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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 (France). This study investigated structural cob mix composition, water content, density, mechanical properties and thermal conductivity. Specimens shape used were cylindrical 110 x H220 mm and prismatic 300 x 300 x 70 mm. Results indicated a 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.

Between June 1989 and February 1990 the prevalence of antibodies to hepatitis C virus (anti-HCV) was studied in blood donations from 4,100 donors tested in north east France. 37 samples were found reactive for anti-HCV (prevalence of anti-HCV: 0.90%) without any significant difference in sex (males: 0.94%; females: 0.87%) and age distributions. 178 (4.34%) of the 4,100 donors were found anti-HBc positive, 5 of these donors being anti-HCV positive (13.51% of all anti-HCV positive donors). 52 donors (1.27%) had raised alanine aminotransferase (ALT) levels (greater than or equal to 2 N: 2 times the M +/- 2 SD value): 3 were found anti-HCV positive (8.11% of all anti-HCV positive donors). Association of the 2 surrogate markers is poorly sensitive since it detects only 8 (21.62%; males: 4, females: 4) of all anti-HCV positive donors. Furthermore, it appears weekly specific since it discards 230 blood samples of which 222 (96.52%) were anti-HCV negative. The 2 surrogate markers are complementary to one another and none of the anti-HCV positive donors had both anti-HBc antibodies and raised ALT. The mean ALT level is significantly higher in anti-HCV positive donors as compared to seronegative (M +/- 1 SD: 51 +/- 82 U/l versus 24 +/- 17 U/l). In anti-HCV positive donors, a marginal (r = 0.34) though statistically significant (p less than 0.05) positive correlation was found between ALT level and anti-HCV ratio.(ABSTRACT TRUNCATED AT 250 WORDS)