Aus der Erkenntnis resultierend, dass der Portlandzementanteil in einem Ultrahochfesten Beton (UHPC) aufgrund des geringen Wasseranteils nur zu einem geringen Teil hydratisiert und dann nur als inerter Kornbandanteil existiert, wurde in den hier beschriebenen Untersuchungen der Portlandzementanteil reduziert und direkt durch puzzolanische, latenthydraulische bzw. inerte Feinstäube ersetzt. Im Gegensatz zur üblichen UHPC Herstellung mit Silikastaub als Feinststoff zur Lückenfüllung im Bindemittelgefüge wurden hier zur Vermeidung einer zu großen Oberfläche durch den Lückenfüller im Kornband abgestimmte Komponenten eingesetzt. In drei öffentlich geförderten Projekten BMBF OLAF „ Hochleistungsbeton für Alle“, EU „Energy efficient Building H-House“ und BMBF „C3 Carbon Concrete Composite, Basisprojekt B2 Hochleistungsbeton“ wurden diese Kornband- und chemischen Optimierungen entsprechend den jeweiligen Anforderungen durchgeführt. Über die Eigenschaften der hergestellten Betone und die durchgeführten Untersuchungen wird berichtet. Einige Beispiele beschreiben Anwendungsmöglichkeiten der mit diesen Bindemittelcompounds hergestellten UHPC's, wobei die Produktion von Maschinenbetten mit diesen Betonen bereits zur Serienanwendung gehört.
Nanotechnically optimized binders for the production of user-friendly high-performance concrete; part 1
It has been found that, because of the low water content, the Portland cement fraction in ultra high performance concrete (UHPC) is only slightly hydrated and consequently only exists as an inert particle fraction. In the investigations described here the Portland cement content was therefore reduced and directly replaced by pozzolanic, latent-hydraulic or inert fine powders. In contrast to the usual UHPC production with silica fume, which is used as the fine material for filling the voids in the microstructure of the binder, components with coordinated particle size ranges were used here to avoid an excessive surface area caused by the void filler. This optimization of the chemistry and particle size range was carried out to meet the respective requirements in three publicly funded projects: BMBF OLAF “High-performance concrete for all”, EU “Energy efficient Building H-House” and BMBF “C3 Carbon Concrete Composite, high performance concrete B2 base project”. Reactive synthetic oxides, with which additional hydration reactions can be controlled during the dormant phase of Portland cement hydration, were also used. The results were essentially binder compounds that could be mixed homogeneously in a cement plant and then used with the aggregates available in a concrete plant to produce a UHPC that is easy to handle. The additional silos that would otherwise be needed in a concrete plant for storing silica fume and other fine materials for producing UHPC are no longer required as a result of the binder compounds produced in a cement plant. When compared with the usual UHPCs produced with silica fume, the optimized particle size grading with industrial homogenization then means that a concrete can be mixed even in simple mixers. Optimization of the binder compounds leads to an extremely dense microstructure of the binder in the hardened UHPC, which, as a result, is characterized by special properties, such as durability and ASR resistance, even with particularly critical aggregates. There are descriptions of other concrete properties and the associated investigations that were carried out. Some examples describe possible applications of the UHPCs produced with these binder compounds, in which production of engine beds with these concretes has already become a commercial application. There is also an indication of a route to CO2 abatement through the use of less than 50 mass % Portland cement clinker in the binder compounds.