El concreto permeable es un concreto especial, el cual permite el paso del agua a través de su estructura gracias al alto porcentaje de vacíos que posee a diferencia del concreto tradicional. Esta cualidad del concreto permeable permite acabar con la falta de permeabilidad en las estructuras tradicionales de concreto evitando las fallas estructurales debido al encharcamiento y escurrimiento del agua. En esta investigación se realizó el diseño de mezcla del concreto permeable con una resistencia de 210 kg/cm2, aplicando el método ACI 522.R para poder aplicarlo como una alternativa de carpeta de rodadura en pavimentos. Para ello se realizaron diferentes diseños de mezcla en laboratorio hasta encontrar el diseño óptimo para obtener una resistencia a la compresión de 210 kg/cm2, el diseño de mezcla elegido contaba con las siguientes características: relación agua/cemento de 0.38, porcentaje de vacíos de 13%, 1.5% de aditivo Superplastificante y 7% de arena. Para validar la investigación se realizó la construcción de un prototipo con el diseño elaborado en laboratorio con un área de 2.00 m2 (1.00m x 2.00m). Al concreto en estado fresco se le analizaron sus características de consistencia, densidad y contenido de vacíos; en el estado endurecido se realizaron los ensayos de compresión, permeabilidad y flexión, además de aplicarle una prueba de carga. Los resultados indicaron que el diseño de mezcla usado en el prototipo con resistencia a la compresión de 261.58 kg/cm2 y permeabilidad de 0.01744 m/s puede usarse como alternativa de superficie de rodadura para un pavimento. / Pervious concrete is a special type of concrete which allows the passage of water through its structure due to its high percentage of voids unlike traditional concrete. This quality of pervious concrete allows to end the lack of permeability in traditional concrete structures thus preventing structural failures due to flooding and water runoff. This research will seek to find a mix design for pervious concrete to apply it as an alternative road surface for pavements. To verify the above, different mix designs were performed in laboratory to find the design that give us a compressive strength of 210 kg/cm2, the chosen design had the following features: water - cement ratio of 0.38, 13% air content, 1.5% additive superplasticizer and 7% of sand. To validate the research, a prototype was built with the chosen mix design, this prototype had an area of 2 m2 (1m x 2m). The fresh concrete was analyzed for its consistency, density, and void percentage; the hardened concrete was analyzed for its compressive strength, permeability and flexural strength, finally the prototype was load tested. The results indicated that the mix design used in the prototype with compressive strength of 261.58 kg/cm2 and a permeability of 0.01744 m/s can be used as an alternative rolling surface for pavements. / Tesis

The thesis summarizes general and up-to-date knowledge of descaling during the continuous production of the hot-rolled steel and proposes further streamlining of this process in industrial production. The first chapter of the thesis deals with the origin, structure and physical properties of the scales. The second chapter describes the principles of descaling by using a high pressure flat water jet. The third chapter introduces the principles of the experimental methods and describes the used laboratory equipment. The fourth chapter summarizes the description of the particular experiments and their evaluation, and thus represents the focus of the dissertation. It is divided into six sections which independently solve predefined objectives of the dissertation. The first section focuses on the height and structure development of the scales on 54SiCr6 and HDT580X steels. It has been proven that the height of the formed scales increases with the time and temperature of the oxidation. The layered nature of the scales was verified at the same time. The second section examines the effect of the nozzle stabilizer on the focussing and distribution of the impact pressure of the nozzle. Experiments have shown that increase of 11 % of an average maximum nozzle pressure can be achieved, depending on the type of nozzle and the length of the stabilizer. The third section deals with the analysis of shadowgraphy images of water jet structures of the nozzles. A script was developed for analysis of these shadowgraphy photos by an adaptive thresholding. The findings are correlated using a regression analysis with an average heat transfer coefficient. It has been reported that most of the standard nozzle configurations produced disintegrated stream of little droplets at the height of the rolled surface. The fourth section focuses on the area of water jet overlap, especially the area of the so-called washout, where the impact pressure of one nozzle is reduced by the nozzle stream of the other. The influence of the pressure change and the mutual displacement of the nozzles is investigated. The analysis showed that the change of pressure did not have any effect on the percentage of reduction of the impact pressure in the area of the washout. It has been shown that if the area of the washout is wide the descaling efficiency in this area may be reduced. The fifth section builds on the previous section and focuses directly on the areas of waterjet overlaps. The influence of the change of rotation and pitch of the nozzles is studied. Experiments have shown that small changes in nozzle pitch do not have a significant impact on impact pressure and heat transfer coefficient. The effect of nozzle rotation, on the other hand, was a significant factor for the efficiency and homogeneity of the descaling of the surface. The last section deals with the effect of the rolling speed on the heat transfer coefficient in the descaling process. The regression model has shown that with a higher rolling speed there is a reduction in the average heat transfer coefficient. Conclusion summarizes the results of the dissertation and proposes which findings can be used in the industry to make the descaling process more effective.