At the invitation of the Cuban Central University Marta Abreu in Santa Clara, Prof. Middendorf gave a keynote lecture at the International Conference Sustainable Production And Use of Cement and Concrete with the topic: Eco-friendly ultra-high performance concretes - A contradiction?

In the lecture in front of about 150 international participants, which was prepared together with Ms. Cristin Umbach (M.Sc.), Prof. Middendorf presented the principles for the production of ultra-high-performance concretes and then showed that high-performance properties can also be achieved with any Portland cements, taking into account packing density and extremely low water/binder values. By substituting up to 50 wt.% of the Portland cement with calcined clays, it is still possible to produce concretes with compressive strengths up to 130 MPa. Currently, the durability of these environmentally friendly concretes, especially against seawater attack, is being investigated at the department.