou prezentovány výsledky experimentu, zaměřeného na hodnocení dynamiky nasákavosti a odparu vody z pórového systému tzv. moravské droby. Interakce horniny s vodou je zde studována na tepelně neovlivněných horninách a také na horninách vystavených tepelnému namáhání (žíhání) při teplotách 200, 600 a 1000°C. Pozornost je věnována tepelné stabilitě horniny a změnám v interakci horniny s vodou po žíhání.Results of an experiment focused on evaluation of dynamics of water absorption and evaporation from the pore system of the so-called Moravian greywacke are presented in the paper. The interaction between the rock and water has been studied on rock samples before and after their exposure to thermal loading (annealing) at temperatures of 200, 600 and 1000 °C. The attention was paid to thermal stability of the rock and changes in interaction between the rock and water after the rock annealing

Erosion of metals by pulsating water jet

Cilj rada bio je utvrditi eroziju uzrokovanu pulsirajućim vodenim mlazom koji udara o površinu metalnog uzorka. Istražen je utjecaj ponovljenih djelovanja vodenih impulsa i utjecaja brzine (radnog tlaka) na eroziju metalne površine. Analiziran je i raspravljen razvoj erozijskog modela u odnosu na broj djelovanja. Utvrđeno je da se erozija uzrokovana opetovanim djelovanjem vodenih impulsa ​​javlja u tri faze. Faza erozije površine može se odrediti pomoću ponašanja karakteristika površine (kao što su Ra i Rz) s obzirom na broj djelovanja pulsirajućeg vodenog mlaza.The aim of the paper was to determine erosion effects of pulsating water jet impinging the surface of metal sample. The influence of repeated impacts of water pulses and impact velocity (operating pressure) on the erosion of metal surface was investigated. The development of erosion pattern with respect to number of impacts was analysed and discussed. It was found that erosion caused by repeated impacts of water pulses occurs in three stages. The stage of erosion of the surface can be determined by the behaviour of surface characteristics (such as Ra and Rz) with respect to number of impacts of pulsating water jet

Abrasive waterjet (AWJ) titanium tangential turning evaluation

The paper deals with abrasive waterjet titanium tangential turning. Titanium grade 3 with a diameter of 55 mm was used as an experimental material. Technological conditions of turning tests were the same by gradually changing value of traverse speed (vf = 1,5; 3; 4,5; 6; 7,5 mm·min-1). Experiment tests were performed by using continuous abrasive waterjet of pressure p = 400MPa, by rotation n = 60 rpm of workpiece. The abrasive particles (Barton Garnet) were fed to the waterjet in the amount of 0,4 kg·min-1. It was determined that acceleration of traverse speed did not increase the surface profile parameters.Web of Science53454053

Application of image analysis in research into geocomposite materials

The paper concerns possibilities of the image analysis application to the qualitative and quantitative evaluation of structure and texture of geocomposite materials - the noncohesive rocks injected with polyurethane resins. Understanding the relation between the structure and texture and physical mechanical properties of the materials represents one of the ways, how to determine indirectly probable properties and behaviour of geocomposites formed in practical applications

Removal of polyurea spray coatings from the surface of cement concrete by water jet technology

The paper is focused on the removal of polyurea spray coatings from the surface of cement concrete by the water jet technology. A series of experiments was conducted to disintegrate a defined polyurea spray coat layer on the surface of cement concrete tiles using different configurations of the water jet system. The results of these experiments have confirmed that the continuous water jet was highly effective in removing the spray coat, causing no damage to the concrete substrate underneath. The partial experimental results have also indicated that this process can be used to produce an anti-skid finish on polyurea spray coatings applied onto horizontal structures

Determination of grain size distribution of compact granular geo-materials using optical microscopy image analysis

Procedures of image analysis for determination of grain size distribution of compact psammitic rocks and geocomposite materials based on sands grouted with polyurethane resins are presented in the paper. It can be concluded from the experimental results that the image analysis represents an effective tool for assessment of grain size and morphology of compact granular geo-materials. This is a relatively cheap and not time-consuming way of granulometric analysis usable in engineering geology, geotechnics and construction or building-restoration practise

Repair of Concrete footing of high voltage pylon by polyurethane grouting - analysis of grouting effectiveness

The procedure of state estimation of concrete structure of a high voltage pylon footing before and after its repair by polyurethane grouting is presented in the paper. Analysis of the grouting effectiveness was realised on samples taken from inspection core drilling to the structure. The analysis consisted of rough determination of compressive strength of drill core sample, description of deformation behaviour of the specimen under the load, and structural-textural analysis of created geocomposite using method of fluorescence microscopy combined with image analysis

Stavba polyuretanových geokompozitních materiálů - vizualizační a zobrazovací metody

Use of various techniques of optical microscopy combined with image processing and analysis for visualization and imaging of architecture of geocomposite materials with polyurethane binders is presented in the paper

Study of kerfs induced by laser beam in rocks by image analysis

Use of the image analysis system LUCIA DI for the classification and quantification of kerfs after coherent laser beam interaction with rocks is the main object of this paper