Evaluation of mechanical properties of OSB/3 after repetitive soaking and oven-drying cycles

The objective of this study was to evaluate some mechanical properties of OSB/3 after one to ten cycles of soaking and oven/drying (accelerated aging). The modulus of rupture (MOR), modulus of elasticity (MOE), found by 3-point bending and screw withdrawal load (SWL), were determined in dry and wet conditions in the face and back surface, and in the cutting edge. The specimens were soaked for 24 hours and dried for 48 hours in a ventilated drying box. The MOR, MOE and SWL values dropped significantly after the first cycle, continued to decrease after three cycles and stabilized in the last cycles of soaking and drying. The surface and cross-sections of the samples were also studied using the X-ray technique. This analysis explained a significant decrease in the values of the studied properties after the first soaking cycle as a result of non-restored plastic deformation of the resin matrix. The low retention values of the studied properties could raise the durability issue of the investigated commercial OSB/3 boards as they should be moisture resistant according to EN 300:2006.