Überall in der Planung und Ausführung eines Bauprojekts gibt es Schnittstellen, an denen Festlegungen und Informationen von einem Beteiligten in der Kette zum nächsten weitergegeben werden müssen. So heißt es im DIN Fachbericht 100: „Jeder ist dabei für die Weitergabe der festgelegten Anforderungen zusammen mit etwaigen zusätzlichen Anforderungen an den nächsten in der Reihe bis zum Hersteller verantwortlich.“ Dabei ist die für die Betontechnologen interessante Schnittstelle natürlich die Frage, welche Festlegungen der Tragwerksplaner hinsichtlich der Betonzusammensetzung macht. Und das erfolgt an diversen Stellen, da die Betoneigenschaften direkt von der Zusammensetzung des Betons beeinflusst werden.
Dimensioning meets concrete technology
Everywhere in the planning and execution of a construction project there are interfaces where specifications and information must be passed on from one participant in the chain to the next. Thus it is called in the German DIN technical report 100 “Everyone is responsible thereby for the passing on of the specified requirements together with possible additional requirements to the next in the row up to the manufacturer”. The interface of interest to concrete technologists is of course the question of which specifications the structural engineer makes with regard to the concrete composition. And this is done at various points, since the concrete properties are directly influenced by the composition of the concrete. Components of the concrete composition such as water-cement ratio, certain cements or rock types of the aggregate may and must be specified by the structural engineer in order to plan the strength development or the deformation behaviour of the hardened concrete. The water-cement ratio, the cornerstone of concrete technology, is determined not only by the concrete compressive strength classes but also by the use (exposure classes). It should be noted, however, that, on the one hand, these cements cannot always be used depending on the weather (summer/winter) and, on the other hand, these cements are not always available for logistical reasons. It is not surprising that the aggregate, as the largest part of a cubic meter of concrete in terms of quantity, has an influence. The requirements for the constituents of the concrete composition must of course be made known in the offer phase so that possible effects on the concrete price can be taken into account.