EFFECTS OF BOARD DENSITY ON BENDING STRENGTH AND INTERNAL BOND OF CEMENT-BONDED FLAKEBOARDS

Abstract

AJAYI, B. & BADEJO, S. O. O. 2005. Effects of board density on bending strength and
internal bond of cement-bonded flakeboards. Single-layered cement-bonded
flakeboards were manufactured in the laboratory using two exotic tropical hardwood
species, Gmelina arborea (G) and -Leucaena leucocephala (L) and a combination of the two species at equal percentage (G + L). Boards were made to three densities of 1000,
1100 and 1200 kg m^-3 and with homogenous particle size of 50 x 2.5 mm in length
and thickness respectively. The effects of board density on modulus of rupture (MOR)
and internal bond (IB) of each species were investigated. MOR ranged from 7.7 to 9.8 N mm^-2 and 5.0 to 6.4 N mm^-2 for boards made from G. arborea and L. leucocephala respectively. MOR for boards composed of equal quantities of both species (G + L) ranged from 5.5 to 8.9 N mm-2. The IB values for G, L and G + L ranged from 0.11 to 0.16,0.06 to 0.08 and 0.08 to 0.12 N mm^-2 respectively. MOR was positively correlated with board density, unlike IB. Hence, boards from G. arborea, the lower density species, were stronger than those made from L. leucocephala or a combination of the two species. MOR of boards at different densities and species were significandy different, whereas there was no significant difference in the IB of boards at different densities.