Influence of Additive Concentration and Wood Species on Dimensional Stability of Cement-bonded Flakeboards

Abstract

The influences of additive concentration and wood species on dimensional stability of cement-bonded flakeboards were investigated. Laboratory scale flakeboards 6mm thick was made from Gmelina arborea (G), Leucaena leucocephala (L) and the mixture of the two in equal proportions. Boards were manufactured at the three levels of the raw materials and additive concentration at levels of 1.5% and 3.5% of the cement weight board. The average values obtained for Thickness Swelling (TS) following 24-hour immersion in cold water ranged from 0.90% to 2.75% for Gmelina arborea; 0.12% to 2.24% for Leucaena leucocephala; 0.39% to 1.68% for mixed materials of the wood species. For 48 hours soak, the values obtained ranged from 1.13% to 3.70%, 1.58% to 3.74% and 0.82% to 2.40% respectively. The values for Water Absorption (WA) after 24-hour water immersion ranged from 15.02% to 17.70% for Gmelina arborea; 15.71% to 19.08% for Leucaena leucocephala; 15.36% to 18.65% for mixed materials. The WA values obtained after 48 hours water immersion ranged from 17.82% to 20.01% for G; 18.77% to 20.93% for L; 18.27% to 20.36% for G + L. The dimensional stability of boards was affected by the wood species, wood density and additive concentration. Boards from Gmelina arborea, were more stable dimensionally than that made from Leucaena leucocephala, whereas the boards produced from the mixture performed better than that of Leucaena leucocephala. The TS and WA of boards decreased with increase the additive concentration. The most dimensionally stable boards were produced at the highest level of additive concentration of 3.5%, both at 24 hours and 48 hours water immersion. TS and WA were not significantly affected by species and species/additive concentration interaction, but the effect of additive concentration was significant.