Calcined Clays and Geopolymers for Stabilization of Loam Structures for Plaster and Bricks: Fid-Bau Portal

Calcined Clays and Geopolymers for Stabilization of Loam Structures for Plaster and Bricks

Huenger, Klaus-Juergen / Kurth, David

Loam is a very ecological building material with a great potential. It is found worldwide and completely recyclable. Under dry conditions, loam develops high strength values. However, loam is not moisture-resistant. Permanently acting moisture reduces the strength dramatically. The idea to improve the water resistance of loams is adding materials to the loam with the same basic structure. Therefore, metakaolin, calcined clay, here, so-called metaclay and a specially developed geopolymer were selected. Blends of four different loams with different amounts of these additives were produced and tested. Criteria for an evaluation are the dynamical modulus of elasticity and the water resistance. These studies were supplemented by structural investigations using a light and a scanning electron microscope and XRD. The results are very interesting, and the effects depend strongly on the kind of loam too. Not all additives lead to an improvement of the mechanical properties. Nevertheless, not the samples with the highest mechanical values show the best water resistance behavior. Obviously, a balanced structure between loam and additive particles is necessary. Such structures are not so dense but enough resistant to water to guarantee the positive property of fast water absorption and delivery of natural loams. The service lives of the loam prisms could be increased from certain minutes to several days. The best results are obtained with geopolymer-based materials as an additive. This is not so surprising because both the loam and the geopolymer form aluminosilicate structures during hardening.