Evaluation of some mechanical and physical properties of ‘Oriented Strand Board (OSB/3)’ following cyclic accelerated aging tests

Despite the large-scale production of oriented strand board (OSB) which is produced in Europe according to EN 300: 2006 standard, and its application as roof and wall sheathing material, experimental data about its mechanical and physical properties following soaking–freezing–drying and cooling (which mimics accelerated aging) is relatively scarce. The properties of samples to be investigated according to EN standards, i.e. internal bond strength (IB), axial screw withdrawal resistance (SWR), the modulus of rupture for the major axis|| and for the minor axis⊥ (MOR||, MOR⊥), and the modulus of elasticity in bending for the major axis|| and for the minor axis⊥ (MOE||, MOE⊥), were determined by using three-point bending, together with deflection measurements by means of an optical gauge, thickness swelling (TS), and moisture content (MC). Analytical equations were used for attaining an approximation of the measured values for the aforementioned properties of OSB/3 depending upon the number of cycles involved. The values of IB and SWR (the latter in the cutting edge) dropped considerably after the first cycle, while MOR and MOE continued to decrease only a little or dropped somewhat further; TS and MC stabilised during the latter cycles. After the cyclic accelerated aging tests, the retention value of IB accounted for 61.3% of the values required in EVS-EN 300: 2006 standard: for MOR|| the corresponding value was 62.8%, and for MOR⊥, 85.0%; for MOE|| the corresponding value was 48.3%, for MOE⊥, 66.9%, and for TS, 168%. The surface and cross-section structures of the initially dry samples and the samples after the first and third soaking/oven-drying/cooling and soaking/freezing/oven-drying /cooling cycles (V313 test EVS-EN 321: 2002) were studied using X-ray technique.