A New Generation of Sustainable Structural Concretes – Design Approach and Material Properties

Sustainable concretes, also termed eco-concretes or green concretes, produced with a significantly reduced cement content provide a promising alternative for improving concrete sustainability without using supplementary cementitious materials, such as fly ash or slag. However, the production of such eco-concretes is a challenge in view of concrete technology and concrete properties. In particular, new design concepts as well as new admixtures have to be developed and applied to produce concretes with a cement clinker content of approx. 100 kg/m3 while keeping the concrete performance on a level similar to ordinary structural concrete of today. To evaluate the sustainability of these new types of concretes not only the very low ecological impact due to the composition may be regarded, but in addition also their technical performance, i.e. their mechanical, physical and chemical properties have to be taken into consideration. This contribution firstly gives an overview on sustainable approaches for concrete structures, further introduces the Building Material Sustainability Potential as an index, which is applied in combination with the service life prediction for cement-reduced concretes using full probabilistic methods. The composition of these particular structural concretes is discussed and related test results for their performance are presented. The contribution closes with an introduction to graded concrete structures as an innovative approach for the improvement of concrete sustainability on a structural level and presents testing results for mechanical and durability properties of graded bending beams. The paper at hand extends the information given in [1] by looking more closely at the performance of graded concrete structures and here in particular by considering concretes produced from intermixing two concrete types (i.e. eco-concrete and UHPC) in the fresh state