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Conventional concrete is a poor insulating material but has good thermal mass, while lightweight concrete provides good insulation at the price of thermal mass. Precast concrete wall systems have not been widely used in residential homes due to poor thermal and acoustic performance, despite being high quality products that are easy to construct. The variable density concrete panel was designed to combine good thermal storage, insulation and high quality precast concrete. It is produced from a single concrete mix which is vibrated to get a lightweight top layer and a normal/heavyweight bottom layer. The lightweight layer is the wall exterior, having low thermal conductivity providing good thermal insulation while the normal/heavyweight layer is the dense wall interior, having high specific heat to provide good thermal mass and sufficient strength for construction handling and to withstand service loads. The intention of this research was to estimate the hardened performance; that is the structural, serviceability and durability performance of the variable density concrete panel. Further developments to the mix design were made where the fresh properties were measured and thermal performance estimated on hardened specimens. Most of the major technical concerns were proved not being as severe as first thought, making the production of variable density concrete panels promising. To ensure that the variable density concrete would stratify, the concrete mix had to have defined fresh properties. Defined rheological ranges gave a good indication of the stratification potential, but the degree of stratification was also found to be dependent on the intensity and time of vibration. Slump flow had to be within a certain range to achieve good stratification but this alone did not guarantee stratification. Variable density concrete was found to have adequate strength capacity both in axial compression and in tension for likely service loads but the strength required to withstand handling loads at early ages was not assessed. The strength of the variable density concrete was found to be affected by several factors such as; degree of stratification, relative strength and thickness of the layers, curing environment and amount of defects. As the stratification of the concrete increased the thermal insulation improved whereas the strength decreased. Warping was found not to significantly affect the serviceability of panels despite differential shrinkage within the element. The amount of warping was mainly related to the degree of stratification. Warping decreased with better stratification as more stress and strain was relieved in the lightweight layer. The lightweight concrete was significantly weaker as well as being less stiff than the structural concrete and therefore creeps to follow the structural concrete. The thermal properties aimed for were generally not reached, but these mixes were not designed to optimise the thermal performance and were tested before the concrete was fully dried. This increased thermal conductivity and therefore reduced the measured R-values. Stratified concrete had good absorption resistance, poor permeability properties and was highly porous. If the concrete was over-vibrated it tended to have a rough surface finish that would require a coating. Delamination of the panels was not assessed in this research but is a likely mode of failure.

Das Bauwesen steht in den kommenden Jahren vor der Herausforderung, für eine steigende Weltbevölkerung Habitate und Infrastruktursysteme zu errichten – unter Berücksichtigung abnehmenden Ressourcenvorkommens. Dies erfordert die Erforschung und Entwicklung neuer, innovativer Leichtbautechnologien für die Baubranche, die auf ein möglichst leichtes Bauen, die Minimierung des Verbrauchs an fossil erzeugter Energie sowie eine recyclinggerechte Bauweise abzielen [1]. Eine Möglichkeit im Bereich des Bauens mit Beton ist die von Werner Sobek entwickelte Technologie des Gradientenbetons. Dieser technologische Ansatz befasst sich erstmalig mit der Optimierung des Bauteilinnenraums und verfolgt das Ziel, die im Bauteil vorherrschenden Spannungsfelder durch die gezielte Platzierung von Hohlräumen zu homogenisieren. Dies ermöglicht die Herstellung von gewichtsminimalen, sortenrein rezyklierbaren und multifunktionalen Bauteilen aus Beton. [Aus: Einführung und Zielsetzung] / For years to come, the construction industry will be faced with the challenge of building habitats and infrastructure systems for an increasing world population – with regard to dwindling resources. This requires the research and development of new, innovative lightweight-construction technologies for the building sector that aim at constructions that are as light as possible, minimize the consumption of fossil-based energy and are designed for recycling [1]. One possibility to meet these requirements in the field of concrete construction is the technology of graded concrete which was invented by Werner Sobek. This technological approach focuses for the first time on the optimisation of the component’s interior and pursues the goal of homogenizing the stress fields prevailing in the component through the targeted placement of cavities. This enables the production of minimal-weight, mono-material and multifunctional components. [Off: Introduction and objectives]

Yes / This paper investigates the effect of cement based grout rheology on the injection process through coarse aggregate for producing preplaced aggregate concrete. Four different sands were used in the grout production at different water-cement ratios and cement-sand ratios. Superplasticiers and pulverised fuel ash were also employed in the grout production. Coarse aggregate of known weight was compacted into 150 mm cubic forms, and then the grout was injected through a plastic pipe under self weight into the stone ‘skeleton’. It has been found that there are threshold values of the rheological parameters beyond which full injection is not possible. In particular, all grout mixes with and without additives and admixtures exhibited the same yield stress threshold value for full injection, whereas the threshold values for other rheological properties including the grout plastic viscosity, flow time and speed were different according to the materials added to the mix.

The master's thesis is elaborated on the basis of the project of the Sport and Health Center Olomouc. The project consists of two main buildings – the object of NH Hotel and the Sports Center Omega. The hotel also includes a conference center with three conference halls and covered parking. The object of Omega Sports Center is composed of sports halls for squash, badminton and tennis, along with changing rooms, wellness area and operational background of the object itself. The sports center also incorporates outdoor tennis courts and an underground tunnel connecting the Omega center and the NH Hotel. This thesis deals with the civil technological project of the building site and involves mainly the technical report of civil technological project, the study of realization of the main technological stages of the building object, the project of organization of construction, time schedule of aforementioned two main buildings, the technological standard with test and execution plans for the execution of underground construction by the impermeable concrete technology and for execution of variant solution of tennis hall roofing. Further, a comparison of the alternative roofing technology with current used roofing technology is performed, including the drawing documentation of new roofing alternative.