Optimised mix design, possibly including secondary raw mate-rials
The lowest possible concrete content in the structure component without loss of technical performance
Flexible layout design for the longest possible use
Figure 1: Clinker intensity in relation to concrete compressive strength (data collection and scenarios by VDZ).
From clinker efficiency in cement to clinker efficiency in building
Very large quantities of concrete are used to manufacture floor slabs for residential and commercial buildings. It therefore makes sense to further improve clinker efficiency, especially in these applications. On the one hand, as indicated in Fig. 1, this can be achieved by reducing the clinker content in ready-mixed concrete of normal strength (C25 / 30 being the most frequently used strength class in ready-mixed concrete) in a solid ceiling with 0.25 m³ concrete / m² floor slab (Scenario 1b). Alternatively, a higher strength concrete (C45/55) can be used in a hollow core slab as a pre-fabricated element (Scenario 2a) (Fig. 2).
Due to the lower proportion of concrete in the hollow core slab or the pre-stressed element, a similar clinker content per m² of floor slab is achieved despite the higher clinker content in cements for precast concrete. The question for the future is: could clinker-efficient CEM II/C-M cement also be used for applications with high demands on strength development (Scenario 2b)?
Figure 2: Concrete-, cement- and clinker intensity of floor slabs
In the past years, digital fabrication with cement-based materials has aroused major interest in the architecture and construction industry. The research activities in this field have increased exponentially and various sophisticated solutions for concrete 3D printing are being developed worldwide (Fig. 3). Opportunities and challenges for the practical applications of these technologies will need to be discussed with partners all along the value chain. The same applies for example for gradient concrete.
Figure 3: Resource efficient concrete components - An overview of technological approaches