12.1 Certain reconstituted lignocellulosic products with fibre oriented along a specific direction have been developed and are being adopted for load bearing applications. Laminated veneer lumber is one such product developed as a result of researches in plantation grown species of wood. Density of laminated veneer lumber ranges from 600 to which is manufactured in accordance with accepted standard [6-3A(12)].
12.1.1 Dimensions
Sizes of laminated veneer lumber composite shall be inclusive of margin for dressing and finishing unless manufactured to order. The margin for dressing and finishing shall not exceed 3 mm in the width and thickness and 12 mm in the length.
12.1.2 Permissible Defects
a) Jointing gaps : Not more than 3 mm wide, provided they are well staggered in their spacing and position between the successive plies.
b) Slope of grain: Not exceeding 1 in 10 in the face layers.
c) Tight knot : Three numbers up to 25 mm diameter in provided they are spaced 300 mm or more apart.
d) Warp : Not exceeding 1.5 mm per metre length.
| Sl No. | Strength Functions | Nail Laminated Vertical Laminates with Four Full Size Planks Using 8 SWG, 100 mm Long Nails | Glue Laminated | Solid (Control) Specimen | |
| Vertical Laminates Four Planks, Each 25 mm Thick | Horizontal Laminates Eight Planks, Each 30 mm Thick | ||||
| (1) | (2) | (3) | (4) | (5) | (6) |
| i) | Modulus of rupture, N/mm | 27.439 | 31.363 | 21.568 | 30.509 |
| ii) | Modulus of elasticity ( N/mm ) | 8.167 | 8.903 | 8.210 | 7.554 |
| iii) | Fibre stress at limit of proportionality, N/mm | 18.136 | 14.166 | 13.259 | 18.276 |
| iv) | Maximum horizontal shear stress, N/mm | 1.723 | 1.967 | 1.319 | 1.906 |
12.1.3 Strength Requirements
The strength requirements for laminated veneer lumber shall be as per Table 20.
| Table 20 Requirements of Laminated Veneer Lumber(Clause 12.1.3) | ||
| Sl No.(1) | Properties(2) | Requirement(3) |
| i) | Modulus of rupture, N/mm , Min | 50 |
| ii) | Modulus of elasticity, N/mm , Min | 7 500 |
| iii) | Compressive strength parallel to grain, N/mm , Min | 35 |
| iv) | Horizontal shear :a) Parallel to laminae, N/mm , Minb) Perpendicular to laminae, N/mm , Min | 68 |
| v) | Tensile strength parallel to grain, N/mm , Min | 55 |
| vi) | Screw holding power :a) Edge (N), Minb) Face (N), Min | 2 3002 700 |
| vii) | Thickness swelling in 2 h water soaking (percent), Max | 3 |