The characteristics of the earthen materials of the Drâa valley's architecture

The Drâa valley, sited in the south-east of Morocco, is characterized by a secular heritage of earthen buildings with a great architectonic value, realized in rammed earth and earthen brick. In this region raw earth is the most important building material employed both in ordinary and monumental building. The paper reports the results of an experimental investigation carried out on samples from rammed earth walls and from earthen bricks of new production and from ancient constructions useful for restoration design of built heritage and to promote the current use of earthen materials in agreement with both tradition and modern needs. The earthen materials were characterized both from the mineralogical point of view, the grain size distribution and the consistency limits. The mechanical properties were determined both in laboratory, through uniaxial compression test and three point bending test, and in situ, through sclerometers tests. The results of the compositional, physical and mechanical analysis allowed to better know the local building technologies, making it possible to characterize the different earths employed in the buildings and to compare them with reference parameters coming from other case studies available in literature.