Research Journal of Applied Sciences, Engineering and Technology 12(3): 304!311, 2016 DOI: 10.19026/rjaset.12.2337 ISSN: 2040!7459; e!ISSN: 2040!7467 © 2016, Maxwell Scientific Publication Corp. Submitted: August 8, 2015 Accepted: September 3, 2015 Published: February 05, 2016   Youssef Maaloufa, LEME, Université Mohamed V!Agdal, EST Salé, 227 Avenue Prince Héritier Sidi Mohammed Salé, Maroc This work is licensed under a Creative Commons Attribution 4.0 International License (URL: http://creativecommons.org/licenses/by/4.0/). 304                 ! " Youssef Maaloufa, Soumia Mounir, Abdelhamid Khabbazi and Jalal Kettar LEME, Université Mohamed V!Agdal, EST Salé, 227 Avenue Prince Héritier Sidi Mohammed Salé, Maroc # Insulation of building envelope has become a necessity in order to reduce the energy cost, that's why, we proceeded in this study to develop materials using clay and expanded perlite by doing several studies: the first concerns the variation of volume fraction on expanded perlite and the effect of the calcination on the thermal properties of the composite clay!expanded perlite. The second is the study of the distribution of temperature inside walls composed from the composite clay!expanded perlite. In order to achieve the results wanted, this study has been divided on several steps among them the determination of the kind of clay by means of X!ray diffraction. The results show that the clay sample is mainly made up of Illite/muscovite. Then the characterization of thermal properties of clay!expanded perlite before and after calcination. The third step, is the comparison of the experimental results with analytical models of equivalent thermal conductivity. The results show that the thermal conductivity decreases by adding expended perlite and calicination from 0.51(clay alone) to 0.258 (clay!100% expanded perlite) (W/m/K). Also, the calcination decreases the depth of heat flow diffusion by 5 cm and retards the diffusion of heat flow. $% Calcination, clay!expanded perlite, flash method, hot plate method, theoretical model, thermal conductivity, walls !&’(!’& An improved performance material such as light weight, thermal conductivity, storage ... requires the development of new composite materials. The purpose of this study is to improve the thermal properties and the lightness of the clay by combining it with expanded perlite. That's why authors try in this study to improve the insulation of construction materials by combining clay with granular expanded perlite. Also the block clay! expanded perlite was calcinated in a tunnel stove in order to see the effect of calcination on insulating the composite material clay!expanded perlite. A literature study on insulation building materials and expanded perlite was investigated so as to realize this study such as the work of Zukowski and Haese (2010) concerning the investigation of the effective thermal properties of a modern vertically perforated masonry unit filled with perlite insulation. Another for Gandage et al. (2013) determining the thermal properties of a concrete bounded with perlite. another for Abrouki (2013) concerning the characteristics of perlite in Nador city: Investigation of the basis for catalytic activity of expanded Perlite in Knoevnagel condensation. Also a lot of work have done on clay such as the work of concerning the study of the effect of cork on the thermal properties of the composite clay!cork (Mounir et al., 2014; Muñoz et al., 2013) which object is the improvement of the thermal transmittance of single!brick walls of clay bricks lightened with paper pulp. Another for Mohsen and El!Maghraby (2010) Characterizing different type of clay taken from different area in Saudia Arabia. In the present work, we aim to improve the thermal properties of the material Illite clay by combining it with granular expanded perlite and studying the effect of calcination on the thermal properties. The thermal characterization of the materials is conducted by the use of the recent asymmetrical Hot Plate (Bouchair, 2008; Jannot et al., 2010; Lin et al., 2014; Yves, 2011) and Flash methods (Degiovanni et al., 1996, 1979; Parker et al., 1961). The effect of the variation of the volume fraction of expanded perlite and calcination on the thermal properties of the brick is also studied. A comparison of thermal properties between the blocks of clay!expanded perlite before and after calcinations was conducted to identify the best energy efficient clay/expanded perlite. Perlite is a general term for a glassy, volcanic and rhyolitic rock which will expand when quickly heated to