3042 



Chapter 24 



Each panel was ripped parallel to the grain of the face veneers to yield three 4- 

 inch-wide and three 6-inch-wide boards 36 inches long. These 144 composite 

 boards, together with 4- and 6-inch-wide, solid-sawn, log-run southern red oak 

 and white oak boards from small pine-site trees ( 1 8 boards of each species and 

 width), and 4- and 6-inch-wide, 5-ply, 3/4-inch-thick southern pine CDX ply- 

 wood strips ripped from plywood purchased from three Louisiana sources (36 of 

 each width), were equilibrated for 30 days at 72°F and 50 percent RH. At test, 

 the composite boards contained about 6 to 7 percent moisture content, the solid 

 oak about 9 percent, and the southern pine plywood about 7 percent. All boards 

 were broken in flatwise bending with centerpoint loading over a 36-inch span 

 according to ASTM D 805 (American Society for Testing and Materials 1972). 



MOE and MOR of the 4-inch-wide boards did not differ substantially from 

 values for 6-inch-wide boards. Solid oak boards had highest MOE and MOR, 

 southern pine 5-ply CDX plywood lowest MOE and MOR, and the composite 

 boards were intermediate (table 24-30). Specific gravity of the solid-sawn oak 

 boards (0.73 based on ovendry weight and volume at test) was greater than that 

 of the composite boards (0.71) because the solid-sawn boards were taken from 

 heart-center cants, which in white oak and southern red oak are typically signifi- 

 cantly denser than the outer wood. Oak flakes, veneer, and solid boards were all 

 cut from the same trees, i.e., three 12-inch-diameter, pine-site trees of each 

 species. 



Table 24-30. — Modulus of elasticity and modulus of rupture of 3/4-inch-thick oak 

 composite boards with single 1/8- and 1/10-inch veneer faces and backs over random 

 flake cores, compared to solid-sawn oak boards and 5-ply southern pine CDX plywood, 

 all tested in bending parallel to grain of face layers (Data from Hse and Koch; see text 



footnote'^) 



Species and MOE' MOR' 



type of board 



-—Psi 



Southern red oak 



Solid-sawn 2,021,000 17,339 



Composite with 1/8-inch faces 1 ,633,000 1 1 ,955 



Composite with 1/10-inch faces 1,541,000 10,136 



White oak 



Solid-sawn 2,265,000 18,860 



Composite with 1/8-inch faces 1 ,721 ,000 1 1 ,530 



Composite with 1/10-inch faces 1 ,655,000 1 1 ,740 



Average of both oak species 



Solid-sawn 2,140,000 18,100 



Composite with 1/8-inch faces 1 ,680,000 1 1 ,700 



Composite with 1/10-inch faces 1 ,600,000 10,940 



Southern pine 5-ply CDX plywood 1 ,550,000 7,910 



'Moisture content at test of solid-sawn, composite, and plywood boards averaged 9, 6-1/2, and 7 

 percent, respectively. 



