Abstract

Finding use for residues from felling operations has been a major focus on increasing volume recovery of harvested woody biomass. Strands and sawdust processed from left-over of Gmelina arborea residues recovered from the forest were used to produce cement bonded composites. Physical and mechanical properties of the boards were assessed showing the relationship between diverse variables such as density, wood strand and sawdust proportions. Three levels of mixing ratio and 5 levels of material blending proportion were adopted for the board formation, the mixing ratios of cement to wood material were 1:1, 2:1 and 3:1, while the wood materials were varied at 5 different levels: 100:0, 75:25, 50:50, 25:75 and 0:100 of strand to sawdust. The boards’ density recorded 800, 900 and 1000 kg/m3.  Mean water absorption ranged from 16.88±10.28 to 56.36 ±11.70%, while thickness swelling ranged from 0.21±0.20 to 5.43±0.99%. The mean values for the mechanical properties ranged from 1988.35±92.26 to 6526.90±186.06 (N/mm2) for modulus of elasticity (MOE) and 1.03±0.59 to 5.90±3.76 (N/mm2) for modulus of rupture (MOR). The result indicated that board produced at the highest mixing ratio 3:1 and at 75:25 of material blending proportion of strand to sawdust had best physical properties value and highest strength properties value. The analysis of variance carried out showed that both mixing ratio and material blending proportion had significant effect on the water absorption and modulus of elasticity while only mixing ratio had significant effect on the thickness swelling and modulus of rupture of the board. The board produced can be used as an alternative to particleboard, solid wood, asbestos, etc., for construction works at the same time increasing recovery volume.

Key words: Strand, sawdust, Gmelina arborea, physical, mechanical properties.