El Amrani et al., JMES, 2018, 9 (3), pp. 754-762 754 J. Mater. Environ. Sci., 2018, Volume 9, Issue 3 Page 754-762 https://doi.org/10.26872/jmes.2018.9.3.83 http://www.jmaterenvironsci.com Journal of Materials and Environmental Sciences ISSN : 2028;2508 CODEN : JMESCN Copyright © 2018, University of Mohammed Premier Oujda Morocco 1. Introduction Used since the Neolithic age, lime is a natural material produced by burning limestone. It is a binder which, mixed with water and possibly other natural products like sand and volcanic materials, makes it possible to obtain a mortar, a product that can be utilized with many different functions (to connect bricks and stones of a masonry, to plaster, as sealing etc.). A particular use of this material is Tadelakt, a finishing technique for supports (wall, floor, ceiling, ...). This traditional plaster consists of lime, water, black soap and often mineral pigments. The technique was created and developed in the Marrakesh region thanks to the very special lime produced in that territory. The knowledge of this artisanal product (raw materials, history, manufacturing process, etc.), its uses and interactions with the environment, will makes it possible to improve its production process and quality of the finished product promoting this ancestral heritage in the field of construction. 2. The Tadelakt: history Tadelakt is a traditional Marrakesh lime plaster that thanks to its waterproof qualities and resistance to water, was used for flooring (dess), ceilings, arches and domes and it is the traditional plaster for water tanks, bathrooms, basins, etc. [1-2] (Fig.1). Tadelakt was known in the region of Marrakesh and it can be compared to marmorino, which is found in many Mediterranean countries. Nevertheless, it is much more than a traditional plaster, it is the identity, the symbol and the culture of a region [3]. This material and technique take the name from the Arabic name dellek meaning “rubbing”. It requires lime, black soap, a polishing stone and other tools, and can be realized only by experienced craftsmen, the “maalems”, who have inherited the expertise which remains the key factor to achieve a good finished artefact. The history of this material goes back to the 12 th century, in the Almoravid (1021-1147) and Almohad dynasties (1147-1262). From the stone to the lime for Tadelakt: Marrakesh traditional plaster A. El Amrani 1 , C. Polidoro 2* , M. Ibnoussina 1 , F. Fratini 3 , S. Rescic 3 , A. Rattazzi 2 , D. Magrini 3 1 Université Cadi Ayyad, Faculté des Sciences Semlalia, avenue Prince My Abdellah, BP 2390, Marrakech, Maroc. 2 La Banca della Calce srl, Via Francesco Albani, 1/3, 40128, Bologna, Italy. 3 Institute for Conservation and Valorization of Cultural Heritage, National Research Council, Via Madonna del Piano, 10, 50019 Sesto Fiorentino (Florence, Italy. Abstract 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. Received 15 May 2017, Revised 15 Nov 2017, Accepted 18 Nov 2017 Keywords ! Tadelakt ! Lime, ! Marrakesh lime, ! Traditional plasters, ! Waterproof plasters. polidoro@bancadellacalce.it Phone: (+39) 051 4842426