CONSTRUCTION FIELD MONITORING OF A COB PROTOTYPE BUILDING

Cob is an earthen building material made by soil, fibres and water used for millennia. However, cob construction disappeared out during the nineteenth century. These last years, it is experiencing a renaissance in Northwestern France and Southern England. Due to a limited technical knowledge, the investigation of engineering properties is important for modern design practice and code requirements. Moreover, to ensure building properties, it is necessary to have same quality mix along the building phases. The aim of this study is to determine material variation during the monitoring of a cob prototype building in Normandy. This study will include mix composition, water content, density, strength properties, and thermal conductivity. Samples shape used were cylindrical 110 x H220 mm and prismatic 300 x 300 x70 mm. Results indicated that there is variation in cob mix (water content, materials proportions) between three different lifts. These variations lead to different densities and, consequently, to variables compressive strengths 0.99 to 1.38 MPa and thermal conductivities from 0.610 - 0.816 W.m-1∙K-1.