Accelerated and Outdoor Ageings of Laminated Veneer Lumber and their Correlations with Strength and Stiffness

This study evaluated the effect of accelerated ageing treatment (AAT) and outdoor ageing on properties of bintangor (Callophyllum sp.) laminated veneer lumber (LVL). It established the strength correlations between AAT and outdoor ageing under tropical climate. LVLs of 1220 mm × 2440 mm were fabricated using veneers of 3.1 and 4.1 mm, producing 13- and 17-ply panels respectively. Static bending and bending shear tests were used to determine the strength of LVL after ageing. For AAT, a cyclic boil–dry (CBD) treatment was employed where specimens were submerged in boiling water for 2 hours followed by drying in an oven for 18 hours. The process was carried out for 1, 2, 5 and 10 cycles. Long-term outdoor ageing involved exposure to the tropical weather for 3 and 6 months. At each cycle and duration of exposure to the outdoor, specimens were evaluated for modulus of rupture (MOR) and modulus of elasticity (MOE) in static bending and bending shear. Statistical analysis showed that properties of bintangor LVL were significantly influenced by veneer thickness, number of CBD cycle and duration of outdoor ageing. LVL produced from thinner veneers had higher mechanical properties than that produced from thicker veneers. The former had lower property reduction after exposure to CBD treatment and outdoor ageing. The results also revealed that MOR and MOE after 2, 5 or 10 cycles of CBD treatment had high correlations with properties after 3 and 6 months of outdoor ageing.