From the stone to the lime for Tadelakt: Marrakesh traditional plaster

Tadelakt is the Marrakesh traditional plaster that thanks to its waterproof qualities was used for flooring, ceilings, bathrooms, ponds and water tanks. It is realized using a particular hydraulic lime produced in the outskirts of Marrakesh. The paper investigates the compositional characteristics of this plaster starting from the nature of the original carbonatic stone used for the production of the lime. As a matter of fact, the traditional burning process causes the presence of underburnt fraction that coupled with the silicaticclastic fraction of the original raw material behave as aggregate. Therefore, the lime for Tadelakt is not a simple binder but a ready-to-use material that does not need the addition of any aggregate but only water, and pigments if necessary. Other two distinctive features of this binder are the presence of magnesium hydroxide (brucite) and palygorskite that thanks to their fibrous structure contribute to avoid the formation of shrinkage fractures in the finished product. The whole of these characteristics allow to univocally identify the original lime of Marrakesh and to realize this particular plaster.