Three-phase-foams for foam concrete application

Abstract

Minerally bound foams are used throughout in the building industry for their combination of load bearing capacity and thermal insulation. Nowadays this can be achieved by lightweight concretes, especially with aerated and foam concretes. Blocks made of aerated concrete as well as prefabricated components are well-known. Typically the mechanical properties are enhanced by autoclaved treatment and thus result in high energy consumption. Also, the production of aerated concretes is factory based due to stationary autoclaves and the components are limited in their dimensions. Another category of mineral foams are foam concretes. They are produced by mixing a mortar and aqueous tensides or protein foam. The problem in production is to get a controlled and homogeneous air entry and thin, high strength borders surrounding the air pores. The latter has to be achieved on the basis of a dense packing of the materials within the borders. On a laboratory scale, significantly enhanced foam stability could be achieved and the most stable samples showed no destabilizing effects. The improved handling, workability and reproducibility of the modified foam are also leading to an increased reproducibility of the foam concrete quality. The study of the influence of three-phase-foams on microstructure, phase development and mechanical properties of lightweight concrete will be shown and explained.