An integral design concept for ecological self-compacting concrete

This Thesis addresses an alternative design concept for Self-Compacting Concrete (SCC). SCC is a special type of concrete with superior workability, which flows and compacts in all corners of a formwork just by the influence of gravity. Introduced to the concrete world in the late 1980s, SCC has been enthusiastically received by the researchers and was referred to be "the most revolutionary development in concrete construction for several decades." However, till this day SCC is only hesitantly accepted by the concrete industry. The reasons are analyzed in this thesis. The presented design concept is a packing-based approach which considers the entire particle size span of all solid ingredients from the finest to the coarsest particle. Using continuous geometric packing models, an optimization algorithm was developed, which allows, only by the introduction of some basic material information, to perform a computer-based optimization which can be adapted to its practical needs with only a few experimental steps on mortar scale. Along with the preparation of this new simplified design concept, powders, the most important fraction of SCCs, were analyzed in detail. In particular the relationship between grading (packing) and the water demand were of interest. One of the outcomes is a model about a constant water layer around any sized particle, which allows the prediction of water demands and workability. A further advantage of the mix design is the replaceability of materials which allows for an optimization with the locally available materials, one major request of the industry. Moreover, alternative materials, preferably mineral waste materials can be added to the mix this way. Due to the improvement of packing notably less cement is needed to obtain a certain strength compared to conventionally designed SCCs and the produced SCC possess a remarkable stability. This lowered cement content and the possibility to introduce large amounts of waste materials notably improves the ecological balance sheet of this new type of concrete. The outcome is a new type of SCC with superior workability and a possibly lower cost price than conventional concrete while having less impact on the environment - a true-eco SCC. The ecological assessment is carried out using feasible models beyond the carbon footprint which is typically referred to. In order to strengthen the position of concrete as an ecological and sustainable construction material, two more aspects are investigated. This is the use of encapsulated Phase-Change Materials (PCMs) and the application of a self-cleaning and air-purifying effect on concrete surfaces. Both aspects comprise enormous potential and add new functions to the construction material concrete, which by now is truly a high-tech building material.