Eco-friendly concretes with reduced water and cement content - Mix design principles and application in practice

In several test series the fresh and hardened concrete properties of water and cement reduced concretes were investigated, especially the workability, the strength development, the design relevant mechanical properties as well as durability aspects like carbonation. It was shown that concretes with cement contents lower than 125 kg/m3 were able to meet the usual required workability, strength (app. 40 MPa) and mechanical properties. The carbonation depth of concretes with 150-175 kg/m3 of cement was equal or lower than the depth of the conventional reference concretes for exterior structures. The ecological advantages were identified, using the environmental performance evaluation. A reduction up to 50% in environmental impact compared with the conventional concrete and a reduction of more than 65% by using blast furnace cement was calculated. The application in practice was verified conducting full-scale tests in a precast and ready-mix concrete plant. The special requirements on workability and early strength were fulfilled with a cement content of 150 kg/m3.