The technical and economic feasibility of an inverted pavement has been proven abroad and in Brazil, but there are still doubts relating to the parameters that may affect the performance of this type of pavement, particularly in Brazil. There is a lack of studies that identify and characterize the variables that are directly related to the structural behaviour of the cement-treated layer and the contribution of each layer (thickness and elastic modulus) to inverted pavement performance as a whole. Furthermore, the main Brazilian specifications allow designers to make most decisions based on their experience, often generating doubts and uncertainties ranging from the design of the structure to the execution of quality control, directly reflecting on the pavement’s service life. Two test sections designed as inverted pavements, which were evaluated in Brazil, are assessed to identify and characterize the variables directly related to the structural behaviour of inverted pavements. In addition, a comparative analysis of the design, materials, construction, and quality control methods for Brazilian and South African inverted pavements is assessed. Both test sections were built based on the same design principles, but have been presented through different structural performances since their implementation in 2001. Each test section was monitored with deflection measurements between 2003 and 2016. In 2017, two inspection pits were opened in each test section. Samples were collected from all layers, and sent to the laboratory. Additionally, the tests carried out in the laboratory and in-situ in both sections during their construction in 2001, requested in the quality control, were also analysed in this study. The test results from the quality control and the test results obtained exclusively for this study (alongside the available literature) were compared and analysed against each other. Based on the analyses and discussions carried out throughout this research, it is possible to conclude that both the thickness and elastic modulus variables of the unbound base and the cement-treated layer played the most important roles in the behaviour of the inverted pavement, besides the support provided to the cement-treated layer by the underlying layer. Furthermore, the difference in the behaviour of both test sections can be linked to these three variables in addition to the constructive techniques adopted. No direct correlations were found for obtaining resilient modulus through CBR, and obtaining CBR values through DCP tests may vary according to the type of soil. The back-calculated modulus are good and reliable indicators of resistance, however, it is essential to apply adjustment factors. Furthermore, it was possible to identify a linear function with R² = 0.845, where ITS varies as a function of USC, according to the tests result carried out in 2001. However, unfortunately, no satisfactory correlations were found between UCS and ITS, UCS and ft, and ITS and ft from the results obtained in 2017. It is possible that these results are due to the specimens being damaged. / Dissertation (MSc (Transportation Engineering))--University of Pretoria, 2021. / Civil Engineering / MSc (Transportation Engineering) / Unrestricted

This thesis deals with the problem of no-cement corundum refractory castables. In the theoretical part, it focuses on NCC refractory and its use, production technology and input raw materials. The second part of the theoretical work deals with MgAl2O4 spinel. The practical part of the thesis then continues in the topic and focuses on cement-free refractory concrete and the influence of MgO content on their properties.

The aim of master's thesis is separation rubidium from cement bypass dust by columns based od hexacyanoferric and resins

The content of the diploma thesis deals with the study of the flexibility and adhesion of cement tile adhesives, which are modified by a polymeric additive. The effects of the quantity and type of redispersible polymer powder used on the properties of the adhesives, in particular on the deformability of adhesives and their adhesion, are monitored. The theoretical part summarizes the basic data concerning classification of the ceramic tiles, information about the adhesives, the processed part concerning the polymer modified adhesives and the effects of the polymeric additives on their properties. The practical part deals primarily with the study of adhesion and flexibility of polymer modified adhesives and study of microstructure of selected materials.

This diploma thesis deals with the preparation of modified tricalcium aluminate phases using sodium ions, and the study of their hydration processes and products. The X-ray diffraction analysis, isothermal calorimetry, laser diffraction, and scanning electron microscopy with energy dispersion analysis were used to solve this task. The preparation of modified tricalcium aluminate phases using high temperature methods has been described in the experimental section. Furthermore, the X-ray diffraction analysis was used to determine the purity of the prepared phases and the scanning electron microscopy with energy dispersion analysis was used to define the volume of sodium. Laser diffraction was used to measure a particle size distribution in the individual phases. Subsequently, hydration of the pure phases was performed in an isothermal calorimeter. It was followed by hydration of phases in the presence of different gypsum content and then in the presence of saturated portlandite solution. Hydration of some samples was stopped in order to better understand the hydration process. Hydration products were studied by X-ray diffraction analysis. The obtained results were compared with each other and the influence of sodium ions on both the structure of the prepared phases and the course of hydration and its products has been discussed. The effect of adding different volumes of gypsum and portlandite on the course of hydration of the individual phases was also compared.

Cement-based composite boards reinforced by organic fiber, commonly known as cement fiber boards are universal and environmental material. Nowadays they are commonly used in construction industry in the form of facade facing for ventilated facades, interior and exterior ceilings or as a lost formwork for the bridge constructions. In these ways of using the cement fiber boards are strained mainly perpendicularly to their median plane. Material characteristics for this kind of strain are declared by the manufacturers. This diploma thesis is focused on ways of using the cement fiber boards reinforced by organic fiber as prefabricated, constructional material for interior staircases. In this case, every segment is strained even in its median plane. This way of strain is atypical and is not declared by the manufacturers in the manufacturer's technical sheets. The main goal of the diploma thesis was to experimentally determine the material characteristics in relation to the possibility of using the cement fiber boards reinforced by organic fiber for the construction of interior stairways. Material characteristics were determined by using Czech technical standards and information from professional literature. Testing tools made by 3D printing were used in the measurements. The possibilities of connecting cement fiber boards by mechanical and glued joint were checked out. The trial “stand” from CLT boards was designed for the real testing of single-arm and double-arm staircases. The outcomes of the experimental measurements confirmed the possibility to use the cement fiber boards for interior stairways. It is necessary to support the design of the staircase by static calculations and to respect the design of the dimensions of the individual segments in the implementation.

This Master thesis is focused on characterization of multicompound self-compacting heavy-weight mortars resistant against long lasting influence of ionizing radiation in the underground nuclear waste storage. It examines a specific combination of properties of heavy-weight concretes and self-compacting mortars while considering the ecological and energetic impact of their production, as well as the productibility of partial substitutions that do not have negative impact on material properties. The Experimental part provides a comprehensive overview of composition and properties of self-compacting heavy-weight mortars with varying percentages of cement-to-mortar ratio. Sample properties were evaluated based on mechanical test results, thermal analysis, differential scanning calorimetry, scanning electron microscopy and X-ray diffraction.

The Soil Water Retention Curve (SWRC) of different soils has been researched thoroughly by multiple Geotechnical Engineers. The interpretation of the SWRC for a specific soil leads to the identification of certain properties of the soil. The SWRC typically involves a plot of suction measurements (on a logarithmic scale) against the volumetric water content or degree of saturation of the soil. This project aims to determine a manner in which concrete properties (such as durability, porosity, shrinkage, strength and stiffness) can be estimated through suction measurements. The Dew Point PotentiaMeter (WP4C) apparatus was used to measure the suctions of different concrete mixtures, as well as to derive the water retention curve of concrete. A cement paste study was first conducted to determine whether this apparatus is able to deliver representative results, which it is. It was discovered that the water retention curve of concrete is similar to a bimodal SWRC identified by Geotechnical Engineers. Thereafter, a mortar study was completed to determine if the water retention curves can be used to estimate different concrete properties. Three different porosity tests were investigated during this research study, namely the X-ray test, the Mercury Intrusion Porosimetry (MIP) test and a simple test method described in the durability index testing procedure manual assembled by University of Cape Town, University of the Witwatersrand and CoMSIRU. It was concluded that the MIP test and the simple test method described in the durability index testing procedure manual gave the most comparable results with regards to literature. The shrinkage of the concrete mixture was investigated to determine a relationship between the suctions and the shrinkage of the concrete. Different strength tests of all the concrete mixtures were also investigated, namely the flexural test, the compressive test, the splitting cylinder test and the E-value test (stiffness). It was concluded that there was a definite trend between the suction measurements and the specific concrete properties tested. The water retention curve has the potential to describe various properties of different concrete mixtures. / Dissertation (MEng (Structural Engineering))--University of Pretoria, 2020. / Civil Engineering / MEng (Structural Engineering) / Unrestricted

The content of this diploma thesis is to explore the possibility of utilization of wastes generated in the production of cement-bonded particleboards in terms of their application as secondary raw materials back into the production. At first an attention was focused on a fine-grained waste containing wood particles with cement matrix produced during the final adjustment of boards. Further, fly ash generated from the combustion of wood chips in the biomass boiler is assessed. In the theoretical part the different types of waste generated in the production of cement-bonded particleboards are characterized, including their methods of creation, production, use or disposal of the current and other proposals for utilization in the future. The research papers dealing with applications of various wastes in the production of cement composites with organic fibers were also studied. In the experimental part of the thesis the characteristics of each type of waste generated in the production of cement-bonded particleboards are evaluated using laboratory analyses and their pretreatment methods for another use are designed. Subsequently performed the laboratory verification capabilities of secondary raw materials from wastes in cement-bonded particleboards identifying and evaluating basic physico–mechanical characteristics of boards with modified composition.

The cement boards are commonly used as a filler fir or spruce chips-profit wood. The increasing demands for construction materials forcing technology to develop new types of composite materials using an alternative source of fillers. In this work in the context of theoretical knowledge about the specified fibers in composite systems are discussed properties of cement binder and filler for cement – bonded particleboards and alternative materials. The practical part describes the test methods designed recipes and then made boards of which were carved specimens intended for testing the properties of boards with alternative fillers.